How milk powder is made. Powdered milk production as a business: a list of equipment, a description of the manufacturing technology, the nuances of organizing a business

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Ministry of Education and Science of the Russian Federation

Federal Agency for Education

GOU VPO "Magnitogorsk State Technical University

Them. G.I. Nosov"

Department of Standardization, Certification and Food Technology

Course work

on the topic: "Technology for the production of skimmed milk powder"

Completed:

Gurevich O.V., TSP-06

Checked:

Maksimova G.K.

Magnitogorsk 2010

Introduction

1. General information

2. Technology for the production of skimmed milk powder

2.1 Requirements for raw materials for the production of skimmed milk powder

2.2 Characteristics of the technological process for the production of skimmed milk powder

3. Product calculation

4. Requirements for the quality and safety of skimmed milk powder

5. Defects of skimmed milk powder

6. Confirmation of conformity of skimmed milk powder

Conclusion

List of sources used

Introduction

An analysis of the available statistical materials shows that the dairy industry in most countries is developing steadily. From 1996 to 2001, the production of cow's milk in the world increased by 5.3%, reaching 501 million tons in 2002.

The fastest growing sector of the dairy market is the production of yoghurts and cheeses, as well as various desserts, curd products and products with biological and fruit additives.

The consumption of dairy products in 2003 was 227 kg. at the recommended consumption rate by the Institute of Nutrition of the Russian Academy of Medical Sciences - 390 kg per person per year.

Production of skimmed milk powder, whole milk substitute and whey powder for two months of 2010 increased by 5.5% to 21.89 thousand tons, dry whole milk, powdered cream and mixtures - by 41.4% to 4.068 thousand tons. Powdered milk is used for the production of confectionery and candy products, and since this area is developing very quickly, the factories of skimmed milk powder are constantly increasing production volumes and introducing new technologies. One skimmed milk powder plant can process 50-60 tons of raw materials per shift, from which approximately 2.5 tons of skimmed milk is then obtained. The by-product is oil.

The scope of skimmed milk powder is very extensive: children food, confectionery industry, ice cream, flavors, stabilizers, thickeners and other food additives, bakery industry, oil and fat industry and production of combined oils, alcohol industry, processed cheeses, cottage cheese, drinks, semi-finished products, soups, snacks, creams, sauces, complex products, dry mixes, etc. In this regard, in this course work we will consider the production of skimmed milk powder.

1 . General information

Milk canned food -- these are products made from natural milk using condensation (followed by sterilization or the addition of sugar) and drying. They have a high energy value due to the concentration of milk constituents in them. In addition, canned milk products are characterized by good transportability and significant storage stability.

Canning -- This is the processing of products in special ways in order to protect them from spoilage. Of all the known principles of conservation for the production of canned milk, two are used: abiosis and suspended animation.

Preservation by principle abiosis is based on the complete destruction of microorganisms present in the product (sterilization). Preservation according to the principle of suspended animation consists in the suppression of microbiological processes by physical means: an increase in osmotic pressure (osmoanabiosis) and drying (xeroanabiosis).

canning drying based on the removal of moisture from the product and the creation of physiological dryness, which causes an increase in the difference between the osmotic pressure in the bacterial cell and the pressure of the environment. For the normal course of processes associated with the vital activity of microorganisms, it is necessary that the mass fraction of water in the product is about 25 ... 30%. Therefore, if the amount of moisture in the product is below the minimum required for the life of microorganisms, the stability of the product during storage will increase. Mass fraction of moisture in dry milk is 3...4%; at the same time, the concentration of substances dissolved in water increases greatly and conditions are created that bring microorganisms into an anabiotic state. To prevent the development of residual microflora, the dried product must be protected from moisture absorption. The product should be stored in a hermetically sealed container at relatively low temperatures (not higher than 10°C), which inhibit the course of biochemical reactions. Dried dairy products are obtained by canning by drying.

Powdered dairy products are a powder of agglomerated milk particles of various shapes and sizes, depending on the type of product and the method of drying. The range of dry dairy products is very diverse. The main types of dry dairy products produced by the dairy industry are presented in Table 1.1.

Table 1.1 -- The main types of dry dairy products

Product name	Mass fraction fat content, %
Dry cow's milk


Powdered cream
Dry high fat cream
Powdered milk at home
Dry skimmed milk
Milk powder Smolensk
Instant whole milk powder
Dry dairy products





Dry buttermilk
Powdered milk with vegetable fat
Powdered milk with hydrogenated fat
Milk powder with malt extract

Powdered milk - powdery food product obtained by drying pre-condensed milk. Powdered milk was first obtained in 1802 in Russia by the head physician of the Nerchinsk factories, Osip Krichevsky. The first information about the production of milk powder in Europe dates back to 1885. industrial production began at the end of the 19th century.

Powdered milk is whole(SCM) or fat free(COM). These two types of milk powder differ in the percentage of substances (table 1.2). WITH ear whole milk- a dry dairy product, the mass fraction of milk solids in which is not less than 95%, the mass fraction of protein in non-fat milk solids is not less than 34% and the mass fraction of fat is not less than 20%. Skimmed milk powder- a dry dairy product, the mass fraction of milk solids in which is not less than 95%, the mass fraction of protein in skimmed milk solids is not less than 34% and the mass fraction of fat is not more than 1.5%.

Table 1.2 -- Content of substances in SCM and SOM

Instant milk powder is obtained by mixing whole and skimmed milk powder. The mixture is moistened with steam, after which it sticks together into lumps, which are then dried again.

2. Technology for the production of skimmed milk powder

2.1 Requirements for raw materials for the production of skimmed milk powder

For the manufacture of skimmed milk powder, natural cow's milk is used - raw materials not lower than the second grade according to GOST R 52054-2003 “Cow's milk - raw. Specifications” without fodder taste and smell, acidity not more than 18°T.

Natural cow's milk - raw material: Milk without extracts and additives of dairy and non-dairy components, subjected to primary processing (removal of mechanical impurities and cooling to a temperature of (4 ± 2) 0 С after milking) and intended for further processing. sour-milk skimmed milk

The basic all-Russian norm of the mass fraction of milk fat is 3.4%, the basic norm of the mass tribute of protein is 3.0%.

Milk is obtained from healthy animals on farms that are free from infectious diseases, in accordance with the Veterinary Legislation. In terms of quality, milk must comply with the requirements of GOST R 52054-2003 “Cow's milk - raw. Specifications” and Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products”. It is not allowed to use for the manufacture of the product milk that has not passed the veterinary and sanitary examination and does not have veterinary accompanying documents of the established form.

According to organoleptic parameters, milk must meet the requirements specified in Table 2.1.

In terms of physico-chemical parameters, milk must meet the requirements specified in Table 2.2.

Indicators of microbiological safety and the content of somatic cells of raw cow's milk should not exceed the permissible level established in Table 2.3 to Federal Law No. 88-FZ "Technical Regulations for Milk and Dairy Products".

Table 2.1 - Organoleptic characteristics of raw milk

Name of indicator	Norm for milk varieties

Consistency	Homogeneous liquid without sediment and flakes. Freezing not allowed
Taste and smell	Clean, free of foreign odors and flavors not characteristic of fresh natural milk
		It is allowed in the winter-spring period a slightly pronounced fodder taste and smell
	White to light cream

Table 2.2 - Physical and chemical parameters of raw milk

Table 2.3 - Indicators of microbiological safety and somatic cell content of raw cow's milk

The indicators of chemical and radiological safety of raw cow's milk should not exceed the permissible level established by Federal Law No. 88-FZ "Technical Regulations for Milk and Dairy Products".

Periodic tests are carried out according to safety indicators (the content of toxic elements, mycotoxins, antibiotics, pesticides, radionuclides; microbiological indicators) in accordance with the production control program developed by the manufacturer and approved in the prescribed manner.

2.2 Characteristics of the technological process for the production of skimmed milk powder

The technological process for the production of skimmed milk powder consists of the following technological operations: acceptance and preparation of raw materials, normalization, separation, pasteurization, thickening, homogenization, drying, cooling of the dry product, packaging and storage.

Acceptance and input control of raw milk. When accepting milk at enterprises, the quantity by weight and quality by organoleptic, physico-chemical indicators are determined in accordance with the requirements of GOST R 52054-2003 “Cow's milk - raw. Specifications” and Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products”.

When accepting milk, organoleptic indicators, temperature, density, mass fraction of fat, acidity and efficiency of heat treatment are determined in each batch, and mass fraction of protein, bacterial contamination and rennet-fermentation sample - at least 1 time per decade.

Milk purification. In the process of weighing to remove mechanical impurities, the milk is filtered, passed through a cloth, and then sent for further purification. For cleaning, filters of different systems are used, where cotton pads, gauze, synthetic materials, metal meshes, etc. are used as working elements.

At present, the enterprises of the downstream network are equipped with separators-milk cleaners, in which mechanical impurities are removed under the action of centrifugal force. Centrifugal cleaning in them is carried out due to the difference between the densities of milk plasma particles and foreign impurities. Foreign impurities, having a higher density than milk plasma, are thrown to the drum wall and settle on it in the form of mucus. Traditionally, in technological lines, centrifugal milk purification is carried out at 35-40 0 С, since under these conditions, mechanical impurities are more efficiently deposited due to an increase in the speed of particle movement. During centrifugal purification of milk, along with mechanical impurities, a significant part of microorganisms is removed, which is explained by the difference in their physical properties.

Separation- this is the separation of milk into two fractions of different density: high-fat (cream) and low-fat (skimmed milk). The separation process is carried out under the action of centrifugal force in the separator drum. The optimum separation temperature is 35-45°C. Heating the milk to this temperature ensures good skimming.

Milk pasteurization - it heat treatment milk in order to destroy vegetative forms of microflora, including pathogenic ones. The pasteurization mode should also ensure that the desired properties of the finished product are obtained, in particular, organoleptic indicators (to give taste, the desired viscosity, the density of the clot).

