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Definition of peroxidase on reaction with yodistokaliyevy starch
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It is applied to detection of pasteurization of milk at a temperature above 80o (to sustain 20s), at which enzyme of peroxydase inaktivizirutsya. The method is based on hydrogen peroxide decomposition by enzyme the peroxidase containing in milk. The active oxygen which is released at decomposition of a prekisa of hydrogen oxidizes iodide potassium releasing the iodine giving connection of blue color with starch.
Technology of definition: To 5 ml of the studied milk add 5 drops of solution of yodistokaliyevy starch and 5 drops of 0,5% solution of peroxide of hydrogen to a test tube. After addition of each reactant add test tube contents.
Then determine availability of peroxidase by coloring change. Emergence of dark blue coloring indicates existence in peroxidase enzyme milk, therefore raw milk. Lack of coloring within 1 minute after addition of reactants - an absence sign in peroxidase milk, milk is pasteurized at a temperature above 80o by Page.
It should be noted what even in boiled milk after addition of reactants can appear after a while pale голоубое coloring owing to gradual decomposition of H2O2 without enzyme influence.
Definition of phosphatase on reaction with 4-aminoantipiriny
(an arbitration method)
The essence of a method is that the enzyme which is contained in milk phosphatase is capable to hydrolyze disodium salt of fenilfosforny acid. The emitted free phenol in the presence of an oxidizer with 4-aminoantipiriny gives pink coloring.
Technology of definition: To 3 ml to milk add 2 ml of working solution to a test tube, mix contents and put on a water bath at a temperature 40-45os for 30 minutes.
The test tube is taken out from a bath, add 5 ml of a precipitator of system zinc-copper, carefully mix contents of a test tube and again put in a bath at a temperature 40-45os for 10 minutes. Having taken out a test tube from a water bath visually compare her contents to check experiment. The similar experiment made with boiled milk is control.
If coloring of contents of a test tube colourless, then milk is pasteurized at a temperature not lower than 63 ° C. Coloring of contents of a test tube from pink to dark red indicates that raw milk, or milk was exposed to heating at a temperature below 63 ° C, or has been mixed with crude.
Report on performance of a task
By results of researches to draw the corresponding conclusions.
Control questions:
1. Milk pasteurization purpose.
2. The factors influencing efficiency of pasteurization.
3. Justification of the choice of the modes of thermal treatment by production of various dairy products.
4. What mode of thermal treatment define breakdown on phosphatase?
5. How pasteurization influences structure and properties of dairy raw materials?
Laboratory work №7
Studying of technological features of production of drinks on the basis of whey
Work purpose: acquaintance with technological processes of production of drinks of skim milk, buttermilk and different types of serum. To estimate quality of the received products.
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Task:
1. To make technological schemes of production of drinks;
2. To make recalculation of compoundings of drinks;
3. To develop drinks according to technological schemes;
4. To carry out assessment of quality of ready drinks on the basis of physical and chemical and organoleptic indicators;
5. To issue results of work and to draw the corresponding conclusions.
Short theoretical data
Euphorbia serum turns out as a by-product by production of proteinaceous products. In many countries serum is used in production of ice cream, bakery and confectionery, products of baby food, medicines. Considerable volumes of whey go for production of the condensed and dry concentrates, and also forages for animals.
Drinks belong to one of the biggest assortment groups of products of whey. Nutrition value and biological properties of whey allow to use her directly as drink or, after preliminary processing, as raw materials for preparation of various drinks.
In drinks from whey there is no casein and milk fat, in separate types of drinks also serumal proteins can be removed. At the same time separate groups of drinks can be enriched with proteins of milk due to addition of buttermilk, skim milk or dairy proteinaceous concentrates, and also products from vegetable raw materials (soy, etc.).
The mineral and microelement composition of whey approaches structure of mineral water, but considerably surpasses her in nutritional value. Therefore drinks from serum not only promote a satisfying of thirst and maintenance of water-salt balance, but also are nutritious.
Technological process of production of drinks of the native not fermented serum is carried out in this sequence:
- acceptance, assessment of quality and preparation of raw materials;
- pasteurization and cooling of serum;
- introduction of nutritional supplements and sugar syrup;
- pasteurization and cooling of mix;
- fragrance introduction (if necessary);
- hashing and cooling of mix;
- pouring, packing, marking, dookhlazhdeniye of a ready-made product.
In the clarified serum specific serumal smack is weakened, and from it receive the transparent refreshing drinks.
Biological processing of whey leads to change of its structure, accumulation of organic acids, water-soluble vitamins, lactates, flavoring and aromatic substances, allows is directed to change a ratio of "belok:uglevoda" in the desirable party and to improve taste of the developed drinks.
Technological process of production of the fermented drinks of serum is carried out in the following sequence:
- acceptance, assessment of quality and preparation of raw materials;
- pasteurization and cooling of serum;
- introduction of nutritional supplements and sugar syrup;
- pasteurization and cooling of mix up to the zakvashivaniye temperature;
- zakvashivaniye and souring;
- fragrance introduction (if necessary);
- hashing and cooling of skvashenny mix;
- pouring, packing, marking, dookhlazhdeniye of a ready-made product.
On organoleptic indicators drinks from whey have to conform to the requirements provided in table 7.1
Organoleptic indicators of drinks from whey Table 7.1
| Indicator | Characteristic |
| Consistence and appearance | Uniform (transparent or opaque), slightly viscous liquid, is allowed an insignificant deposit of protein. With existence of small fruit particles (for drinks with fruit fillers) |
| Taste and smell | Sweet-sour, refreshing, with the expressed taste and a smell of the brought fruit filler or/and fragrance |
| Color | Uniform, uniform on all weight, caused in color of the brought filler. |
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Drinks from whey have to meet for physical and chemical indicators the requirements provided in table 7.2.
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