SU43649A1 - Getting citric acid - Google Patents

Description

Citric acid, which has a refreshing, sweet, sour taste, is widely used in the food industry. It is necessary for making soft drinks, and confectionery production is in need of it. In the textile industry, it is used for dyeing fabrics. In the production of medicines: citrated, migraine, etc., as well as in the photo are used: citric acid salts. Citric acid derivative adinol is used in engineering as a solvent for cellulose ethers in the production of varnishes.

S.P. Kostychev and his co-workers developed a method for producing citric acid by digesting sugary substances with the help of Aspfergillus niger on replaceable solutions. For the first time, Kostychev proposed the method of replacement solutions in 1902 for the study of physiological processes in mold fungi. The whole process of obtaining the maximum yield of citric acid according to Kostychez's method is divided into two stages: growth and fermentation. Mycelium flspergillus niger is grown under optimal conditions of mineral and nitrogen nutrition in a sugar solution of the following composition: water 100 cm, sugar 20 g, ammonium nitrate 0.3 g,

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magnesium sulphate 0.1 g, zinc sulphate 0.02 g, ferrous sulfate 0.02 g and potassium hydrogen phosphate 0.1 g.

After 2-3 days of growth, the nutrient solution is drained and replaced with a pure 20-25 o sugar solution, which does not contain either nitrogen or ash elements. A young, active, rapidly growing fungus, after a change of solutions, is deprived of the nitrogen and mineral salts necessary for building and immediately begins to vigorously convert sugar into citric acid. Within 3--4 days, the citric acid formation process is essentially complete. The yield of citric acid reaches 70% of the consumed and 40-50% of the total sugar in the fermentation solution.

Nutrient mixture Kostychev, Butkevich, Berngauer and others similar to her contain as a source of nitrogen ammonium nitrate. The fungus at the beginning of its development for the first two days first of all assimilates ammonia nitrogen, almost without affecting nitrate nitrogen, which is partially adsorbed by the cells. If at this moment you change the nutrient solution without carefully washing the mycelium from the adsorbed nitrate nitrogen, then the fungus produces a powerful formation of 20% sugar solution in the presence of adsorbed nitrate nitrogen

Hydrochloric acid. In fact, this explains the high yields of citric acid from the above authors. However, with thorough washing of mycelium with water of adsorbed nitrate nitrogen during solution change, the author of the present invention did not observe a noticeable increase in the formation of citric acid. If the change of solutions (with NHiNOs) is made after the assimilation of ammonia nitrogen (i.e., after the ripening of the mycelium, when it begins to age) at the moment when the fungus will actively assimilate or already use nitrate nitrogen, in this case there will be a low citric acid yield. The fact that the fermentation process actually proceeds in this way can be seen from examining experiments with Kostychev's various nitrogen sources, in which we see that mycelium grown only on ammonia nitrogen (MHjaSO., Without having been ordered after changing solutions of adsorbed nitrate nitrogen, formed An insignificant amount of citric acid and, on the other hand, mycelium grown only on nitric nitrogen KNOj, in Kostichev and NaNOg in Nardor Forges, also produced a small amount of citric acid in the fermentation solution.

The author of the present invention, after a series of experiments, has found a new method for producing citric acid. The basis of this new method was the observation of the author that the intensive formation of citric acid from sugar with the help of the fungus flspergillus niger begins only during the assimilation of nitrate nitrogen associated with the magnesium cation.

Before starting the fermentation process, the race of the fungus is activated by growing it on barley wort with the addition, as usual, of zinc and iron salts.

The selected active mycelium of the fungus flspergillus niger is transferred to a fermentation solution consisting of a 20% aqueous sugar solution with the addition of magnesium nitrate, alone or mixed with potassium nitrate.

Example. Processing barley wort. Incomplete barley wort produced by breweries

in the usual way and containing at least carbohydrates, it is heated until, under these conditions, some coagulated proteins and colloidal wort substances precipitate. The precipitate is separated by wort sedimentation or filtration through a dense web. The wort sediment is used to produce a spore suspension, and the filtrate is used to grow the active mycelium.