The effect of pasteurization, due to the degree of death of pathogenic microflora, affects the choice of modes and methods of pasteurization. Of the pathogenic microorganisms, tuberculosis bacteria are more resistant to heat treatment. Since the work on the determination of causative agents of tuberculosis is difficult, the effectiveness of pasteurization is usually determined by the death of no less resistant Escherichia coli. In the production of skimmed milk powder, it is recommended to use instant pasteurization (at a temperature of 85-87°C or 95-98°C without exposure).

Thickening. After cooling, the milk is sent for thickening, i.e. concentration of solids of milk or its mixture with components by evaporating moisture in vacuum evaporators at a pressure below atmospheric. The use of vacuum allows you to reduce the boiling point of milk and preserve its properties to the greatest extent.

To thicken milk, multi-case vacuum evaporators are used, operating on the principle of a falling film, or circulation plants.

In the continuous-flow method, continuous evaporation is carried out. The mixture, partially thickening in the first housing, successively passes through the remaining housings, where it is evaporated to the final concentration of solids, enters the product tank and is cooled.

Compared to the periodic method, the continuous-flow method reduces the time spent on processing 1 ton of milk by 1.36 times, steam consumption by 1.55 times and water by 1.46 times. In addition, the continuous-line method allows you to automate the process.

When evaporating, the main parameters of the process are the temperature, the duration of exposure and the multiplicity of concentration. Evaporation temperature, depending on the number of plant buildings and dry matter content in the mixture, varies from 45°C to 82°C. In a film vacuum evaporator, the evaporation time is from 3 minutes to 15 minutes. When thickening, the composition of canned milk can be determined in accordance with the multiplicity of concentration (or thickening). The multiplicity of concentration shows how many times the mass fractions of the dry residue and its components increase or how many times the mass of the condensed product decreases compared to the mass of the feedstock.

Homogenization - This is the process of milk processing, which consists in crushing (dispersing) fat globules by exposing milk to significant external forces.

The intensity of the homogenization process increases with increasing temperature, since in this case the fat passes completely into a liquid state and the viscosity of the product decreases. As the temperature rises, the settling of fat also decreases. At temperatures below 50°C, the settling of fat increases, which leads to a deterioration in the quality of the product. The most preferred homogenization temperature is 60-65°C. At excessively high temperatures, whey proteins in the homogenizer may precipitate.

With an increase in pressure, the mechanical effect on the product increases, the dispersion of fat increases, and the average diameter of the fat globules decreases. According to VNIKMI, at a pressure of 15 MPa, the average diameter of fat globules is 1.43 microns, and the homogenization efficiency is 74%. As the content of fat and solids in the product increases, a lower homogenization pressure should be applied, which is due to the need to reduce energy costs.

The need for homogenization of condensed milk is due to the fact that during mechanical, heat treatment and thickening, the fat fraction of milk is destabilized (liberation of free fat), which contributes to the oxidation of fat and spoilage of the product during storage. Therefore, in order to increase stability and reduce the free fat content, the milk is homogenized. Homogenization is carried out at a temperature of 50-60°C and a pressure of 10-15 MPa for a single-stage homogenizer. After homogenization, condensed milk enters the intermediate tank and then for drying.

Drying. In skimmed milk powder, the mass fraction of fat is not more than 1.5% and moisture is not more than 4-7%. Based on the composition of milk powder, it can be concluded that it is not absolutely dry, it contains the so-called non-removable moisture. As the product dries, the moisture remaining in the product is more and more firmly retained in it due to an increase in cohesive forces and an increase in resistance to water movement. Therefore, the product can only be dried to an equilibrium moisture content corresponding to the relative humidity and temperature of the drying agent.

With the spray method, drying is carried out as a result of contact of the sprayed condensed product with hot air. Condensed milk is atomized in the drying chamber using disc and nozzle atomizers. In disc atomizers, condensed milk is atomized under the action of the centrifugal force of a rotating disc, from the nozzle of which the milk exits at a speed of 150-160m/s and is broken up into tiny droplets due to air resistance. Condensed milk is supplied to nozzle sprayers under high pressure (up to 24.5 MPa).

When drying on spray dryers, condensed milk is sprayed at the top of the dryer, where hot air is supplied. Hot air, mixing with the smallest drops of milk, gives them part of the heat, under the influence of which the moisture evaporates, and the milk particles are quickly dried. The high speed of drying (evaporation) is due to the large contact surface of finely dispersed milk with hot air. With the rapid evaporation of moisture, the air is cooled to 75-95°C, so the thermal effect on the product is negligible and its solubility is high. Dried milk in the form of a powder settles to the bottom of the drying tower.

Spray dryers, depending on the movement of air and milk particles, are divided into three types: direct-flow, in which the movement of air and milk is parallel; countercurrent, in which the movement of particles of milk and air is opposite; mixed - with mixed movement of air and milk particles.

The most rational and progressive are high-performance direct-flow spray dryers, in which the degree of solubility of milk powder reaches 96-98%.

In accordance with the technical characteristics of spray dryers, the following drying modes must be observed: the temperature of the air entering the once-through type dryer should be 165-180°C, and at the outlet of the drying tower - 65-85°C. Upon exiting the drying tower, skimmed milk powder is sieved on a shaking sieve and sent for cooling.

Packaging, labeling, storage. Dry dairy products are packed in sealed consumer and transport containers. Consumer packaging includes metal cans with solid or removable cover and net weight of 250, 500 and 1000 grams; combined cans with a removable lid, having a net weight of 250, 400 and 500 grams, with an inner hermetically sealed bag of aluminum foil, paper and other materials; glued packs with cellophane liners, net weight 250 grams. Paper non-impregnated four- and five-layer bags are used as transport containers; cardboard stuffed drums; plywood-stamped barrels with polyethylene liners with a net weight of 20-30 kg.

Powdered milk in consumer containers (except for glued packs with cellophane liners) and transport containers with polyethylene liners is stored at a temperature of 0 to 10 ° C and a relative air humidity of not more than 85% for no more than 8 months from the date of production. Powdered milk in glued packs with cellophane liners and plywood-stamped barrels with cellophane and parchment liners is stored at a temperature from 0°C to 20°C and a relative air humidity of not more than 75% for no more than 3 months from the date of production.

Marking of consumer packaging, its content, place and method of application must be in accordance with GOST R51074. The marking of the shipping container in which the product is directly packaged must comply with GOST 23561. The marking of the group packaging and shipping container in which the product is packed in consumer packaging must comply with GOST 23651.

Prepared milk is cleaned on a centrifugal separator-milk cleaner, then normalized and pasteurized under the modes described above. After pasteurization, the milk enters for thickening in a three-stage vacuum evaporator, operating on the principle of a falling film. Condensed to a mass fraction of solids 43-52% milk is homogenized, sent to an intermediate container equipped with a stirrer and a heating jacket. From the intermediate container, condensed milk is pumped into the drying chamber. At the same time, it must have a temperature of at least 40 ° C.

Powdered milk is cooled with air in the pneumatic transport system. The cooled dry product from the intermediate storage bin is transported to packaging.

3 . Product calculation

The enterprise receives milk in the amount of 50 tons with a mass fraction of fat (mfl) of 3.5%.

After separation, we obtain skimmed milk with mdzh. 0.05% and cream with mdzh. 35%. Let us determine the amount of skimmed milk and cream after separation without taking into account the norms of permissible losses.

The amount of cream with a known amount of separated milk is determined by the formula (3.1):

where C l - the amount of cream;

Based on this, we obtain the following amount of cream, which will be sent for further processing to the butter shop:

The amount of skimmed milk with a known amount of separated milk is determined by the formula (3.2):

where M about - the amount of skimmed milk;

M - the amount of whole milk;

F m, F sl, F o - fat content of whole milk, cream and skim milk, respectively.

Thus, we get the following amount of skimmed milk:

We check the correctness of the calculations using the fat balance equation (formula (3.3)) of the mixture:

where F m, F sl, F o - fat content of whole milk, cream and skim milk, respectively;

M, M sl, M o - the amount of whole milk, cream and skim milk, respectively.

We present the results obtained in Table 3.1.

Table 3.1 - Summary table for the receipt and consumption of raw materials

When thickening, the composition of canned milk can be determined in accordance with the multiplicity of concentration or thickening. The multiplicity of concentration shows how many times the mass fractions of the dry residue and its components increase or how many times the mass of the condensed product decreases compared to the mass of the feedstock. The multiplicity of concentration is calculated from the following relations (3.4):

where n - multiplicity of concentration (thickening);

m cm, m etc- mass of the initial mixture and product;

WITH etc, F tsr, SOMO etc - mass fraction of solids, fat, dry fat-free milk residue in the product and, accordingly, in the initial mixture ( WITH cm, F cm, SOMO cm).

In our case, the initial mixture is skimmed milk with a solids mass fraction of 8.9%, and the product is condensed milk with a solids mass fraction of 46% (46-50% according to regulatory documents). Based on these data, the multiplicity of condensation is equal to:

Knowing the multiplicity of condensation, we can determine the mass of the condensed product using the formula (3.5):

During the production of SOM, condensed milk with a mass fraction of solids of 46% is dried to dry milk with a mass fraction of solids of 95%. Based on this, knowing the mass of condensed milk (15021.46 kg), we can determine the mass of skimmed milk powder:

9012.9kg - Xkg;

Let's present the calculations in a summary table (table 3.2).

Table 3.1 - Summary table for product calculation

Thus, out of 50 tons of milk supplied to the enterprise, with a mass fraction of fat content of 3.5%, we get 5 tons of cream with a mass fraction of fat content of 35%, which are sent to the butter workshop, and 4 tons of SMP with a mass fraction of fat content of 0.3%.

4 . Requirements for the quality and safety of skimmed milk powder

Skimmed milk powder is produced in accordance with the requirements of GOST R 52791-2007 “Canned milk. Dry milk. Specifications" according to technological instructions approved in the prescribed manner.

