Justification of the choice of measuring process
Technological process of production of kefir
Kefir is developed reservoir and thermostately in the ways.
Technological process consists of the following operations: acceptance and preparation of raw materials, normalization, homogenization, pasteurization and cooling, a zakvashivaniye, souring in special capacities, coolings of a clot, maturing of a clot, fasovaniye.
Raw materials.
Kefir is developed in the reservoir way from the whole genuine normalized milk not below the second grade, acidity by no more than 19 0 T, with a density not less than 1,0278 kg/m3, with various mass fraction of fat therefore initial milk is normalized to the required mass fraction of fat. At normalization of whole milk on fat there can be two options: it is more fat in whole milk, than it is required in production, and it is less fat in whole milk, than it is required. In the first option fat is partially selected by separation or add fat-free to initial milk. In the second option for increase in fat content of initial milk add to him cream. One of the simplest ways of normalization on fat – normalization by mixing in the capacity of the calculated amounts of the normalized milk and the normalizing component (cream or skim milk) at careful hashing of mix.
Thermal treatment and homogenization.
Pasteurization of milk is made for the purpose of destruction of vegetative forms of microflora, including pathogenic. The most widespread way in production of fermented milk products – short-term pasteurization at a temperature of 85-87 0 C with endurance within 5-10 min. or at 90-92 0 C with endurance of 2-3 min. with the subsequent cooling up to the zakvashivaniye temperature. The mode of pasteurization has to provide the set properties of a ready-made product, in particular organoleptic indicators (taste, the necessary viscosity and density of a clot). High temperatures of pasteurization cause a denaturation of serumal proteins, at the same time hydration properties of casein increase. It promotes formation of more dense clot which well holds moisture that interferes with office of serum at storage.
Homogenization is a smashing (dispergating) of fatty balls by impact on milk of considerable external efforts. In processing the sizes of fatty balls and speed of emerging decrease. There is a redistribution of obolochechny substance of a fatty ball, the fatty emulsion is stabilized, and the homogenized milk doesn't settle. Now apply the two-level homogenization excluding adhesion of parts of fatty balls at the exit from a valvate crack of the homogenizing head. Homogenization is carried out at a temperature of 60-65 0 C and pressure of 15-17,5 MPas (125-175 atm). After pasteurization and homogenization mix is cooled up to the zakvashivaniye temperature.
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Fermentationand souring of milk.
By production of kefir usually apply the ferment made on kefiric fungi. Their main representatives are lactic sticks, lactic streptococci, including aromatobrazuyushchy and milk yeast like Torula. Casual microflora of grains consists of sporous sticks, acetic bacteria, dairy pleseny, filmy yeast, bacteria of the Colii group of the ave.
For preparation of kefiric ferment dry kefiric grains keep in warm water (25-30 0 C) within a day, changing her during this time 2-3 times. After that water is merged, and the bulked-up grains fill in with the warm milk taken in tenfold quantity in relation to the volume of fungi.
For development of kefir with characteristic taste and strong consistence it is necessary to use the production ferment matured after souring at a temperature of 10-12 0 C within 12-24 hour. Ferment which mass usually is 5% of mass of the fermented mix is brought in the mix cooled up to the zakvashivaniye temperature. Mix is skvashivat at a temperature of 23-25 0 C before formation of a milk protein clot acidity of 80-100 0 T (рН 4,5-4,65). During souring there is a reproduction of microflora of ferment, the acidity increases, coagulates casein and the clot is formed. After the end of souring the product is immediately cooled.
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