RU2201093C2 - Method of producing dry dairy product - Google Patents

Abstract

FIELD: dairy industry; applicable for preparation of dry dairy product. SUBSTANCE: method involves pasteurization and concentration of fat-free milk and whey, and preparation of mixture. In concentrated whey, before mixture preparation, conducted are isomerization of lactose in lactulose by introduction of alkali solution up to pH 10.5-11.5 units at temperature 75-85 C, and thermostatic control. Then concentrated fat-free milk is introduced in concentrated whey in terms of ratio of mass part of dry substances in concentrated whey and concentrated fat-free milk from 30:70 to 70:30, respectively, in mixture mass. After it, mixture is dried. The invention provides enrichment the product with bifidogenic agent - lactulose, biologically full-value proteins and free amino acids of fat-free milk. EFFECT: increased food and biological value. 1 tbl, 3 ex

Description

 The invention relates to the dairy industry and can be used to obtain a dry milk product based on whey (raw cheese, curd and casein) and skim milk.

 A method has been developed for the production of Belact dry milk product, which includes the operations of accepting raw materials, pasteurizing and cooling skim milk and whey, deoxidizing whey, making a mixture, thickening and drying (Belact dry milk product. TU 49 1180-85, 1985, 30 from.).

The disadvantage of this method is the fact that when serum is deoxidized to neutral pH values, the effect of isomerization of lactose into lactulose is not achieved, since this reaction proceeds at a temperature of at least 60 ^° C and a pH of at least 10.0-10.5 units. Therefore, the product in question does not have bifidogenic properties.

 The closest in technical execution to the proposed method for the production of dry milk product is a method for the production of whey powder, which includes collecting, storing, heating, separating, pasteurizing, cooling, isomerizing lactose into lactulose, thickening and drying the condensed whey (Method for the production of dry whey. RU 2098977 C1, A 23 C 21/10, 12/20/1997 A.G. Khramtsov, A.D. Lodygin, S.A. Ryabtseva, I.A. Evdokimov, L.N. Zhurba). This product is characterized by a high content of lactulose - a carbohydrate with bifidogenic properties. However, when using dry concentrates based on milk raw materials in food and feed formulations, in some cases, they are required to increase the protein content. In this regard, there is a real need to enrich whey-based dry concentrates in protein composition, for example, by the introduction of skim milk.

 The technical result of the invention is the enrichment of a dry milk product with bifidogenic factor lactulose, biologically complete proteins and free amino acids of skim milk, which increases its nutritional and biological value.

To do this, in the proposed method for the production of dry milk product, involving the acceptance of raw materials (skim milk and whey), pasteurization of skim milk and whey, thickening the components, making a mixture, drying the mixture, isomerization of lactose into lactulose in condensed whey by adding alkali to it to achieve a pH of 10.5 to 11.5 units at a temperature of 75-85 ^o C and temperature control for 25-35 minutes

 The method is as follows.

The acceptance of skim milk and whey, pasteurization and cooling of skim milk and whey, thickening the components of the mixture. In condensed milk whey, lactose isomerization into lactulose is carried out. To do this, in a whey condensed to 20-30% dry matter (when drying the mixture on a roller dryer) or 30-40% dry matter (when drying the mixture on spray dryers), calcium hydroxide solution is added until a pH of 10.5-11 is reached, 5 units at a serum temperature of 75-85 ^o C and thermostat for 25-35 minutes. In this case, part of the lactose (20-30% of the mass fraction of lactose in the condensed serum) isomerized into lactulose. The selected pH values are due to the need to achieve a concentration of OH ^- ions in serum, which ensures the catalytic transformation of aldose (lactose) to ketose (lactulose). A further increase in pH values is impractical because during the preparation of the mixture, the protein phase of skim milk can be destabilized and it becomes necessary to introduce an additional operation to neutralize isomerized whey.

The indicated temperature range is justified by the fact that at temperatures below 75 ^o C the reaction of lactose isomerization into lactulose is inhibited or completely blocked, while an increase in temperature above 85 ^o C leads to irreversible changes in the components of whey, and the deterioration of its organoleptic characteristics. The indicated range of duration of temperature control corresponds to the maximum accumulation of lactulose in serum; its increase is undesirable due to the formation of by-products of the reaction of alkaline hydrolysis of lactulose and melanoidin formation, which leads to a decrease in the yield of the final product.