According to organoleptic indicators, skimmed milk powder must meet the requirements presented in Table 4.1.

Table 4.1 - Organoleptic characteristics of skimmed milk powder

Determination of organoleptic indicators of SOM is carried out in accordance with GOST 29245--91 “Canned milk. Methods for determining physical and organoleptic indicators.

According to physical and chemical indicators, skimmed milk powder must comply with the standards indicated in Table 4.2.

Table 4.2 - Physical and chemical parameters of skimmed milk powder

Name of indicator	Norm for COM
Moisture content. %, no more, for the product packed: In consumer packaging; In a shipping container.
Mass fraction of fat, %	No more than 1.5
Mass fraction of protein in dry fat-free milk residue, %. at least
Solubility index, cm 3 of raw sediment, not more, for the product packed: In consumer packaging In a shipping container
Cleanliness group, not lower
Acidity, 0 T (% lactic acid)	From 16 to 21 inclusive (from 0.144 to 0.189 inclusive)

Determination of the mass fraction of moisture SOM is carried out in accordance with GOST 29246--91 “Dry canned milk. Moisture determination methods”.

Determination of the mass fraction of fat SOM is carried out in accordance with GOST 29247--91 “Canned milk. Methods for determining fat.

Determination of the acidity of SOM is carried out in accordance with GOST 30305.3--95 “Condensed canned milk and dry milk products. Titrimetric methods for performing acidity measurements.

Determination of the solubility index SOM is carried out in accordance with GOST 30305.4--95 “Dry canned milk. Methodology for performing measurements of the solubility index”.

Determination of the content of lead, cadmium and mercury is carried out according to GOST R 51301-99 “Food products and food raw materials. Stripping voltammetric methods for determining the content of toxic elements, according to GOST 30178-96 Raw materials and food products. Atomic absorption method for the determination of toxic elements.

Table 4.3 - Permissible levels of hazardous substances in skimmed milk powder

Determination of the content of pesticides - according to GOST 23452-79 “Milk and dairy products. Methods for determination of residual quantities of organochlorine pesticides”.

According to microbiological indicators, skimmed milk powder must comply with the requirements of Federal Law No. 88-FZ "Technical Regulations for Milk and Dairy Products". These requirements are specified in Table 4.4.

The determination of QMAFAnM in SOM is carried out according to GOST 10444.15-94 “Food products. Methods for determining the number of mesophilic aerobic and facultative anaerobic microorganisms.

Table 4.4 - The content of microorganisms in skimmed milk powder

Determination of bacteria of the genus Salmonella in SOM is carried out according to GOST R 52814--2007 (ISO 6579:2002) “Food products. Method for the detection of bacteria of the genus Salmonella.

The determination of BGKP in SOM is carried out according to GOST R 52816--2007 “Food products. Methods for detection and determination of the number of bacteria of the group of Escherichia coli (coliform bacteria).

Determination of the content of Staphylococcus aureus in SOM is carried out according to GOST 30347--97 “Milk and dairy products. Methods for determining Staphylococcus aureus.

Determination of yeast and mold fungi - according to GOST 10444.12-88 “Food products. Method for the determination of yeasts and molds.

5 . vicesskimmed milk powder

Depending on the nature of the physicochemical changes in the constituent parts of milk during the manufacturing and storage process, certain defects may appear in the products.

Reduced solubility dry dairy products is observed with a strong denaturation of whey proteins during the drying process. The defect also occurs when storing a product with an increased content of free fat, which passes to the surface of the dry particles and reduces wettability. The release of free fat is facilitated by an increased moisture content in the product (more than 7%). Moisture causes crystallization of lactose with simultaneous destabilization of fat. The increased moisture content of dry dairy products, as well as storage in non-hermetic packaging, leads to a decrease in solubility due to protein denaturation and the formation of poorly soluble melanoidins. Proteins denature in the presence of free moisture in the products (bound moisture does not change the colloidal properties of the protein). In this regard, the moisture content in milk powder should not exceed 4-5%.

Darkening of canned milk occurs during the formation a large number melanoidins as a result of the reaction between the amino groups of proteins and the aldehyde group of lactose and glucose. The defect is formed as a result long-term storage dry dairy products in non-hermetic containers (in conditions of high humidity). The formation of melanoidins in milk powder is accompanied by a darkening of the product, the appearance of unpleasant specific taste and smell, and a decrease in solubility. To prevent the darkening of milk powder, it is necessary to comply with the requirements for moisture content (4-5%) and the tightness of the package. rancid taste due to the hydrolysis of fat under the action of lipase remaining after pasteurization. Occurs in spray dried dairy products.

6 . Conformity assessment of skimmed milk powder

Milk and products of its processing sold on the territory of the Russian Federation are subject to mandatory confirmation of compliance with the requirements of Federal Law No. 88-FZ “Technical Regulations for Milk and Dairy Products” (hereinafter Federal Law No. declarations on conformity (hereinafter - declaration of conformity) or mandatory certification according to the schemes established by Federal Law No. 88. Voluntary confirmation compliance with the requirements of national standards, standards of organizations, codes of practice, systems of voluntary certification and terms of contracts for milk and its processing products, processes for their production, storage, transportation, sale and disposal is carried out at the initiative of the applicant in the form of voluntary certification. The applicant has the right to choose the form of confirmation of conformity and the scheme of confirmation of conformity provided for milk and products of its processing by Federal Law No. 88.

Skimmed milk powder has a long shelf life (more than 30 days), therefore, in accordance with the requirements of Federal Law No. 88, confirmation of compliance with SOM is carried out in the form of a declaration of conformity using the 3d, 4d, 5d or 7d scheme, or in the form of mandatory certification using the 3c scheme, 4s, 5s or 6s.

Declaration of Conformity milk and products of its processing is carried out by adopting a declaration of conformity based on their own evidence and (or) on the basis of evidence obtained with the participation of the certification body and (or) accredited testing laboratory (center) (hereinafter referred to as the third party). When declaring the conformity of mass-produced milk processing products, the validity period of such a declaration of conformity is no more than five years. The following schemes for declaring conformity are used to confirm the compliance of the SOM with the requirements of Federal Law No. 88:

1) 3d- declaration of conformity of milk or products of its processing on the basis of positive results of studies (tests) of type samples of these products, obtained with the participation of a third party, and a quality system certificate at the stage of production of these products;

2) 4d- declaration of conformity of milk or products of its processing on the basis of positive results of studies (tests) of type samples of these products, obtained with the participation of a third party, and a quality system certificate at the stage of control and testing of these products;

3) 5d- declaration of conformity of a batch of milk or products of its processing on the basis of positive results of studies (tests) obtained by a representative sample of samples from a batch of these products with the participation of a third party;

4) 7d- declaration of conformity of milk or products of its processing on the basis of positive results of studies (tests) of type samples of these products, carried out on its own or with the involvement of other organizations on behalf of the applicant, and a quality system certificate at the design and production stage of these products.

The applicant accepts the declaration of conformity, registers it in accordance with the procedure established by the legislation of the Russian Federation. The applicant marks the SOM, in respect of which the declaration of conformity has been accepted, with the mark of circulation on the market.

Mandatory certification products of milk processing is carried out by the product certification body, the scope of accreditation of which extends to food products, including milk processing products, on the basis of an agreement between the applicant and the product certification body according to the schemes established by Federal Law No. 88.

The certificate of conformity for mass-produced milk processing products is issued for a period determined by the certification body depending on the state of production of these products and the stability of their quality, but not more than three years. The following mandatory certification schemes are used to confirm the compliance of the SOM with the requirements of Federal Law No. 88:

1) 3s- certification of mass-produced milk processing products based on positive test results of type samples obtained with the participation of an accredited testing laboratory (center), with subsequent control by the product certification body for certified milk processing products;

2) 4s- certification of mass-produced milk processing products based on positive test results of type samples obtained with the participation of an accredited testing laboratory (center), and analysis of the state of production of these products with subsequent control by the product certification body for certified milk processing products and, if necessary the state of their production;

3) 5s- certification of mass-produced milk processing products based on positive test results of type samples of these products, obtained with the participation of an accredited testing laboratory (center), and certification of the applicant's quality management system with subsequent control of the product certification body for certified milk processing products and body for certification of quality management systems for the certified quality management system of the applicant;

4) 6s- certification of a batch of milk processing products based on positive results of studies (tests) of a representative sample of samples of these products obtained with the participation of an accredited testing laboratory (center).

The applicant, having received a certificate of conformity for the SOM, marks it with the mark of circulation on the market. The applicant, in the production and sale of the SMP, takes the necessary measures to ensure its compliance with the requirements of Federal Law No. 88.

Conclusion

Modern industrial processing of milk is a complex set of sequentially performed interrelated chemical, physicochemical, microbiological, biochemical, biotechnological, thermophysical and other labor-intensive and specific technological processes. These processes are aimed at producing dairy products containing either all or part of the milk components. The production of canned milk is associated with the preservation of all solids in milk after removing moisture from it.

Dairy enterprises are equipped with a large number of processing equipment. Rational operation of technological equipment requires a deep knowledge of its features and design features. When using modern technological equipment, it is important to preserve to the maximum extent the nutritional and biological value of the raw materials components in the dairy products produced.

Manufacturers' desire to improve organoleptic properties, ensure the safety and profitability of products, respect the original brand name leads to a change in traditional production methods, rationalization of the composition, the development of combined dairy products with the addition of non-dairy components and the use of various food additives. Moreover, economic feasibility does not always correspond to the quality indicators, nutritional and biological value of the finished product. Thus, an increase in the timing of the sale of dairy products leads to a loss of their biological value. In this regard, the urgent task in the dairy industry is to preserve the traditional ways of producing high-quality dairy products.

List of sources used

1. Federal Law No. 88-FZ Technical regulations for milk and dairy products [Text]. - Entered 2008-06-12.

2. GOST R 52791-2007. Canned milk. Dry milk. Specifications [Text]. - Input. 2007-12-19. - M.: Gosstandart of Russia: IPK Publishing house of standards, 2007. - 8 p.

