SU1105506A1 - Method of obtaining lactose - Google Patents

Abstract

METHOD OF PREPARING LACTOSE, including thickening the molasses of refined milk sugar at 60-65 ° C to a dry matter content of 50-58%, crystallization by cooling the condensed solution to 10-15 sec. and obtaining crystals of uniform size, the crystallization is carried out in two steps, the first of which is condensed molasses is cooled in natural conditions to 30-40 s and maintained for 2-6 hours, and cooling to 1015c is carried out in the second step during 6-10 hours.

Description

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The invention relates to dairy industry, in particular to methods for producing lactose from molasses of refined milk sugar.

A method of producing lactose is known, comprising thickening the molasses of refined milk sugar at a temperature of 60-65 ° C to a solids content of 50-58%, crystallization by cooling the condensed solution to a temperature of 10-15 seconds, and centrifuging m,

The disadvantages of this method are low lactose yield and non-uniform crystal size.

The purpose of the invention is to increase the yield of lactose and to obtain crystals of uniform size.

The goal is achieved in that according to the method, including the condensation of molasses of refined milk sugar at 60-65 ° C to a solids content of 50-58%, crystallization by cooling the condensed solution to 10-15 ° and centrifuging, the crystallization is carried out in two steps, in the first of which, the condensed molasses is cooled in natural conditions to 30-40 ° C and held for 2-6 hours, and cooling to 10-15 seconds is carried out in the second stage for 6-10 hours.

The method is carried out as follows.

The molasses of refined milk sugar is concentrated at a temperature of 6065 ° C to a dry matter content of 5058%. The resulting syrup is subjected to crystallization by cooling to a final temperature of 10-15 seconds. Moreover, the crystallization process is carried out in two stages: in the first of which, the condensed molasses is cooled in natural conditions to a temperature of 30-40 ° C and held for 2-6 hours, and cooling to 10-15 ° C is carried out in the second stage for 6 -10 h. The resulting crystallized is subjected to centrifugation.

In the process of producing lactose for crystallization, the condensing temperature and the solids content of the syrup are important. The preferred temperature range for molasses is 60-65 0. The thickening of molasses at temperatures above 65 ° C leads to caramelization and lactose hydrolysis. To maintain the temperature

condensations not higher use vacuum evaporators. A decrease in temperature below 60 ° C leads to a sharp increase in the duration of condensation on these devices, which ultimately leads to acidification of the condensable product.

The concentration of lactose in the syrup determines the diffusion rate of the molecules, the size, the shape of the crystals and the degree of crystallization. A prerequisite for crystallisation is the lactose c. solution. However, it is impractical to thicken the syrup to obtain lactose crystals, as is customary in beet sugar production, since the efficiency of crystallization of lactose (due to lower solubility) is 10 times lower than the efficiency of crystallization of sucrose. As the solids grow in the syrup, more crystallization centers form, but the size of the crystals decreases, which is undesirable in the production of lactose. Reducing the solids content can eliminate the formation and growth of crystals. Therefore, there should be an optimum solids content. The degree of percolation of lactose syrups is a decisive indicator of the crystallization process and is 1.7-1.8, which corresponds to a lactose content of about 45%, and a solids content of 50-58% in syrup obtained by condensing refined milk sugar molasses. Experimentally (It was confirmed that when the molasses of refined milk sugar is thickened to a solids content of less than 50%, the degree of crossing is below 1.7, and with a solids content of more than 58%, the degree of crossing is 1.8.

