| 摘要 |
Citric acid is produced by fermenting in the presence of iron and zinc salts, a carbohydrate solution containing nutrient inorganic and nitrogenous material, with a surface aerobic growth of Aspergillus wentii. In the example, a culture medium containing cane sugar, ammonium nitrate, peptone, magnesium sulphate, dipotassium hydrogen phosphate, potassium chloride, zinc sulphate, ferric chloride and calcium chloride is sterilized with heat and inoculated with an aqueous supension of sporres or pregerminated spores of A. wentii, grown on a medium containing peptone, glucose, dipotassium hydrogen phosphate, magnesium sulphate and agar. When a white surface pellicle of the fungus is obtained, the residual culture medium is drawn off from below and replaced by a fermentation solution containing 15-20 per cent of carbohydrates in the form of sucrose, maltose, lactose, glucose, dextrose, levulose, invert sugar or sugar of molasses. The pH of the solution is maintained at 3.0, by the addition of calcium carbonate or an alkali metal hydroxide. Fermentation is carried out either in very shallow vessels or in deeper vessels where air is pumped under pressure through the fermentation solution. Specification 568,508 is referred to.
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