3. GOST R 52054-2003. Cow's milk is raw. Specifications [Text]. - Input. 2004-01-01. - M.: Gosstandart of Russia: IPK Publishing house of standards, 2004. - 12 p.

4. Bredikhin S.A. Technology and technology of milk processing [Text] - M.: Kolos, 2003. - 400 p. - ISBN 5-9532-0081-1.

5. Krus, G.N. Technology of milk and dairy products [Text] / Khramtsov A.G., Volokitina Z.V., Karpychev S.V. - M.: KolosS, 2006. - 455 p. - ISBN 5-9532-0166-4.

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Theoretical foundations of drying

Drying is the process of removing moisture. In the production of all types of dry dairy products, the process of removing free moisture is carried out in two stages - thickening and drying the condensed product. Thickening by evaporation is carried out to such a value of the total mass fraction of solids, at which the mass fraction of CCFC in water does not exceed 18-20% and the product does not lose fluidity.

The condensed mixtures are dried to the final moisture content, which is set depending on the forms of communication of water with the constituent parts of the dry matter of the dry matter. Final moisture content of dry dairy product, which is bound water, is not more than 15% of the mass fraction of protein in it. This is the basis for the regulation of the mass fraction of moisture in dry dairy products, upon reaching which the drying process ends.

Whole milk contains bound moisture along with free milk. Bound water is inaccessible to microorganisms, is not a solvent, does not participate in microbiological and biochemical processes, and does not freeze at 0°C. It is strongly associated with the components of milk. Its removal is accompanied by irreversible changes in the dry matter of the processed raw milk. Based on the above, bound water should be left in dry dairy products.

When drying in a stream of hot air or by contact, overheating, drying and burning of the dry powder should not be allowed.

Powdered whole milk

All technological operations for obtaining powdered milk can be divided into two groups:

processing of raw materials prior to drying;
drying and all subsequent operations.

Technological operations of the first group are common for the production of canned milk:

acceptance, quality assessment, sorting, cleaning, cooling and redundancy;
normalization of milk composition, heat treatment, thickening;
homogenization of condensed milk.

The second group of operations is:

drying, cooling of a dry product;
packing, packaging, storage.

In the production of milk powder, milk normalized for fat and dry matter is pasteurized at a temperature of at least 90°C. To thicken normalized milk, multi-case vacuum evaporators operating on the principle of a falling film or circulation plants are used. The technical parameters of thickening are maintained within the limits specified in the operating instructions for the vacuum evaporators used.

The need for homogenization of condensed milk is due to the fact that during mechanical, heat treatment and thickening, the fat fraction of milk is destabilized (liberation of free fat), which contributes to the oxidation of fat and spoilage of the product during storage. Therefore, in order to increase stability and reduce the free fat content, the milk is homogenized. Homogenization is carried out at a temperature of 50–60°C and a pressure of 10–15 MPa for a single-stage homogenizer; for a two-stage homogenizer at a pressure of 11.5–12.5 MPa at the first stage and 2.5–3.0 MPa at the second stage. After homogenization, condensed milk enters the intermediate tank and then for drying.

In dried whole milk, the mass fraction of fat is 20–25% and moisture is not more than 4–7%. Based on the composition of milk powder, it can be concluded that it is not absolutely dry, it contains the so-called non-removable moisture. As the product dries, the moisture remaining in the product is more and more firmly retained in it due to an increase in cohesive forces and an increase in resistance to water movement. Therefore, the product can only be dried to an equilibrium moisture content corresponding to the relative humidity and temperature of the drying agent.

Depending on the method of moisture removal, different ways drying: film (contact), spray (air) and sublimation.

Dryers are prepared before feeding the condensed product. To do this, the spray dryer chamber is heated for 15-20 minutes and sprayed with hot water within 5-7 minutes. Contact dryers are heated by passing hot water.

The drying mode is controlled by the main indicator - the temperature of the hot air entering the dryer and leaving it.

Film method

With film method drying is carried out in roller dryers. Condensed milk is applied by spraying or a thin layer on rotating rollers, the surface of which is heated by steam to a temperature of 105–130°C. As a result of the contact of the dried product with the hot surface of the rollers, the milk is dried in the form of a thin film. This film is removed with special knives and fed to the mill elevator for grinding. The drying process on roller dryers should not exceed 2s, since the high temperature of the heating surface causes significant changes in the dried milk. As a result of contact with a heated surface, a significant part of the fat is not protected by the shell. In this regard, and due to the low solubility of the finished product, the film method is used in the production of skimmed milk powder and whey.

Freeze Drying

When freeze drying moisture is removed from frozen products with a solids content of up to 40%. The freeze-drying process is carried out at a frozen product temperature of 25°C and a residual pressure in the sublimator of 0.0133–0.133 kPa. Freeze-dried products are easily restored, retain their taste, chemical composition and structure. Dry sour-milk products, starter cultures, ice cream mixtures are obtained by freeze-drying.

Spray drying

With the spray method drying is carried out as a result of contact of the sprayed condensed product with hot air. Condensed milk is atomized in the drying chamber using disc and nozzle atomizers. In disc atomizers, condensed milk is atomized under the action of the centrifugal force of a rotating disc, from the nozzle of which the milk exits at a speed of 150–160 m/s and is crushed into tiny droplets due to air resistance. Condensed milk is supplied to nozzle sprayers under high pressure (up to 24.5 MPa).

When drying on spray dryers, condensed milk is sprayed at the top of the dryer, where hot air is supplied. Hot air, mixing with the smallest drops of milk, gives them part of the heat, under the influence of which the moisture evaporates, and the milk particles are quickly dried. The high speed of drying (evaporation) is due to the large contact surface of finely dispersed milk with hot air. With the rapid evaporation of moisture, the air is cooled to 75–95°C, so the thermal effect on the product is insignificant and its solubility is high. Dried milk in the form of a powder settles to the bottom of the drying tower.

The most rational and progressive are high-performance direct-flow spray dryers, in which the degree of solubility of milk powder reaches 96–98%.

Prepared milk is cleaned on a centrifugal milk cleaner, then normalized and pasteurized under the modes described above. After pasteurization, the milk enters for thickening in a three-stage vacuum evaporator, operating on the principle of a falling film. Condensed to a mass fraction of solids of 43–52%, milk is homogenized, sent to an intermediate container equipped with a stirrer and a heating jacket. From the intermediate container, condensed milk is pumped into the drying chamber. At the same time, it must have a temperature of at least 40 ° C.

In accordance with the technical characteristics of spray dryers, the following drying modes must be observed:

the temperature of the air entering the once-through type dryer should be 165–180°C, and at the outlet of the drying tower - 65–85°C;
for dryers with mixed movement of air and product, the temperature of the air entering the drying tower should be 140-170°C, and at the outlet of the tower - 65-80°C.

At the exit from the drying tower, whole milk powder is sieved on a shaking sieve and sent for cooling.

instant milk

This is a dry powder, consisting of agglomerated particles, with a taste and smell characteristic of pasteurized milk; with a mass fraction of fat - not less than 25- and 15%, moisture - not more than 4%, soy-phosphatide additives - not more than 0.5%.

Features of the production of instant milk are two-stage drying, recycling of small particles involved in the formation of agglomerates, and the introduction of soy-phosphatide additives. In the production of instant milk, ordinary milk powder is obtained in the first stage of drying, which is then moistened. When the dry product is moistened, milk particles enlarge, i.e., its agglomeration, and the transition of lactose from an amorphous state to a crystalline one. At the second stage, the moistened product is dried to standard moisture. The milk particles dried in the second stage acquire a porous structure due to agglomeration. When dissolving milk with a porous structure, water penetrates into the particle and contributes to its dissolution. Rapid water penetration is also achieved by increasing wettability by adding soybean phosphatide additives.

Scheme production line the production of instant milk is similar to the production of powdered milk from acceptance to drying, but includes the following additional stages: agglomeration of powdered milk particles, return of the cyclone fraction, final drying, preparation of soybean phosphatide additives and their introduction into powdered milk. Drying of condensed milk is carried out to a mass fraction of moisture in dry milk at the outlet of the tower (3.75±2.25)%. The resulting milk powder is fed into the agglomeration chamber, where it is additionally moistened with buttermilk or skim milk to a moisture content of 7–9% by weight and agglomerated in a fluidized bed. In this case, the cyclone fraction is returned to the agglomeration chamber for re-wetting and agglomeration. Wet powder from the agglomeration chamber is sent to the first section of the instantizer, where the product is dried in a fluidized bed to a mass fraction of moisture (4.25±0.25)% at an air temperature of (105±15)°C.

A mixture of soybean phosphatide additives with ghee, prepared according to the recipe, is melted at a temperature of (65±5)°C and mixed. Then the mixture is fed into the nozzles and sent to the milk powder. After adding additives, the product is dried to standard moisture in the second section of the instantizer at an air temperature of (75±5)°C. Then the finished product is cooled to 25 °C in the third section of the instantizer.

Powdered milk can be cooled either with air in a pneumatic transport system or in a fluidized state of the product. The cooled dry product from the intermediate storage bin is transported to packaging.

Dry dairy products are packed in sealed consumer and transport containers. Consumer packaging includes metal cans with a solid or removable lid and a net weight of 250, 500 and 1000 g; combined cans with a removable lid, having a net weight of 250, 400 and 500 g, with an inner hermetically sealed bag of aluminum foil, paper and other materials; glued packs with cellophane inserts, net weight 250 g. Instant milk powder is packed in normal conditions or in a nitrogen atmosphere with preliminary evacuation. Paper non-impregnated four- and five-layer bags are used as transport containers; cardboard stuffed drums; stamped plywood drums with polyethylene liners with a net weight of 20–30 kg.