Getting spore suspension. In 100 cm of tap water, 5 cm of untreated wort and 5-10 g (wet weight) of wort sludge are added; the mixture is agitated, poured into flat-bottomed flasks, sterilized and contaminated abundantly with fungal spores. During three days at 30 ° a thin film of the mycelium is spread on the surface of the solution (layer -2 cm), completely covered with spores. Thereafter, the mixture is drained and the mycelium is washed once with tap water. Then as much water is added as the nutrient mixture; the added water is vigorously agitated with mycelium and a spore suspension is obtained.

Growing active mycelium. Tap water is poured into a cuvette with a layer of 1 cm and 25 ° C of the filtrate of the treated wort, 0.005 ZnSOi and O.OOZO / o FeClj is added, spore suspension is added at the rate of 10 cm for every 100 c i of the nutrient solution and the tire is put on the cuvette. After two days (at 30 °) of the growth of the mycelium, you can begin to change the nutrient solution to fermenting.

Preparation of fermentation solution. 20 / ozahara, 0, (CUz) oH, O and 03 ° / o KNOg are added to tap water. The solution of magnesium nitrate should give a very acidic reaction. If not, it is necessary to acidify the solution.

Change of solutions and control of the fermentation process. The fermentation solution consists of a solution of sugar with an addition of 0.35% magnesium nitrate and 0.3% / of potassium nitrate acidified with nitric acid to visibly acidic reaction.

The nutrient solution on which mycelium is grown is drained and mycelium

rinsed twice with tap water. After that, the fermentation solution is poured in and the tires are put on the cuvettes. The lid on the cuvette must be arranged in such a way that aeration, heat transfer and evaporation are hampered. These requirements are obviously satisfied by tires made of linen or a thin cotton wool fabric. By periodic sampling, the time when the sugar content reaches 3-4% is determined. By this time, the fermentation is mostly complete. The fermentation solution is then withdrawn to a special compartment, where citric acid is obtained in the form of a calcium salt and, after treatment with sulfuric acid, is isolated in the form of crystals.

During the change of fermentation solutions, the mycelium is rinsed 1-2 times with water. In this way, 4 changes of the fermenting solution are made, after which it is necessary to re-grow the active mycelium. Particularly complex devices for changing solutions are not required. In his experiments with the cuvettes, the author of the present invention wrapped the edge of the mycelium with tweezers and poured the fermentation solution from the glass.

The efficiency of citric acid production in a new way.

With a cuvette working surface of 1 m and a layer thickness of 1 cm, 1 shift of 10 liters of fermentation solution containing 2 kg of sugar will be required per shift. In this case, it will be obtained, considering the 50% yield for the whole sugar consumed by the production, 1 kg of citric acid. There may be 80 such shifts per year, which will require an LLP of a kg of sugar with a yield of 80 kg of citric acid. With the projected annual capacity of the Leningrad citric acid plant at 50 / ha of citric acid, the proposed method will be required.

600 m - working surface and 100 m of sugar.

When comparing the effectiveness of the proposed method with the method tested by S. P. Kostychev already in semi-industrial conditions, the following results are obtained:

Fermentation by the method of Kostychev leads for 7 days on a permanent solution. Citric acid yields, on average, 20% for all sugar consumed. The height of the layer is 1.5 cm. In a year, the working surface of the oil can be only 52 turns, which would require 156 kg of sugar with a yield of 31.2 kg of citric acid. To obtain 50 tons of citric acid according to Kostychev's method, the plant will need 1600 m of working surface and 250 tons of sugar.

If we apply the proposed method, then from the same 250 tons of sugar with a working surface of 1500 m, 125 tons of citric acid will be obtained. Net savings equal to 75 tons of citric acid. At world market prices of 3,000 marks per ton of citric acid, the state will receive 225,000 marks in gold currency for every 50 tons of citric acid.

The subject matter of the invention.

The method of obtaining citric acid by fermenting sugar with preselected races of the fungus flspsrgiilus niger, characterized in that the selection of the active races of the fungus is made by growing their mycelium on barley wort, from which proteins and colloidal substances are removed, heated to 110 °, after which The salted wort is supplemented with zinc and iron salts, and the selected mycelium is used to ferment sugar to citric acid in the presence of magnesium nitrate.