RU2090618C1 - Method of producing monosugars from their mixture - Google Patents

Abstract

FIELD: food industry. SUBSTANCE: method involves hydrolysis of the milled carbohydrate-containing raw with 0.5-5.0% sulfuric acid solution at 95-135 C for 1.5-3 h. Then urea is added at ratio to raw weight (1:8)-(1: 40), by mass. Mixture is kept at the same temperature for 30-60 min, neutralized, cooled and solution is separated from precipitate followed by purification, evaporation, sugar crystallization with ethanol at ratio (1:1)-(1: 2) with evaporated solution at 10-20 C for 2-8 h. Crystals were separated by centrifugation, washed with ethanol and dried under vacuum at 20-45 C. EFFECT: improved method of producing.

Description

 The invention relates to the production of monosaccharides from vegetable carbohydrate-containing raw materials and can be used in their industrial production for food, pharmaceutical, cosmetic and other industries.

 Recently, a number of studies have established the influence of monosaccharides on the regulation of the immune system of the human body, their introduction into the diet reduces the possibility of diseases such as ischemia, gout, diabetes, etc. This necessitates the industrial production of monosaccharides and their mixtures.

 The most promising is the receipt of these products from affordable and inexpensive plant materials. It is known that in the domestic flora there are plants with a high content of polysaccharides, for example legumes, licorice roots, acacia gledichiya, etc.

 A known method of producing galactomannans from plant materials containing carbohydrates / B. D. Sherbukhin. Galactomannans of domestic flora. Applied Biochemistry and Microbiology. T. 29, 1933, p. 803 813 /.

 The method is carried out by extraction of crushed raw materials with boiling 85% ethanol / 40-60 min /, followed by precipitation of the product with ethanol and separation of the precipitate by centrifugation. This procedure is repeated several times. After this, the precipitate is purified by Feling’s reagent, the product is separated from the copper complex solution with dilute hydrochloric acid, ethanol dehydration and drying.

 This method is not feasible in an industrial environment, does not provide the output of monosaccharides.

 Known methods of processing various plant materials (straw, bark, etc.) for animal feed by hydrolysis of the crushed raw material with sulfuric acid with the addition of a catalyst / metals, urea / in order to increase the content of monosugars in the feed / a.c. USSR N 651652, A 23 K 1/12, 1979; A.S. USSR N 1713538, A 23 K 1/12, 02.23.92. Bull. N 7 /.

 However, these methods do not provide for the production of monosugars and their mixtures in pure form for use in food, pharmaceutical and other industries.

 Closest to the claimed is a method for producing D-mannose from carob beans / G.V. Lazurievsky et al. Practical work on the chemistry of natural compounds. M. Higher School, 1966, p. 58 /.

 The method includes hydrolysis of crushed raw materials with sulfuric acid when heated in a water bath for 9 hours, cooling and separating the hydrolyzate by centrifugation, neutralizing the solution with barium hydroxide, cleaning with activated carbon during boiling, filtering in hot form and evaporating to obtain a precipitate. Purification of the product is carried out by recrystallization with glacial acetic acid and washing with methanol and ether. The disadvantages of the method are the complexity and multi-stage cleaning process, the difficulty of implementing the technology in an industrial environment, the inability to use the resulting sugars as a food additive / due to the use of methanol and ether /.

 The aim of the invention is to provide the possibility of industrial production of monosaccharides and mixtures thereof from vegetable carbohydrate-containing raw materials for use in the food and pharmaceutical industries, reducing costs.

This goal is achieved by the fact that hydrolysis of the crushed carbohydrate-containing raw materials is carried out with a 0.5 5.0% solution of sulfuric acid at 95 - 135 ^o C for 1.5 3 hours, then urea is introduced in the ratio with the weight of the raw material 1: 8 1: 40 by weight, kept at the same temperature for 30-60 minutes, the mixture was neutralized, cooled, the solution was separated from the precipitate, purified, evaporated, sugar was crystallized with ethanol in a ratio of 1: 1 1: 2 with an evaporated solution at 10 20 ^o C for 2 8 hours, the crystals are separated by centrifugation, washed with ethanol and dried in vacuum at 20 - 45 ^o C.

 In relation to the prototype, the invention has the following distinctive features.

The hydrolysis of the acid with a lower concentration / 0.5 5.0% / at a higher temperature / 95 135 ^o C / while reducing the time to 1.5 3 h provides a reduction in heat consumption and acid consumption.

 The introduction of urea increases the yield of monosugars and accelerates the process of hydrolysis. When heating plant materials in a solution of sulfuric acid, the lignin-cellulose complex is destroyed and the easily hydrolyzable carbohydrates pass into an acidic solution. Urea catalyzes the hydrolysis of hemicellulose. The urea solution has the basic properties, but its aqueous solutions have a neutral reaction. Therefore, the acid solution is neutralized with an equimolecular alkali solution.

The urea complex with acids decomposes above 152 ^o C, therefore, in the claimed temperature ranges of hydrolysis does not decompose urea to carbon dioxide and ammonia.

 Crystallization of sugars in an evaporated solution with ethanol in a ratio with a solution of 1: 1 1: 2 provides an increase in the purity and yield of the finished product, suitable for food additives.