Whole milk powder in consumer containers (except for glued packs with cellophane liners) and transport containers with polyethylene liners is stored at a temperature of 0 to 10 ° C and a relative air humidity of not more than 85% for no more than 8 months from the date of production. Powdered milk in glued packs with cellophane liners and plywood-stamped barrels with cellophane and parchment liners is stored at a temperature of 0 to 20 ° C and a relative air humidity of not more than 75% for no more than 3 months from the date of production. Powdered instant milk with 15 and 25% fat content is stored at a temperature of 1 to 10°C, relative humidity not more than 85% and not more than 6 months from the date of production.

To expand the range of dry dairy products, products with reduced and increased fat content, dry sour-milk products and ice cream mixes are produced.

Dry dairy products produced from normalized condensed milk fermented with pure cultures lactic acid bacteria, by drying in spray dryers. The production of dry fermented milk products is similar to the production of dried whole milk with the introduction of an additional operation - fermentation of condensed milk.

Dry mixes for ice cream obtained by spray drying pasteurized mixtures made from whole, skimmed milk, cream, sugar, stabilizer and fillers, or by mixing a dry milk base with powdered sugar. Features of the production of dry mixes for ice cream are to carry out additional operations for the preparation of components and the composition of the mixture.

Spray drying proved to be the most suitable technology for removing residual water from the stripped off product, as it allows turning the milk concentrate into a powder, while retaining the valuable properties of milk.

The principle of operation of all spray dryers is to turn the concentrate into fine droplets, which are fed into a fast stream of hot air. Due to the very large droplet surface (1 liter of concentrate is sprayed on 1.5 × 10 10 drops with a diameter of 50 μm with a total surface of 120 m 2 ) evaporation of water occurs almost instantly, and
droplets turn into powder particles.

Single stage drying

Single-stage drying is a spray drying process in which the product is dried to the final residual moisture in the spray dryer chamber, see figure 1. The theory of droplet formation and evaporation in the first drying period is the same for both single-stage and two-stage drying and is described here.

The initial speed of droplets falling off the rotary atomizer is approximately 150 m/s. The main drying process takes place while the drop is decelerated by air friction. Drops with a diameter of 100 µm have a stagnation path of 1 m, while drops with a diameter of 10 µm have only a few centimeters. The main decrease in the temperature of the drying air, caused by the evaporation of water from the concentrate, occurs during this period.

Giant heat and mass transfer occurs between the particles and the surrounding airfor a very a short time, therefore, the quality of the product can suffer greatly if the factors that contribute to the deterioration of the product are left unattended.

When water is removed from the droplets, a significant decrease in the mass, volume and diameter of the particle occurs. At ideal conditions drying mass drops from a rotary atomizer
is reduced by approximately 50%, volume by 40% and diameter by 75%. (See Figure 2).

However, the ideal technique for creating droplets and drying has not yet been developed. Some air is always included in the concentrate as it is pumped out of the evaporator and especially when the concentrate is fed into the feed tank due to splashing.

But even when spraying the concentrate with a rotary atomizer, a lot of air is included in the product, since the atomizer disc acts as a fan and sucks in air. The incorporation of air into the concentrate can be counteracted by using specially designed discs. On a disk with curved blades (the so-called disk of high bulk density), see Figure 3, the air is partially separated from the concentrate under the action of the same centrifugal force, and in a disk washed with steam, see Figure 4, the problem is partially solved by the fact that instead of a liquid-air contact, there is a liquid-vapor contact here. It is believed that when spraying with nozzles, air is not included in the concentrate or is included to a very small extent. However, it turned out that some air is included in the concentrate at an early stage of spraying outside and inside the spray cone due to the friction of the liquid on the air even before the formation of droplets. The higher the nozzle output (kg/h), the more air enters the concentrate.

The ability of the concentrate to incorporate air (ie foaming capacity) depends on its composition, temperature and dry matter content. It turned out that the concentrate with a low solids content has a significant foaming capacity, which increases with temperature. A concentrate with a high solids content foams significantly less, which is especially pronounced with increasing temperature, see Figure 5. In general, whole milk concentrate foams less than skim milk concentrate.

Thus, the air content in the droplets (in the form of microscopic bubbles) largely determines the decrease in the volume of the drop during drying. Another, even more important factor is the ambient temperature. As already noted, an intensive exchange of heat and water vapor occurs between the drying air and the droplet.

Therefore, a temperature and concentration gradient is created around the particle, so that the whole process becomes complicated and not entirely clear. Drops of pure water (water activity 100%) evaporate upon contact with high-temperature air, maintaining the temperature of the wet bulb until the very end of evaporation. On the other hand, products containing dry matter, at the limit of drying (i.e. when the water activity approaches zero), are heated towards the end of drying to ambient temperature, which, in the case of a spray dryer, means the outlet air temperature. (See Figure 6).

Therefore, the concentration gradient exists not only from the center to the surface, but also between the points of the surface, as a result, different parts of the surface have different temperatures. The overall gradient is greater the larger the particle diameter, as this means a smaller relative surface area. Therefore, fine particles dry out more
evenly.

During drying, the solids content naturally increases due to the removal of water, and both viscosity and surface tension increase. This means that the diffusion coefficient, i.e. the time and zone of diffusion transfer of water and steam becomes smaller, and due to the slowing down of the evaporation rate, overheating occurs. In extreme cases, the so-called surface hardening occurs, i.e. the formation of a hard crust on the surface through which water and steam or absorbed air diffuse
So slow. In the case of surface hardening, the residual moisture content of the particle is 10-30%, at this stage proteins, especially casein, are very sensitive to heat and easily denature, resulting in a hardly soluble powder. In addition, amorphous lactose becomes hard and almost impermeable to water vapor, so that the temperature of the particle increases even more when the evaporation rate, i.e. diffusion coefficient approaches zero.

As water vapor and air bubbles remain inside the particles, they overheat, and if the ambient air temperature is high enough, the vapor and air expand. The pressure in the particle increases and it inflates into a ball with a smooth surface, see Figure 7. Such a particle contains many vacuoles, see Figure 8. If the ambient temperature is high enough, the particle may even explode, but if this does not happen, the particle still has a very thin crust, about 1 micron, and will not withstand machining in a cyclone or conveying system so that it leaves the dryer with exhaust air. (See Figure 9).

If there are few air bubbles in the particle, then the expansion, even when overheated, will not be too strong. However, overheating as a result of surface hardening deteriorates the quality of casein, which reduces the solubility of the powder.

If the ambient temperature, i.e. If the temperature at the outlet of the dryer is kept low, the temperature of the particle will also be low.

The outlet temperature is determined by many factors, the main ones being:

moisture content of finished powder
temperature and humidity of the drying air
solids content in concentrate
spraying
concentrate viscosity

Moisture content of finished powder

The first and most important factor is the moisture content of the finished powder. The lower the residual humidity must be, the lower the required outlet air relative humidity, which means a higher air and particle temperature.

Temperature and humidity of drying air

The moisture content of the powder is directly related to the moisture content of the air leaving, and increasing the air supply to the chamber will result in a slightly greater increase in the output air flow, since more moisture will be present in the air due to increased evaporation. The moisture content of the drying air also plays an important role, and if it is high, the outlet air temperature must be increased to compensate for the added moisture.

Dry matter content in concentrate

Increasing the solids content will require a higher outlet temperature as evaporation is slower (average diffusion coefficient is smaller) and requires a larger temperature difference (driving force) between the particle and the surrounding air.

spraying

Improving atomization and creating a more finely dispersed aerosol allows you to reduce the outlet temperature, because. the relative surface of the particles increases. Because of this, evaporation proceeds more easily and the driving force can be reduced.

Concentrate viscosity

Atomization depends on viscosity. Viscosity increases with protein content, crystalline lactose and total solids content. Heating the concentrate (be aware of aging thickening) and increasing the atomizer disk speed or nozzle pressure will solve this problem.

The overall drying efficiency is expressed by the following approximate formula:

where: T i - inlet air temperature; T o - outlet air temperature; T a - ambient air temperature

Obviously, in order to increase the efficiency of spray drying, it is necessary either to increase the ambient air temperature, i.e. preheat the exhaust air, for example, with condensate from an evaporator, either increase the air inlet temperature or lower the outlet temperature.

Dependence ζ temperature is a good indicator of the efficiency of the dryer, since the outlet temperature is determined by the residual moisture content of the product, which must meet a certain standard. A high outlet temperature means that the drying air is not being optimally used, for example due to poor atomization, poor air distribution, high viscosity, etc.

For a normal spray dryer processing skimmed milk (T i = 200°C, T o = 95°C), z ≈ 0.56.

The drying technology discussed so far referred to a plant with a pneumatic conveying and cooling system, in which the product discharged from the bottom of the chamber is dried to the required moisture content. At this stage, the powder is warm and consists of agglomerated particles, very loosely bound into large loose agglomerates, formed during primary agglomeration in the spray cone, where particles of different diameters have different speeds and therefore collide. However, when passing through the pneumatic transport system, the agglomerates are subjected to mechanical stress and crumble into separate particles. This type of powder, (see Figure 10), can be characterized as follows:

individual particles
high bulk density
dusting if it is skimmed milk powder
not instant

Two stage drying

The particle temperature is determined by the ambient air temperature (outlet temperature). Because bound moisture is difficult to remove by conventional drying, the outlet temperature must be high enough to provide the driving force (Δ t, i.e. temperature difference between particle and air) capable of removing residual moisture. Very often this degrades the quality of the particles, as discussed above.

Therefore, it is not surprising that a completely different drying technology was developed, designed to evaporate the last 2-10% of moisture from such particles.

Since evaporation at this stage is very slow due to the low diffusion coefficient, the equipment for post-drying must be such that the powder remains in it for a long time. Such drying can be carried out in a pneumatic conveying system using hot conveying air to increase the driving force of the process.

However, since the rate in the transport channel must be≈ 20 m/s, effective drying requires a channel of considerable length. Another system is the so-called “hot chamber” with a tangential entry to increase exposure time. Upon completion of drying, the powder is separated in a cyclone and enters another pneumatic conveying system with cold or dehumidified air, where the powder is cooled. After separation in the cyclone, the powder is ready for bagging.

