Process for producing 2-keto-D-gluconic acid by high-concentration fermentation

Abstract

The invention discloses a process for producing 2-keto-D-gluconic acid by high-concentration fermentation. A microorganism for converting glucose into the 2-keto-D-gluconic acid or salt of the 2-keto-D-gluconic acid is cultured in a fermentation container, as a carbon source in a fermentation culture medium, the glucose is subjected to fermentation culture, and the pH (Potential Of Hydrogen) value before sterilization is 5.5-7.0; and the fermentation culture medium consists of the following substances by massvolume: 10-32% of glucose, 0.1-1% of maize pulp, 1-5% of calcium hydroxide, 0.02-0.08% of de-foaming agent and a solvent as water. The pH value is adjusted by calcium hydroxide in the beginning of fermentation so that the cost is lower, the pH value of a fermentation solution is more accurately adjusted and controlled by liquid ammonia or ammonia water in the mid- to late-period of fermentation so that the fermentation solution is kept in the environment for optimal growth and acid production of the microorganism, and a nitrogen source is supplied at the same time, so that the acid production rate and the acid production concentration of bacteria are increased, the fermentation conversion rate and the yield are increased, the fermentation cycle is shortened, the quality of the fermentation liquid is high, the amount of the impurity is small, the extracting and purifying processes are convenient, and the emission of calcium sulfate waste residues is reduced at the same time; and the formed byproduct is ammonium sulfate which can be used as a fertilizer.

Description

technical field

[0001] The invention belongs to the field of preparation of salt synthetic precursor 2-keto-D-gluconic acid of food additives, in particular to a process for preparing 2-keto-D-gluconic acid or its salt by high-concentration fermentation. Background technique

[0002] 2-Keto-D-gluconic acid is one of the organic acids produced on a large scale in the industry at present, and it is the precursor for the synthesis of food antioxidant sodium D-erythorbate and D-erythorbic acid. The production methods of 2-keto-D-gluconic acid mainly include enzymatic method, chemical synthesis method and fermentation method. Due to factors such as production costs, the indirect fermentation technology of bacterial fermentation is mostly used in industrial production at present.

[0003] At present, in industrial production, 2-keto-D-gluconic acid is produced by fermentation, using D-glucose as raw material. The method has the following disadvantages: due to the feedback inhibi...