 Separation of crystals by centrifugation increases the yield of the finished product, washing with ethanol preserves nutritional properties, drying in a vacuum preserves the purity and structural properties of monosugars.

 The possibility of practical implementation of the invention is confirmed by examples of specific performance.

Example 1. The crushed legume fruits weighing 100 kg are placed in a 1 m ³ reaction vessel, 500 kg of a solution of 0.5% sulfuric acid are poured by weight, heated with dry steam to a temperature of 135 ^o C, thoroughly mixed and kept for 1, 5 hours. After 1.5 hours of hydrolysis, 2.5 kg of urea are introduced into the mixture, mixed thoroughly and held for 30 minutes at the same temperature, and after 30 minutes 40 liters of a saturated solution of 5 kg of barium hydroxide are introduced, the reaction mixture is cooled, mix thoroughly for 2 hours, check the pH of the medium, which should be be in the range of 5.5 6.5.

The neutralized solution is separated from the precipitate in a centrifuge, purified with activated carbon, evaporated using a vacuum evaporator in 2/3 of the volume at a temperature of 60 70 ^o C and 1: 1 is added to an evaporated solution of 96 ^o ethanol to precipitate sugars in solution. After keeping the solution with sugar crystals at a temperature of 20 ^o C for 8 h, the obtained crystals are separated by centrifugation at 3000 13000 rpm, washed with 96 ^o ethanol and the precipitate is dried under high vacuum at a temperature of 45 ^o C.

Monosugar yield is 20%
Example 2. The preparation of monosaccharides is carried out analogously to example 1, except that the crushed husk from buckwheat is subjected to hydrolysis, hydrolysis is carried out with 5% sulfuric acid at 100 ^° C for 2 hours, 12.5 kg of urea are added and incubated for 40 minutes crystallization is carried out at a ratio of one stripped off solution and ethyl alcohol of 1: 2 at 15 ^o C for 6 hours and dried at 25 ^o C. The yield of monosugars was 15%
Example 3. The preparation of monosaccharides is carried out analogously to example 1, except that the crushed licorice roots are hydrolyzed, hydrolysis is carried out with 2% sulfuric acid at 95 ^° C for 3 hours, 10 kg of urea are added and kept for 60 minutes, crystallization is carried out at the ratio of one stripped off solution and ethyl alcohol 1: 1.5 at 20 ^o C for 2 h and dried at 45 ^o C. The yield of monosugars was 5%
Example 4. The preparation of monosaccharides is carried out analogously to example 1, except that the hydrolysis is subjected to crushed fruits of gledicia tricuspid / acacia gledicia /, hydrolysis is carried out with 1% sulfuric acid at 120 ^o C for 2.5 h, add 10 kg of urea and stand for 45 minutes, crystallization is carried out at a ratio of one stripped off solution and ethyl alcohol of 1: 2 at 15 ^o C for 6 h and dried at 20 ^o C. The yield of monosugars was 15%
As shown by experimental data, with a decrease in sulfuric acid concentration, temperature, and hydrolysis time below the stated limits, the lignin-cellulose complex is not destroyed, exceeding the declared limits is impractical and will lead to an increase in heat costs and acid consumption.

 The introduction of urea earlier than 1.5 hours into the reaction medium does not lead to a catalytic effect, since the lignin-cellulose complex with acid is still not sufficiently destroyed.

 The introduction of urea after 3 hours into the reaction mixture leads to excessive energy consumption and decomposition of arabinose, mannose and some other labile sugars.

 Holding the reaction mixture with urea for less than 30 minutes leads to less accumulation of simple sugars, which confirms the insufficient catalytic activity of urea.

 Sustaining the reaction mixture with urea for more than 60 minutes leads to sugar deconstruction, resulting in the accumulation of pentoses, not hexoses, and the products of the interaction of sugars with urea, glycosylurea, galactosylurea, etc.

 In the claimed limits of the ratio of urea and solids, the highest catalytic activity of urea is observed, with exorbitant values, the sugar yield decreases.

 When reducing the amount of ethyl alcohol, the exposure time below the declared limits of sugar crystallization does not occur, exceeding the claimed parameters is impractical.

 Thus, the invention is practicable, its use will allow to organize the industrial production of monosaccharides for food and pharmaceutical additives from inexpensive and affordable raw materials.

Claims (1)

A method of producing monosugars and mixtures thereof from vegetable carbohydrate-containing raw materials, including hydrolysis of crushed raw materials with sulfuric acid, neutralization of the hydrolyzate, separation of the precipitate, purification of the solution, evaporation, crystallization of sugars and their washing, characterized in that the hydrolysis is carried out 0.5 to 5.0% an acid solution at 95 135 ^o C for 1.5 to 3.0 hours, then urea is introduced in proportion to the raw material of 1 8 40 by weight, kept at the same temperature for 30 to 60 minutes, cooled, and the sugars are crystallized with ethanol in the ratio of evaporated races sugar mixture 1 1 2 at 10 20 ^o C for 2 8 h, the crystals are separated by centrifugation, washed with ethanol and dried in vacuum at 20 45 ^o C.