Another finishing system is the VIBRO-FLUIDIZER, i.e. a large horizontal chamber divided by a perforated plate welded to the body into upper and lower sections. (Figure 11). For drying and subsequent cooling, warm and cold air is supplied to the distribution chambers of the apparatus and is evenly distributed over the working area by a special perforated plate, BUBBLE PLATE.

This provides the following benefits:

The air is directed down to the surface of the plate, so the particles move along the plate, which has rare but large holes and therefore can work for a long time without cleaning. In addition, it is very well freed from the powder.
The unique manufacturing method prevents the formation of cracks. Therefore, BUBBLE PLATE meets strict sanitary requirements and approved by the USDA.

The size and shape of the holes and the air flow are determined by the air velocity required to fluidize the powder, which in turn is determined by the properties of the powder, such as moisture content and thermoplasticity.

The temperature is determined by the required evaporation. The size of the holes is chosen so that the air speed ensures the fluidization of the powder on the plate. The air speed should not be too high so that the agglomerates are not destroyed by abrasion. However, it is not possible (and sometimes not desirable) to avoid entrainment of some (especially fine) particles from the fluidized bed with air. Therefore, the air must pass through a cyclone or bag filter where the particles are separated and returned to the process.

This new equipment allows you to carefully evaporate the last percent of moisture from the powder. But this means that the spray dryer can be operated in a different way than described above, in which the powder leaving the chamber has the moisture content of the finished product.

The advantages of two-stage drying can be summarized as follows:

higher output per kg of drying air
increased economy
best product quality:

good solubility
high bulk density
low free fat
low content of absorbed air

Less powder emissions

The fluidized bed can be either a piston-type vibrofluidized bed (VibroFluidizer) or a fixed backmix fluidized bed.

Two-stage drying in the Vibro-Fluidizer(piston flow)

In the Vibro-Fluidizer, the entire fluidized bed is vibrated. The perforations in the plate are made in such a way that the drying air is directed along with the powder flow. Forso that the perforated plate does not vibrate with its own frequency, it is mounted on special supports. (See Figure 12).

Figure 12 - Spray dryer with Vibro-Fluidizer for two-stage drying

The spray dryer operates at a lower outlet temperature, resulting in higher moisture content and lower particle temperature. The wet powder is discharged by gravity from the drying chamber into the Vibro-Fluidizer.

There is, however, a limit to the decrease in temperature, since due to the increased humidity, the powder becomes sticky even at a lower temperature and forms lumps and deposits in the chamber.

Typically, the use of the Vibro-Fluidizer allows you to reduce the outlet temperature by 10-15 °C. This results in a much gentler drying, especially at the critical stage of the process (30 to 10% moisture content), particle drying (see Figure 13) is not interrupted by surface hardening, so that drying conditions are close to optimal. The lower particle temperature is partly due to the lower ambient temperature, but also due to the higher moisture content, so that the particle temperature is close to the wet bulb temperature. This, of course, has a positive effect on the solubility of the finished powder.

A decrease in outlet temperature means a higher efficiency of the drying chamber due to an increase inΔ t. Very often, drying is carried out at a higher temperature and with a higher solids content in the raw material, which further increases the efficiency of the dryer. This, of course, also increases the outlet temperature, but the increased moisture content reduces the temperature of the particles, so that overheating and surface hardening of the particles do not occur.

Experience shows that the drying temperature can reach 250°C or even 275°C when drying skimmed milk, which raises the drying efficiency to 0.75.

Particles reaching the bottom of the chamber have a higher moisture content and more low temperature than traditional drying. From the bottom of the chamber, the powder enters directly into the drying section of the Vibro-Fluidizer and is immediately liquefied. Any curing or handling will cause the warm, wet thermoplastic particles to stick together and form lumps that are difficult to break. This would reduce the drying efficiency of the Vibro-Fluidizer and some of the finished powder would have too much moisture, i.e. the quality of the product would suffer.

Only powder from the drying chamber enters the Vibro-Fluidizer by gravity. Fines from the main cyclone and from the cyclone serving the Vibro-Fluidizer (or from the washable bag filter) are fed into the Vibro-Fluidizer by a transport system.

Since this fraction is smaller in size than the dryer powder, the moisture content of the particles is lower and they do not require the same degree of secondary drying. Very often they are quite dry, however, they are usually fed into the last third of the drying section of the Vibro-Fluidizer to ensure the required moisture content of the product.

The powder discharge point from the cyclone cannot always be placed directly above the Vibro-Fluidizer to allow the powder to flow into the gravity dryer section. Therefore, a pneumatic conveying system is often used to move the powder. The pneumatic conveying system makes it easy to deliver the powder to any part of the plant, since the conveying line is usually a 3" or 4" milk pipe. The system consists of a low flow, high pressure blower and blow off valve, and collects and transports the powder, see Figure 14. The amount of air is small relative to the amount of powder transported (only 1/5).

A small portion of this powder is again blown away by the air from the Vibro-Fluidizer and then transported from the cyclone back to the Vibro-Fluidizer. Therefore, if special devices are not provided, when the dryer is stopped, a certain time is required to stop such circulation.

For example, a distribution valve can be installed in the transfer line, which will direct the powder to the very last part of the Vibro-Fluidizer, from where it will be discharged in a few minutes.

At the final stage, the powder is screened and packed into bags. Since the powder may contain primary agglomerates, it is recommended to direct it to the bunker by means of another forced pneumatic conveying system in order to increase the bulk density.

It is well known that during the evaporation of water from milk, the energy consumption per kg of evaporated water increases as the residual moisture approaches zero. (Figure 15).

The drying efficiency depends on the air inlet and outlet temperature.

If the steam consumption in the evaporator is 0.10-0.20 kg per kg of evaporated water, then in a traditional single-stage spray dryer it is 2.0-2.5 kg per kg of evaporated water, i.e. 20 times higher than in the evaporator. Therefore, attempts have always been made to increase the solids content of the evaporated product. This means that the evaporator will remove a larger proportion of the water and the energy consumption will be reduced.

Of course, this will slightly increase the energy consumption per kg of evaporated water in the spray dryer, but the overall energy consumption will decrease.

The above steam consumption per kg of evaporated water is an average, since the steam consumption at the beginning of the process is much lower than at the end of drying. Calculations show that to obtain a powder with a moisture content of 3.5%, 1595 kcal / kg of powder is required, and to obtain a powder with a moisture content of 6% - only 1250 kcal / kg of powder. In other words, the last evaporation step requires approximately 23 kg of steam per kg of water evaporated.

The table illustrates these calculations. The first column reflects the operating conditions in a traditional plant, where the powder from the drying chamber is sent to the cyclones by a pneumatic conveying and cooling system. The next column reflects the operating conditions in a two-stage dryer in which drying from 6 to 3.5% moisture is carried out in a Vibro-Fluidizer. The third column represents two-stage drying at high inlet temperature.

From the indicators marked with *), we find: 1595 - 1250 \u003d 345 kcal / kg of powder

Evaporation per kg of powder is: 0.025 kg (6% - 3.5% + 2.5%)

This means that the energy consumption per kg of evaporated water is: 345/0.025 = 13.800 kcal/kg, which corresponds to 23 kg of heating steam per kg of evaporated water.

In the Vibro-Fluidizer, the average steam consumption is 4 kg per kg of evaporated water, which naturally depends on the temperature and the drying air flow. Even if the steam consumption of the Vibro-Fluidizer is twice as high as that of a spray dryer, the energy consumption to evaporate the same amount of water is still much lower (since the product processing time is 8-10 minutes, not 0-25 seconds, as in spray dryer). And at the same time, the productivity of such an installation is greater, the product quality is higher, powder emissions are lower, and the functionality is wider.

Two-Stage Drying with Fixed Fluid Bed (Back Mix)

To improve the drying efficiency, the outlet air temperature To in two-stage drying is reduced to the level at which the powder with a moisture content of 5-7% becomes sticky and begins to settle on the walls of the chamber.

However, the creation of a fluidized bed in the conical part of the chamber provides a further improvement in the process. Air for secondary drying is fed into the chamber under the perforated plate, through which it is distributed over the powder layer. This type of dryer can operate in a mode in which the primary particles dry up to a moisture content of 8-12%, which corresponds to an outlet air temperature of 65-70 °C. This utilization of the drying air makes it possible to significantly reduce the size of the installation with the same dryer capacity.

Powdered milk has always been considered difficult to fluidize. However, a special patented plate design, see Figure 17, ensures that air and powder move in the same direction as the primary drying air. This plate provided right choice bed height and fluidization start speed allows you to create a static fluidized bed for any milk-derived product.

The static fluidized bed (SFB) apparatus is available in three configurations:

with an annular fluidized bed (Compact dryers)
with circulating fluidized bed (MSD dryers)
with a combination of such layers (IFD dryers)

Annular fluidized bed (Compact dryers)

An annular backmix fluidized bed is located at the bottom of the cone of a traditional drying chamber around a central exhaust air pipe. Thus, there are no parts in the conical part of the chamber that interfere with the air flow, and this, together with the jets emerging from the fluidized bed, prevents the formation of deposits on the walls of the cone, even when processing sticky powders with a high moisture content. The cylindrical part of the chamber is protected from deposits by a wall blowing system: a small amount of air is tangentially supplied at high speed through specially designed nozzles in the same direction in which the primary drying air swirls.

Due to the rotation of the air-dust mixture and the cyclone effect that occurs in the chamber, only a small amount of powder is carried away by the exhaust air. Therefore, the proportion of powder entering the cyclone or washable bag filter, as well as the emission of powder to the atmosphere, is reduced for this type of dryer.

The powder is continuously discharged from the fluidized bed by flowing through the adjustable height baffle, thus maintaining a certain level of the fluidized bed.

