Studied On The Optimization Of The Process Technics Of Bean Paste

This paper used naturally-fermented broad beans which13Village Food Co.Ltd,hunan province provided as raw materials,analyzed the dominant microbial in the broad beans,artificially inoculated fermentation was token,and artificial inoculation conditions were optimized with response surface,compared the effect that bean paste was fermented under different temperature patterns.At last,optimized the condition of produced neutral protease,and studied the characteristics of Aspergillus oryzae protease, results were as follows:(1) Isolation and culture with various medium,counted bacteria,Bacillus,yeast,mold on grains beans and identify mold preliminary. The results indicated that mold which were isolated from grains beans were determined as Aspergillus oryzae and Mucor racemosus fracemosus. the number of them was2.8×107cfu/g.3.0×106cfu/g respectively.the number of bacteria and yeast was5.3×104cfu/g,2.6×102cfu/g respectively; Bacillus:not detected.(2) Optimized fermentation condition of artifical inoculated koji with Aspergillus oryzae which isolated from natural inoculated koji,and compared the neutral protease activity,total acid,ester that bean paste was fermented under different temperature patterns:mode(1)constant temperature:fermented at35℃for30days, mode(2)from high temperature to low temperature:50℃for10dâ†'40℃for10dâ†'30℃for10d,mode(3)from low temperature to high temperature:30℃â†'10dâ†'40℃for10dâ†'50℃for10d.The results indicated:In the process of koji,inoculum size was0.36%,cultivated temperature was32.5℃.cultivated time was46.85h,under this optimized conditions,the neutral protease activity of koji reached508.78u/g.Under temperature mode of30-50℃,the amino nitrogen content were more than traditional fermentation by80%,total acid content were less than20%traditional fermentation. This temperature fermentation pattern was superior to the traditional fermentation mode.The production of bean paste in the amino nitrogen,total acid,salt content and health indicators are in line with national standard(GB2718-2003).(3) An Aspngillus oryzae strain was isolated and purified from bean sauce and the suitable conditions for the production of neutral protease are studied,the conditions are cultivation temperature at20℃,25℃,30℃,35℃,incubation time20-96h culture initial pH3,4,5,6,7.5,10.5conditions under m Aspergillus neutral protease activity,The results indicate that the productivity of neutral protease is the highest.The suitable composition of medium is as follow:m(wheat bran):m(water)=1:1,Yeast extract2.00%,peptone0.20%, KNO30.1%, maltose0.1%, glucose o.l%, (NH4)2SO42%.The optimal cultural temperature is30℃,culture duration72h.Under this optimal conditions,the neutral protease is as high as12113.85u/g,increased22.98%then before optimization,increased nearly doubled than AS3.042(5000-6000u/g).(4) The enzyme characters of neutral protease of Aspergillus oryzae isolated from bean paste were studied.The results show that the maximum activity reaction of neutral protein enzyme was at55℃,the optimum pH was7.5,the thermal stability was relatively stable in the40-45℃,when the temperature exceed50℃,the thermal stability quickly declined,the effect of sodium chloride content to Aspergillus oryzae neutral protease activity was very significant. With the the sodium chloride content increase,the activity of e decreased,when the sodium chloride content reached21%,the relative enzymatic activities of neutral enzyme only26.91%,Mn2+to the protease activation,the relative enzyme activity as the control of171.843%; Fe2+for their performance strongly inhibited, the relative activity to almost zero.