Study On The Process Of Potato Production By Fermentation Of Citric Acid

The citric acid fermentation is the main raw material for starchy raw materials, mainly in the corn as raw material, but with the corn and other raw materials prices rise, we should suit one’s measures to local conditions select the appropriate raw materials, reduce the cost of citric acid production. In this experiment, potato as raw materials, and citric acid by Aspergillus niger fermentation method, enhances the value of potato products deep processing. The Aspergillus niger fermented potato producing citric acid were studied comparing, Aspergillus niger fermentation to produce citric and select the acid medium and fermentation conditions were optimized. Specific conclusions are as follows:(1) Starting from Co827, TD-0168and NJUE-8three kinds of Aspergillus niger, through fermentation test, fermentation ability of three species of raw material is different. The Aspergillus niger Co827acid yield the highest, reaching11.1%. Then TD-0168, acid production reached10.3%, NJUE-8relative acidity the lowest, only9.2%. So the selection of Co827, two strains were screened for TD-0168. The final selection of acid producing high and short period of Co827as an experimental strain.(2) Through the comparison of high temperature cooking process and extrusion puffing method for pretreatment of raw materials, using shake flask test, determination of the initial reducing sugar and acid amount under the same conditions, the selection of raw material processing method for high temperature cooking acid production stable and high.(3) With the high temperature steaming pretreatment method, the same experimental conditions, the liquefaction temperature and liquefaction enzyme liquefaction conditions and additives on the test liquid velocity were investigated, liquefaction temperature is85℃, addition amount of liquefied enzyme35u/g.(4) The culture medium of Aspergillus niger Co827, the single factor and orthogonal test optimization:The optimum concentration of carbon is20%; the best choice of nitrogen sources are inorganic nitrogen physiological acidic ammonium chloride, concentration is1%; the optimum concentration of acid promoter is0.3%, the best effect. Based on establishing the optimal medium formula, some control conditions of some common laboratory of fermentation caused by fluctuations, the single factor experiment and orthogonal optimization test of, test results:The initial pH in6; fermentation temperature at32℃, because the table has some fluctuation, can be controlled in a certain range; the range between240r/min, acid production is stable.