Due to the low outlet air temperature, the drying efficiency is significantly increased compared to traditional two-stage drying, see table.

After leaving the drying chamber, the powder can be cooled in a pneumatic conveying system, see Figure 20. The resulting powder consists of individual particles and has the same or better bulk density than that obtained by two-stage drying.

P Fat-containing products should be cooled in a vibrating fluidized bed, in which the powder is agglomerated at the same time. In this case, the fines fraction is returned from the cyclone to the atomizer for agglomeration. (See Figure 21).

Circulating fluidized bed (MSD dryers)

To further increase drying efficiency without creating problems with build-up of deposits, a completely new spray dryer concept has been developed - the MultiStage Dryer (multi-stage dryer), MSD.

In this apparatus, drying is carried out in three stages, each of which is adapted to the humidity of the product characteristic of it. In the pre-drying stage, the concentrate is atomized by direct-flow nozzles located in the hot air channel.

The air is fed into the dryer vertically at high speed through an air diffuser that ensures optimum mixing of the droplets with the drying air. As already noted, on this evaporation occurs instantaneously, while the droplets move vertically downward through a specially designed drying chamber. The moisture content of the particles is reduced to 6-15%, depending on the type of product. At such high humidity, the powder has high thermoplasticity and stickiness. Air entering at high speed creates a Venturi effect, i.e. sucks in ambient air and entrains small particles into a humid cloud near the atomizer. This leads to “spontaneous secondary agglomeration”. The air entering from below has sufficient velocity to fluidize the layer of settled particles, and its temperature provides the second stage of drying. The air leaving this backmix fluidized bed, together with the exhaust air from the first drying stage, exits the chamber from above and is fed into the primary cyclone. From this cyclone, the powder is returned to the backmix fluidized bed and air is fed into the secondary cyclone for final cleaning.

When the moisture of the powder is reduced to a certain level, it is discharged through a rotary lock into the Vibro-Fluidizer for final drying and subsequent cooling.

The drying and cooling air from the Vibro-Fluidizer passes through a cyclone where the powder is separated from it. This fine powder is returned to the nebulizer, to the chamber cone (static fluidized bed) or to the Vibro-Fluidizer. In modern dryers, cyclones are being replaced by bag filters with CIP.

A coarse powder is formed in the plant, which is due to “spontaneous secondary agglomeration” in the atomizer cloud, where dry fine particles constantly rising from below adhere to semi-dry particles, forming agglomerates. The agglomeration process continues when the pulverized particles come into contact with the fluidized bed particles. (See Figure 22).

Such a plant can be operated at very high inlet air temperatures (220-275°C) and extremely short contact times, still achieving good powder solubility. This installation is very compact, which reduces the requirements for the size of the room. This, plus the lower operating cost due to the higher inlet temperature (10-15% less compared to traditional two-stage drying), makes this solution very attractive, especially for agglomerated products.

Figure 22 - Multistage Spray Dryer (MSD)

Spray Drying with Inline Filters and Fluid Beds (IFD)

The patented built-in filter dryer design, (Figure 23), utilizes proven spray drying systems such as:

Feed system with heating, filtration and concentrate homogenization equipped with high pressure pumps. The equipment is the same as in traditional spray dryers.
Spraying is done either by jet nozzles or an atomizer. Jet nozzles are mainly used for fatty or high protein products, while rotary atomizers are used for any products, especially those containing crystals.
The drying air is filtered, heated and distributed by a device that creates a rotating or vertical flow.
The drying chamber is designed to provide maximum hygiene and minimize heat loss, for example through the use of removable
hollow panels.
The built-in fluidized bed is a combination of a back mixing bed for drying and a piston type bed for cooling. The fluidized bed apparatus is fully welded and has no cavities. There is an air gap between the backmix bed and the surrounding piston type bed to prevent heat transfer. It uses the new patented Niro BUBBLE PLATE plates.

The air removal system, despite its revolutionary novelty, is based on the same principles as the Niro SANICIP bag filter. Fines are collected on filters built into the drying chamber. The filter sleeves are supported by stainless steel meshes attached to the ceiling around the circumference of the drying chamber. These filter elements are backflushed just like the SANICIP™ filter.

The sleeves are blown one or four at a time with a jet of compressed air, which is fed into the sleeve through a nozzle. This ensures regular and frequent removal of the powder that falls into the fluidized bed.

It uses the same filter media as the SANICIP™ bag filter and provides the same air flow per unit area of media.

Backflush nozzles perform two functions. During operation, the nozzle is used for blowing, and during cleaning in place, liquid is supplied through it, washing the sleeves from the inside out, to the dirty surface. Clean water is injected through the blowback nozzle, sprayed with compressed air on the inner surface of the hose and squeezed out. This patented scheme is very important, since it is very difficult or impossible to clean the filter media by flushing from the outside.

To clean the underside of the ceiling of the chamber around the sleeves, nozzles of a special design are used, also playing a dual role. During drying, air is supplied through the nozzle, which prevents powder deposits on the ceiling, and when washing, it is used as a conventional CIP nozzle. The clean air chamber is cleaned with a standard CIP nozzle.

Advantages of the IFD™ installation

Product

Higher yield of first-class powder. In traditional cyclone dryers with bag filters, a second grade product is collected from the filters, the proportion of which is approximately 1%.
The product is not subjected to mechanical stress in channels, cyclones and bag filters, and the need for fines return from external separators is eliminated, since the distribution of flows inside the dryer ensures optimal primary and secondary agglomeration.
Product quality is improved because the IFD™ can operate at a lower outlet air temperature than a traditional spray dryer. This means that a higher drying capacity per kg of air can be achieved.

Safety

The protection system is simpler, since the entire drying process takes place in one apparatus.
Protection requires fewer components.
Maintenance cost is lower

Design

Easier installation
Smaller building dimensions
A simpler support structure

Environment protection

Less possibility of powder leakage into the working area
Easier cleaning as the area of equipment contact with the product is reduced.
Less effluent with CIP
Less powder emission, up to 10-20 mg/nm 3 .
Energy savings up to 15%
Less noise level due to lower pressure drop in the exhaust system

Today, your own food production business is becoming increasingly important, as this industry allows you to get good profits. Unfortunately, at present, many entrepreneurs do not pay attention to the production of milk powder at all.

But this is sad and stupid! In most regions of our country, there are no local producers left at all. Meanwhile, the needs Food Industry in this raw material are large, and sometimes it has to be imported from abroad.

Where is it used

Oddly enough, but milk powder is used much more often than ordinary people remember it. For example, it is used for the production of expensive varieties of natural cosmetics, for the manufacture of reconstituted milk and some fermented milk products. This is especially true for the regions of the Far North, where cows (for obvious reasons) cannot be kept.

Of course, it finds wide application in the confectionery industry, in canning and in the manufacture of animal feed. In a word, the production of milk powder is justified, if only because the sales market is huge, and its saturation is negligible.

This is especially true for those regions where dairy farming is poorly developed for some reason.

Raw materials used

The advantage of the freeze-dried milk production business is that it does not require large investments. As a raw material, it is permissible to use the cheapest milk with low fat content and the maximum content of somatic cells. The requirements of GOSTs and the Federal Laws equated to them (which do not yet exist) are quite soft.

Development prospects

Establishing the production of milk powder, you can count on its further development. You have every chance to establish a full-fledged plant producing all types of dairy products. Given the cost of it in recent years, you are unlikely to complain about low profits.

If you are not afraid of strict SES requirements and constant inspections, we recommend that you pay attention to the production of powdered milk formulas for baby food.

In addition, the same equipment can be used to produce egg powder, bases for soups and broths, and perform extraction.

Thus, you get a multifunctional complex that can bring huge profits. By the way, how much is dry milk?

Even in international markets, the demand for powdered milk is huge: for example, up to 4 thousand dollars can be earned per ton of this product in the USA and Canada, in Australia it can be sold at about the same price, and Europe buys it for 3-3.5 thousand. Please note - these are only low-fat varieties!

If we talk about products of standard fat content (about 25%), then a batch of such milk will go at 5 thousand per ton. In our country, a ton of products with the same fat content will cost about seven thousand rubles. Despite this, even in our country the production of powdered milk is quite a profitable business, the profitability of which is 30-40%.

Workshop requirements

The premises in which these food products will be produced must necessarily meet sanitary requirements. The presence of a plumbing system, sewerage and heating, as well as electrical wiring designed for 380 volts, is required.

It is absolutely necessary to equip the workshop with systemic forced ventilation, til the floor and walls with ceramic tiles. You can use plastic or other materials that can be washed and disinfected well for this purpose. Warehouses are subject to the same requirements, with the exception of optional heating in this case.

Necessary equipment

For the production of freeze-dried milk, only one installation is required. This is a special drying chamber, the design of which includes several nodes at once, a pump, the sublimation chamber itself, which runs on gas or electricity, a hopper for finished products. Powdered milk is fed to a special sieving unit, after which it goes to a packaging machine. You will also need recuperators, conveyors and fans, fat content meters, etc.

Direct production technology

The technology of powdered milk production itself includes several stages at once: acceptance of the feedstock and its purification from mechanical impurities, normalization of fat content, pasteurization and cooling. After that, in the sublimation chamber, it is first thickened, then brought to a homogeneous consistency, after which it is finally dried.

Let's consider all stages of the process in more detail.

Detailed description of production

First, the milk is heated to a temperature of 35-40 degrees Celsius. After that, it goes to the purifier, where it is driven through a filter system that removes fine fluff, wool and other debris from it that has passed through the filters on the farm.

Often, powdered milk producers in Russia are faced with a high content of somatic cells. This is due to the fact that cows with mastitis are not so rarely milked into the general stream. So in our case, there are no extra filters!

Milk is heated so that products with different organoleptic characteristics are mixed as evenly as possible. Immediately after this, it is sent to the normalizer, where it is separated into a product with the required fat content and cream.