 The mixture is then compiled, and the ratio of the mass fractions of solids in the condensed milk whey and the condensed skim milk can vary from 30:70 to 70:30, respectively. The resulting mixture is dried on spray or roller dryers; mass fraction of moisture in the finished product should not exceed 5%. The result is a dry milk product enriched with bifidus factor lactulose and biologically complete proteins and free amino acids of skim milk.

 The composition of the obtained dry milk product in comparison with dry whey produced by the method described above (RU 2098977 C1, A 23 C 21/10, 12/20/1997) is shown in the table. The mass fraction of solids in the test samples was determined by drying to constant weight; mass fraction of protein - by the Kjeldahl method; mass fraction of lactulose - by gas-liquid chromatography.

Example 1. Raw materials (skim milk and whey) are taken by weight and quality. Serum must be pre-fat-free and cleaned of casein dust on a self-discharging cream separator. The components of the mixture are pasteurized on a plate pasteurization-cooling unit: skim milk - at 76 ^o With a delay of 15 s; whey - at 74 ^o With an exposure of 15 s.

Skim milk is concentrated on a vacuum film evaporator at 70 ^o C to a mass fraction of solids of 30%, cooled to a temperature of not more than 10 ^o C and sent to a storage tank. Milk whey is condensed under a similar regime to a mass fraction of solids of 30% and sent to a capacitive apparatus equipped with a jacket and stirrer to carry out isomerization of lactose into lactulose. For this purpose, a saturated solution of calcium hydroxide (milk of lime) is introduced into the whey at the indicated temperature until a serum pH of 10.5 units is reached. (pH is determined potentiometrically or using universal indicator paper) and incubated for 35 minutes. Then, condensed skim milk is added to the tank apparatus based on the ratio of the mass fraction of dry solids of whey and skim milk in the mass of the mixture 70 and 30%, respectively.

The resulting mixture is dried on a roller dryer at a steam pressure of 0.05 MPa, the temperature of the mixture before being fed to the dryer should be at least 50 ^o C. The mass fraction of solids in the product is 95%, including lactulose 10.6%; protein - 26.3%.

Example 2. Acceptance and pasteurization of the components of the mixture (whey and skim milk) is carried out according to example 1. Skim milk is concentrated in a vacuum circulation evaporator at 65-70 ^o C to a mass fraction of solids of 35%, cooled to a temperature of not more than 10 ^o C and sent for storage in a capacitive apparatus with a jacket and stirrer. Milk whey is concentrated at a similar temperature to a mass fraction of solids of 40% 30 minutes before the thickening process is completed, the temperature is raised to 80 ^° C and a solution of calcium hydroxide is added in an amount necessary to achieve a serum pH of 11.0 units, keeping at these temperature and pH for 30 minutes Thus, the isomerization of lactose into lactulose is carried out directly in a vacuum evaporator. Next, make up the mixture by introducing condensed whey into a container with skim milk based on the ratio of the mass fraction of dry solids of whey and skim milk in the mass of the mixture 50:50, respectively. The resulting mixture is dried on a spray dryer in the following mode: the air temperature at the inlet to the drying tower is 165 ^o C, the air temperature at the outlet of the tower is 75 ^o C. The mass fraction of solids in the product is 95.2%, including lactulose 8.2 %; protein 21.9%.

Example 3. Acceptance and pasteurization of the components is carried out as in example 1. Skim milk is concentrated in example 2 to a mass fraction of solids of 30%, cooled and sent for storage. The thickening of serum and isomerization of lactose into lactulose is carried out according to example 2; isomerization process parameters: serum pH 11.5 units; temperature 85 ^o C, duration 25 minutes The composition of the mixture is carried out according to example 2 from the calculation of the ratio of the mass fraction of solids of whey and skim milk in the mass of the mixture 30:70, respectively. The mixture is dried on a spray dryer according to example 2. The mass fraction of solids in the product is 95%, including lactulose 5.5%, protein 18.1%. Thus, dry milk product is enriched with lactulose and milk proteins, which increases its nutritional and biological value.

Claims (1)

A method for the production of a dry milk product, comprising the acceptance of skim milk and whey, pasteurization of skim milk and whey, thickening the components and making the mixture, drying the mixture, characterized in that lactose isomerization into lactulose by injection of an alkali solution in the condensed milk whey to achieve a pH of 10.5-11.5 at 75-85 ^o C and thermostating for 25-35 min, after which condensed skim milk is added to the condensed milk whey from the calculation and the ratio of the mass fraction of solids in condensed milk whey and condensed skim milk in the mass of the mixture from 30: 70 to 70: 30, respectively.

Images