SU69300A1 - The method of obtaining citric acid - Google Patents

Description

In the presence of certain mineral salts, many types of molds on solutions of sugar and sugar-like substances convert part of the sugar to citric acid. Asperqillus niger mold is particularly good as an acid former when it is set in appropriate conditions. Optimal conditions are known for producing citric acid by fermentation from sugar, and there are industrial plants for producing citric acid by this method.

It has also been proposed to obtain citric acid from chalk sci with the help of specially selected Aspergillus niger devices.

However, the content of large amounts of salts and other impurities in the chalk is harmful for the acidifying agent on the microorganism and the yield of citric acid is low.

The author has clarified the conditions necessary to significantly reduce the sensitivity of Aspergillus niger to chalk sse and such

way to significantly increase the yield of citric acid.

According to the proposed method of obtaining citric acid from melted sugar by fermentation, the Aspergillus niger strain selected in the usual way by Aspergillus niger strain is passed through a series of artificial nutrient media with gradually increasing melon content to develop resistance to chalk. .

The following is a generic scheme for the production of citric acid from chalk chalk.

1. Derive and cultivate a clean line of selected Aspergillus niger strain capable of growing on media with a pH of 2.0-1.8.

The pure culture removed from one conidia is kept on ice under sterile conditions and renewed 2-3 times during the year.

When a culture is renewed, it is carried out through a cycle of artificial nutrient media with a gradually increasing content of chalk

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PH environment b-5,5. Then a quantity is taken from it, for example, 10 parallel screenings, which are checked for acid-forming ability, fermentation rate and the presence of off-acid in the waste. The best-performing culture — as a clean line — is maintained until the next update, and the rest are discarded.

2. For the production of citric acid, the main culture is propagated on suitably large surfaces to obtain the required amount of conidia going into production for grafting in the form of suspension or dry dust mixed with indifferent fine material, for example talc.

3.Mixer brews intended for fermentation are prepared in the usual way: after dilution in the ratio of 1: 3 with tap water, bleach coal, infusorial earth and sulfuric acid are added to pH 5.6 and heated at 65 ° C and gradually stirred for 1 hours, then quickly brought to a boil and immediately filtered through an asbestos filter.

After cooling, solutions of the corresponding nutrient salts and sulfuric acid to pH 1.8-2.0 are added to the resulting solution.

The chalk solution prepared in this way after the corresponding

dilutions are used as a fermentation solution. To the first fermentation solution, on which it is necessary to develop mold micelles, a 10–12% sugar solution is added to accelerate the development of the micelles.

4. Fermentation is carried out at a temperature of about 25-35 with constant blowing of fresh and saturated with water water, air in flat vessels at a height of a layer of liquid 2-4 cm at rest or when shaking with a periodic or continuous slime fermentation solution.

5. The fermented solutions are treated with chalk at reflux to precipitate calcium citrate. After washing with hot water, calcium citrate is decomposed with sulfuric acid, the citric acid solution is separated from calcium sulfate and concentrated by evaporation in vacuum in 2 steps before crystallization.

The subject of the invention is a method for producing citric acid from chalk brewing by fermentation, characterized in that a culture of microorganisms is used for fermentation, which is obtained by posting the strains selected in the usual way through a series of artificial nutrient media with gradually increasing content of melted bread.