After that comes the turn of pasteurization, the conditions of which can vary greatly depending on its type: if the milk is heated to 65 degrees for half an hour, then we are talking about a long variety; when it heats up to 95 degrees within a minute - about a short one, and at 98 degrees and a couple of seconds of heating - about instantaneous.

This process serves to destroy harmful microflora. After that, the milk is cooled, filtered again, and then enters the sublimation chamber, where it is evaporated until 40% of the dry matter remains in the mixture.

Then the resulting composition is homogenized, that is, brought to a homogeneous consistency. And only after that the production of skimmed milk powder goes to the final stage, when it is subjected to final drying. In the future, the finished product is packaged in branded packaging.

Equipment and its cost

Today on the market there are many offers for the sale of the equipment you need. Moreover, for approximately 55-60 million rubles, you can become the owner of a monoblock complex, on which it is easy to produce not only milk powder, but also the entire line of dairy products, even cheeses.

A separate sublimation plant will cost around 10 million rubles. The price depends on the capacity, manufacturer, and other factors. It will be necessary to purchase additional cooling and heating units, pasteurization machines and fat content analyzers, filtration systems and tanks.

What to buy: a ready-made plant or each component separately?

If you see which equipment for the production of milk powder you need to purchase separately, then you will probably decide that buying a plant (monoblock) is more justified. Basically, that's the way it is. First, it will be much easier to set up. Secondly, having the opportunity to produce such a wide range of products, you will find your niche in the market in any case.

Simply put, high-quality and fresh dairy products will be happy to be sold by retail chains. Another thing is that finding a suitable site for such a large-scale production can be difficult.

Alternative approaches

Despite the extremely high profitability of the sale of powdered milk in regions with poor agricultural development, an entrepreneur may just find himself in a situation where there is simply no raw material for production.

In this case, the only optimal solution may be to organize your own small dairy farm for at least 500 head of cattle. Of course, all this makes it ten times more expensive to set up your business, but in the future you can receive excellent dividends.

In addition, we once again draw your attention to the fact that, whenever possible, you should not focus only on milk powder: the more varieties of this product you produce, the more protected you are from market risks.

In this case, the business will become much more sustainable. In a word, summing up all of the above, I would like to recommend building a plant for the production of powdered milk in those regions where there are no problems with raw materials. In this case, it will be necessary to establish good logistics to deliver products to areas where there is a shortage.

Product characteristics of raw materials and semi-finished products. Powdered dairy products are a type of canned milk. The latter can be divided into three groups: condensed with sugar, sterilized and dry. Powdered dairy products are a powder of agglomerated milk particles of various shapes and sizes, depending on the type of product and the method of drying.

Dry dairy products have a high nutritional and energy value. Whole milk powder contains 25.6% protein, 25% fat, 39.4% lactose, and skimmed milk powder 37.9% protein and 50.3% lactose. These foods are also high in vitamins and minerals. The energy value 100 g of dry dairy products is 1500 ... 2500 kcal. The moisture content of dry dairy products does not exceed 4%, which ensures a significant duration of their preservation in hermetic packaging. One of the main physical and chemical indicators of dry canned food is solubility, the value of which can range from 80 to 99.5%, depending on the drying method.

The range of dry dairy products is very diverse. The main type of dry dairy products produced by the domestic dairy industry is cow's milk powder with a fat mass fraction of 15, 20, 25% and skimmed milk, cream powder, as well as dried sour-milk products and buttermilk.

Raw materials for the production of dry dairy products are milk of at least 2nd grade and an acidity of not more than 20 °T, cream with a mass fraction of fat of not more than 40% and an acidity of not more than 26 °T, skimmed milk and buttermilk with an acidity of not more than 20 °T.

Features of production and consumption of finished products. The volumes of production of natural milk and other dairy products during the year are uneven, especially in the autumn-winter period, when the supply of fresh milk is reduced. One of the ways to ensure a rhythmic dairy production is the use of powdered milk produced in special dairy production. In addition, powdered milk makes it possible to economically store and transport very large quantities dry matter to remote regions and for export.

Features of the production of dry dairy products in comparison with the production of drinking milk provide for additional heat treatment of milk: evaporation and drying.

Evaporation designed to remove water and increase the concentration of non-volatile solids (up to 50%), resulting in the formation of condensed milk.

Such milk or milk mixture is a colloidal system. Salts and carbohydrates are contained in condensed milk in the state of a molecular solution, proteins are in a colloidal state, and fat is in the form of an emulsion.

Milk is usually evaporated under vacuum when the boiling point of the product is lowered. This method improves the technological performance of the equipment and reduces the negative impact of high temperature on the quality of milk powder. Depending on the number of evaporation steps, the boiling point is maintained from 70...80 °C to 43...48 °C.

The ratio of the final concentration of any component of milk to its initial concentration is commonly called the degree of thickening. The value of the latter depends on the design of the evaporator equipment. The degree of milk thickening in a circulating vacuum evaporator is 43…48%, and in a film one – 52…54%, with a thickening duration of 50 and 3…4 minutes, respectively.

Drying is intended for obtaining a dairy product with a solids concentration of at least 96%. Milk is usually dried in contact or spray dryers. In contact dryers, milk dries in direct contact with the hot surface of the drums (rollers). Depending on the design of these dryers, milk can be dried at atmospheric pressure at a temperature of 110...130 °C and in vacuum at a temperature of 60...70 °C. As a drying agent, water vapor is used, supplied to the inside of the drums and heating their working surfaces.

In spray dryers, milk is dispersed using rotating discs or nozzles to fine droplets. An increase in the specific surface area of the product during drying makes it possible to intensify the release of moisture. Due to the small size of milk droplets (40...50 microns), the moisture exchange surface reaches 150...250 m 2 per cubic meter of the drying chamber. Therefore, the drying time does not exceed 4…6 s.

The shelf life of dried whole milk in sealed packaging at a temperature of 1 ... 10 ° C is no more than 10 months.

Stages of the technological process. The production of milk powder consists of the following stages and main operations:

- receiving milk, sorting by quality and measuring the amount of milk received;

– purification from mechanical impurities and cooling of raw milk;

– heating and separation of milk;

– formation of a normalized milk mixture: normalization, purification and pasteurization;

– thickening of normalized milk;

– homogenization of condensed milk;

– drying of condensed milk;

– cooling of milk powder;

- packaging of the finished product in consumer and transport containers.

Characteristics of equipment complexes. The milk powder production line starts with a complex of equipment for preparing raw milk for processing, including self-priming pumps, flow meters, filters, cooling units and milk storage tanks.

The next in the line is a complex of equipment for the formation of a normalized milk mixture, containing pumps, heat exchangers, separators, dispensers of components, tanks and filters for a normalized milk mixture.

Further, the line contains a complex of equipment for milk thickening, which has multi-case vacuum apparatuses or circulating vacuum evaporators, homogenizers, filters and tanks for cooling condensed milk.

The leader is a complex of equipment for milk drying, including dryers, vibrating screens and devices for cooling milk powder.

The line ends with a set of equipment for packing powdered milk into consumer and transport containers.

The machine-hardware diagram of the milk powder production line is shown in Figure 2.19.

The device and principle of operation of the line. After quality checking, accounting, cleaning and cooling raw milk loaded into receiving tanks 1 . Raw milk is pumped for processing by a centrifugal pump 2 through plate heater 3 , milk separators 4 into separator-normalizer 5 .

Normalization of milk is carried out by adding cream, skimmed milk or buttermilk to it. In a normalized milk formula, the ratio of fat and dry milk fat-free residue should be the same as in the finished product. Standardized milk from the tank 6 pumped to the pasteurization-cooling plant 7 . Milk is pasteurized at a temperature of 95 ° C without exposure, filtered and loaded into supply tanks 8 .

Rice. 2.19. Machine-hardware diagram of the milk powder production line

The milk is thickened in a film-type vacuum evaporator. The installation includes three heating chambers 10 with vapor separators 11 , tubular heaters 13 and 14 , product pipeline with pumps 12 , heating steam supply system 9 , capacitor 17 with steam jet pumps 18 and pumps for pumping condensed milk 15 and condensate 16 .

For evaporation, milk is pumped from above into the pipes of the heating chamber 10 and flows down, forming a thin film on the inner surface of the tubes. Heating steam enters the annular space, heats the product to the boiling point. The vapor-liquid mixture of the product from the lower section of the heating chamber enters the separator-steam separator 11 . In it, the flow is divided into secondary steam, which enters the heating of the next chamber, and the evaporated product, which is pumped by a pump into the pipes of the next chamber. From the last (third) chamber, condensed milk is pumped by a pump 15 into the intermediate tank 19 , and the secondary steam enters the condenser 17 , turns into a liquid and is pumped 16 to the condensate collection system.

In order to prevent fat sludge, condensed milk is homogenized. This operation is carried out in a two-stage homogenizer 20 valve type. The product is heated to 55...60 °C and homogenized at a working pressure of 11.5...12.5 MPa in the first stage and 2.5...3.0 MPa in the second stage. Homogenized condensed milk is filtered and accumulated in a stirred bath 21 .

Condensed milk is fed for drying by a gear pump 22 passing through the spray disc 24 for dispersion. Atomized product in the working volume of the drying tower 25 dried in an atmosphere of hot air blown through a heater 23 . The temperature of the air entering the drying tower is 165…180 °С, and the temperature of the exhaust air is 65…85 °С.

Powdered milk is unloaded from tower 25 using cyclones 26 and 27 , sifted on a sieve with a mesh size of 22 mm and cooled to 15 ... 20 ° C in a pneumatic transport system 28 . Chilled milk powder is packed into consumer containers using a machine 29 . Packets of milk are placed in boxes.

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How milk powder is made. Powdered milk production as a business: a list of equipment, a description of the manufacturing technology, the nuances of organizing a business

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How milk powder is made. Powdered milk production as a business: a list of equipment, a description of the manufacturing technology, the nuances of organizing a business

Send your good work in the knowledge base is simple. Use the form below

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