Study On Liquid Fermentation Of Mucor Mucedo(L..) Fres And Safety Evaluation Of Sufu

Mucor mucedo(L..) Fresis,an excellent strains brewed in sufu,mainly for the production of sufu by the traditional means,solid fermentation,but it had not been reported growth characteristics and application in the liquid conditions.In order to improve on the traditional techniques of strain-fermentation in the production of fermented sufu,the liquid growth conditions of MHC-7 is studied. According to the production principle of the selection and compound of microbiologic medium,using yellow swill,the byproduct in the production of fermented tofu,as the solvent,via the single element and orthogonal experiment,the optimum medium is determined:shaking with 28℃,200 rpm,3%soybean powder,0.4%soluble starch, 0.2%magnesium sμlfate,0.2%potassium dihydrogen phosphate,0.3%sucrose and Soymilk.The adequate C/N ratio in medium is abuat 1.5.The initial optimal inoculum is 6%and pH is 6.Through biomass determination,the fermentation in liquid reached the maximum value in the 36 hour(1.363g/100ml).This experiment concentrated on the change rules of the enzyme activity and chemical composition during the fermentation.The results show:the best fermentation cultivation time of MHC-7 is 34h-38h.The biomass of MHC-7 was able to reach respectively 22.8g/100ml(wet weight of mycelia) at 30h in the 19L general fermentor.This means the fermentation cycle of the sufu is shortened by 4-8h.The best fermentation time of MHC-7 in the beans billet is 32-34h.Within the late 45 fermentation days of sufu,all kinds the activity of enzyme falling,but glutaminase were declining as the time increasing.Conversely the glutaminase activity was growing continuously,resulting in the growth of the flavor of sufu.So when the content become as this:glutaminase(76.5μ/g),total acid(1.0%),and Viscosity (2×10~5mpa.s),this sufu is mature on the whole.In order to enhance the safety of fermented sufu,we determine aflatoxinB1, ochratoxinA,sterigmatocystin,fumonisinB1 and staphylococcal enterotoxin,which maybe be infected in the production of fermented sufu in Guizhou province,and the safety evaluation of sufu.The results show that the content of toxin producted in Guizhou province were below the minimum detection limit of the national standard.It was fully consistent with national food safety requirements.But the content of toxin of the bulk sufu on the market exceeded the standard.