The crystallization of lactose is also affected by temperature and cooling. Lactose does not immediately crystallize and precipitates, but first remains in the redissolved state that does not correspond to its solubility. If the syrup is rapidly cooled to 1015 ° C, assuming that the solubility decreases and rapid crystallization occurs, then a high crosstalk occurs. In the region of high supersaturation, crystallization is greatly inhibited. Consequently, fast and complete crystallization of lactose cannot be achieved with rapid cooling to a final temperature. The natural cooling of the syrup to a temperature of 30–40 ° C makes it possible to obtain the optimal number of crystallization centers. Extracting the syrup at this temperature for 2-6 hours allows the largest amount of lactose to crystallize, and the crystals are highly homogeneous. The results of the crystallization of lactose at the syrup lump are presented in, tab. 1. When the syrup is lowered at a lower temperature, more crystallization prices are formed, however, their growth slows down dramatically, which leads to a decrease in the yield of the finished product due to the waste of lactose into molasses. When syrup is supplied at a temperature above AO ° C, the number of crystallization centers decreases, which also leads to a loss of lactose into molasses. At the same time, holding the syrup at 30–40 ° C makes it possible to achieve a high homogeneity of the crystals. Since milk sugar follows the general rules of solubility depending on temperature, the highest yield can be achieved at the lowest temperatures, i.e. further cooling allows the additional amount of lactose to crystallize. It is most advisable to cool to a temperature of 10-15 ° C. Deeper cooling is technically difficult. In addition, as the temperature decreases, the viscosity of the syrup increases, which negatively affects the rate of crystallization. Example 1. The molasses of refined milk sugar is concentrated on a laboratory vacuum apparatus at a temperature of 60 ° C to a solids content of 50%. The resulting syrup is divided into four parts, one of which is fed to crystallization according to a known regime (prototype), the rest

The crystals undergo crystallization according to the following mode: natural cooling to 30, 35, and 40 ° C, keeping at these temperatures using the proposed method will provide additional milk sugar in the amount of 171J8 thousand rubles. 064 value 2h. Then cooled to a final temperature of 10 ° C for 6 h. The resulting crystallized is subjected to centrifugation. The yield of the finished product, the size of the crystals, the degree of homogeneity of the crystals are determined. Comparison of the technological parameters of the finished product is carried out with data obtained by a known method (prototype). The results of changes in the technological parameters of the finished product in the two-stage crystallization mode are presented in Table. 2 and 3. Example 2. Analogously to example 1, molasses of refined milk sugar is concentrated at a temperature of 65 ° C to a content of 58% solids. The resulting syrup is also divided into four parts, one of which goes to crystallization by a known method, the rest is subjected to crystallization in the following mode: natural cooling to a temperature of 40, 35 and 30 ° C, aging at these temperatures for 6 hours. Then it is cooled to a temperature of 15 ° C for 10 hours. The yield of which product, the size of the crystals, the degree of homogeneity of the crystals are determined. Comparison of the technological indicators of the finished product is carried out with data obtained by a known method (Table 3). According to a known method for the production of raw milk sugar from molasses, its consumption of 1 ton of sugar is 15 tons. In the proposed method, by optimizing the crystallization process, the consumption of molasses is reduced to 12 tons. The yield of the finished product from 1 ton of molasses in the proposed method is 16.7 kg higher than the known one. At a cost of 1 ton of raw milk sugar 1070, this amounts to 17.9 rubles. In addition, the average crystal size and the degree of homogeneity of the crystals increase, which is important for the centrifugation process.

Table 1

The output of wet crystals per 1 kg of molasses, g

The change in the yield of wet crystals,%

The average size of the crystals, microns

Change in the average size of crystals,%

Degree of uniformity

crystals

The change in the degree of homogeneity of the crystals,%

The output of wet crystals of 1 molasses

The change in the yield of wet crystals,%

88.7

88.1

+25.4

+24.6

170

150

+30.7

+ 15.3

0.75

0.72

+36.3

+30.9

87.4

88.3

89,

+22.7

+ 2Л, 0

Average crystal size

um

The change in the average size of the crystals,% Degree of uniformity

crystals

Change the degree of homogeneity of the crystals.

1105506

8 Continuation taOl

160

150

150

+25

+33.3 +25

0.71

0.77.

0.75

+29.0

+36.3 +40.0

Claims (1)

METHOD FOR PRODUCING LACTOSE, including condensation of molasses of refined milk sugar at 60 65 ° C to a solids content of 50-58%, crystallization by cooling the condensed solution to 10-15 ° C, and centrifugation of the product, characterized in that, in order to increase yield of lactose and obtaining crystals of uniform sizes, crystallization is carried out in two stages, on the first of which the condensed molasses is cooled in natural conditions to 30-40 ° C and incubated for 2-6 hours, and cooling to ΙΟΙ 5 ° C is carried out in the second stage <d for e 6-10 hours