For production of skim milk powder there are used skim milk, buttermilk obtained at production of sweet  butter.

Norms for skim milk powder.

 

Organoleptic characteristics.
Parameter Characteristics
Taste and smell Peculiar topasteurizedskimmilkwithoutforeignflavors. Itispermissibletohaveflavoradsmellofboiledmilk
Consistency Fine powder or powder consisted of separate or agglomerated particles of milk powder. It is permissible to have insignificant number of lumps fall into pieces under slight mechanical effort
Color White, white with light cream shade

 

Physical and chemical parameters.
Parameter Norm for SMP

Moisture content, %, not more than,

For packaged product:

- consumption package

- transport package

 

 

4,0

5,0

Fat content, % < 1,5
Lactose content, % 47,0 - 54,0
Protein content in skim solids, %, not less than 34,0
Cleanliness, group, not lower I
Acidity, 0Т, (% lactic acid) 14 - 21 (0,126 - 0,189)

Solubility, cm3 raw sludge, not more than, for packaged product:

- consumption package

- transport package

 

0,2

0,2

 

Scheme of milk processing:

                                                         Milk

                                                   /                      \

                                     Skim milk        Cream— Butter

                                                                           /

                                                                   Buttermilk

                                                   \              /                                                                                               

                                                     Formula                                   

                                                             ↓

                                                          SMP      

 

The principle operations of the skim milk powder production:

Acceptance and evaluation of the quality of raw product. Milk is tested for organoleptic (color, smell, taste), physical and chemical (density, acidity, fatness, purity) and microbiological parameters. After sorting by quality milk is filtered and its mass is determined.

Cooling and storage of milk. Accepted milk is pre-cooled to the temperature of (4 ± 2) °С depending on the conditions and duration of storage and is stored till the beginning of processing keeping the temperature. For better preservation of raw milk and improvement of the quality of the finished product it is possible to carry out sanation (partial removal of microorganisms) of raw milk by its bactofugation or microfiltration and / or preparatory heat treatment (thermization, low-temperature pasteurization). Preparatory heat treatment of raw milk can be combined with the separation process.

Purification of accepted milk. After temporary storage milk is sent for purification from mechanical impurities. From the storage tanks milk enters the recovery section of pasteurizing and cooling plant where it is heated to the temperature (50 ± 2) 0С (depending on the used plants) and then goes to milk clarifying separator from which is fed to the cream separator for defating.

Production and storage of skim milk. Skim milk is obtained by separating preheated to (50 ± 2) °С milk. Cream with the set fat content obtained in the separation of whole milk is heated and transported to another site for further processing. If the conditions of production require the storage of skim milk, then after receiving it is cooled to (4 ± 2) °С and pasteurized just before condensation.

Pasteurization of skim milk. Skim milk is heated in the plate pasteurizing and cooling plant under the following modes:

  • At the temperature (87 ± 2) °С or at the temperature (94 ± 2) °С with the following cooling.

 

After temporary storage chilled pasteurized skim milk goes to condensation.

Condensation of skim milk. To save energy carriers and reduce load on the vacuum evaporator it is useful to carry out the condensation process in two stages.

Stage 1 – condensing on the reverse osmosis plant to the concentration of solids in the retentate 18%. The filtration process is carried out on special reverse osmosis membranes that can withstand high pH and high temperature of cleaning.

Stage 2 – final condensing in the vacuum evaporator of film or circulation type in continuous mode to the concentration of (46 ± 2)% solids.

Condensed milk is filtered and fed into the receiving tank of the drying plant equipped with agitator and jacket. To store condensed milk at the temperature of condensation for more than one hour is not recommended. In case the forced storage condensed milk must be cooled to (6 ± 2) °С.

Ultrafiltration of skim milk. In order to standardize milk that is sent for drying and to obtain the finished product of the normalized composition the ultrafiltration plant is used. During membrane filtration of skim milk there is obtained ultrofiltrat (protein concentrate) and permeate (protein free milk).

Standardization of formula by protein content. Standardization of formula by protein content is carried out by mixing calculated amount of components (retentate and permeate) in the tanks or in flow using the metering device.

Drying of condensed milk. Drying of skim milk concentrate in the spray drying plant of one pass type to the moisture content in the finished product approximately 4-5%. Drying modes:

  • air temperature at the inlet of the drying chamber - from 170 to 190 °С;
  • air temperature at the outlet of the drying chamber - from 75 to 90 °С;

 

During operation there are monitored temperature and mass fraction of solids in the condensed milk supplied for drying, the moisture content in the final product, acidity in reconstituted milk, the parameters of the drying process.

Cooling of powder. After leaving the drying chamber milk powder is screened, then cooled in the plant with vibrofluidized bed of the temperature no higher than 250C. Thecooledproductissenttopackaging.

© PSC "Kalinovskiy machine building plant" 1934-2019