RU2464321C2 - Milk sugar production method - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: method involves whey clearing from fat and protein, condensation till dry substances content is equal to 45-60%, with subsequent crystallisation of lactose. Cristallisation is performed by way of tree-time cyclic heat treatment of the crystallisate; the treatment consists in sequential heating and cooling in each cycle with subsequent separation and drying of lactose crystals. In each cycle heating is performed up to a temperature equal to 75 - 80°C while cooling is performed to a temperature equal to 10°C.

EFFECT: product weight yield increase and production time reduction.

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Description

The invention relates to a technology for the production of milk sugar - lactose.

A known method of crystallization of lactose from whey obtained in the production of cottage cheese or cheese by purification of fat and proteins by thermal and acid-base coagulation, then the whey is sent to thicken in a vacuum evaporator to a mass fraction of solids of 50-54% and served purification from non-sugars of organic and mineral origin by one of the known methods. The purified syrup is first cooled to 10-12 ° C for 8-10 hours, and then kept at this temperature for 10-12 hours [1].

The disadvantages of this method compared with the claimed are the low yield of milk sugar and the long duration of the process of crystallization of lactose.

The problem to which the invention is directed, is to reduce the time for the process and increase the mass yield of the product.

The problem is solved through the application of a method for the production of milk sugar from whey, including purification of whey from fat and proteins and thickening, followed by crystallization of lactose, separation and drying of lactose crystals, characterized in that the process of crystallization of lactose from condensed to 45-60% dry serum substances is carried out by cyclic heat treatment, consisting in its sequential heating and cooling.

Prepared and condensed in a known manner [1] whey is subjected to cyclic heat treatment, consisting in its sequential heating and cooling, and in the first cycle, the syrup is heated to a temperature of 75-80 ° C for 1 hour, and then cooled to a temperature of 10 ° C within 3 hours. This is followed by a second cycle of 3-hour heating from 10 ° C to 75-80 ° C, followed by 3-hour cooling from 75-80 ° C to 10 ° C. The third cycle repeats the second.

увеличивается с ростом приведенного линейного размера кристалла d:The technical result consists in the fact that due to the introduction of cyclic heat treatment of whey, an increase in the yield of crystallomass is achieved as a result of a more intensive crystallization process. When the crystallizate is heated, small crystals dissolve. The smaller the size of the crystal, the less time it dissolves when heated. Larger crystals do not have time to dissolve during heating. In this case, the concentration of the solution increases, due to which the growth rate of large crystals increases, which do not have time to dissolve during the heating of the crystallizate. The effect is achieved due to the fact that the linear growth rate of lactose crystals

increases with increasing reduced linear crystal size d:

where: d is the averaged reduced linear crystal size, m;

ρ _{to the} density of the crystal, kg / m ³ ;

g is the acceleration of gravity, m / s ² ;

ρ _W - the density of intercrystal fluid, kg / m ³ ;

µ - dynamic viscosity, intercrystal fluid, Pa · s;

ΔC = C _n -C _n - supersaturation of the crystallizate, kg / m ³ ;

With _n and With _n - the concentration of supersaturated and saturated solutions, respectively, kg / m ³ [2].

From formula (1) it is seen that the growth rate of the lactose crystal W is proportional to the square of its linear size d. When the crystallizate is heated, the dissolution of small crystals leads to an increase in the concentration of the solution С _n , and therefore to an increase in its supersaturation ΔС. An increase in all of the above parameters, and especially the linear crystal size (due to the quadratic dependence of the growth rate on the linear size), increases the growth rate of lactose crystals. In addition, the dissolved small crystals partially retain their structure in the dissolved state, forming clusters, and create favorable conditions for the crystallization process, namely: they easily attach to large crystals, intensifying their growth [3]. All these three factors, namely: the dissolution of small crystals with the formation of cluster-like clots, an increase in the concentration of the solution and an increase in the size of the crystals, make it possible to intensify the crystallization process. The result is large, homogeneous crystals of milk sugar. An increase in the size of the obtained crystals and a decrease in the heterogeneity of their particle size distribution provide an improvement in the centrifugation conditions of the crystallizate. This reduces the loss of lactose in molasses, due to the ingress of small crystals into the intercrystal solution during centrifugal separation of the precipitate, since the number of small crystals in the mold is reduced.

As a result, the yield of milk sugar per ton of initial whey increases from 20 to 25 kg due to an increase in the average crystal size and the amount of crystallized lactose. The effect is achieved due to a decrease in the number of crystallization centers, an increase in the linear size of growing crystals, an increase in the concentration of a supersaturated solution, and the formation of cluster-like structures from small lactose crystals when the syrup is heated.

Example. Serum purified from casein dust and fat, which underwent the procedure of protein precipitation by the acid-base method in an amount of 250 kg, was condensed on a VIGAND circulation vacuum evaporator at a temperature of 60 ° C to a solids content of 52%. The obtained 25 kg of condensed whey (crystallizate) was poured into a crystallizer with a heating and cooling jacket and mechanical stirring, where, by supplying hot water to the jacket (t = 80 ° C), heating was carried out for 1 hour to a temperature of 75 ° C. Then the crystallizate was cooled with ice water (t = 2 ° C) for 3 hours to a temperature of 10 ° C with constant stirring. Subsequent heating and cooling cycles of the crystallizate lasted 3 hours with a similar temperature variation of 10-75 ° C. After cooling in the 3rd cycle, 16 hours after the start of the crystallization process, the average crystal size was 310 microns. The amount of raw sugar obtained after filtration and drying is 6.25 kg.

As a result of the use of the proposed technology for processing whey, the yield of milk sugar is increased by averaging the particle size distribution of crystals and increasing the average crystal size. In addition, the time of the crystallization process is reduced.

Information sources

1. AS of the USSR No. 249178, cl. 53 e, IPC A23C, 1969

2. Fialkova EA, Kulenko VG, Kachalova EA, Kostyukov EM The theory of growth of lactose crystals depending on their size // Sat. materials of the international scientific and technical seminar "Modern directions of whey processing". Stavropol: Educational Institution “Educational Scientific and Technical Center of the Dairy Industry”, 2006. - P.57-58.

3. Koltsova E.M., Aganina A.V., Gordeev L.S. A cluster crystallization model that predicts order and chaos // Journal of Physical Chemistry, p. 74, No. 5, p. 888-895.

Claims (1)

A method for the production of milk sugar from whey, including the purification of whey from fat and proteins, its thickening to 45-60% solids, followed by crystallization of lactose by triple cyclic heat treatment of the crystallizate, which consists in sequential heating and cooling in each cycle, followed by separation and drying lactose crystals, with heating in each cycle to a temperature of 75-80 ° C, and cooling to a temperature of 10 ° C.