Screening Of High-yield Caproic Acid Bacteria In Luzhou-flavor Liquor And Mud Liquid Preparation

The main body flavor of Luzhou-flavor liquor is ethyl caproate,which esterifies from caproic acid and ethanol.During the processing,the quality of Luzhou-flavor liquor is directly related to the quantity and quality of caproic acid producing strain in pit mud.Researches on the screening and application of high-yield caproic acid bacterium in the pit mud have great significant on expanding superiority functional flora,promoting aroma-producing function of fermenting system and high quality productive rate.Some functional strains are selected from the pit mud of some distillery in the northeast area,and then be applied to the preparation of liquid fermentation pit mud.After that,species identification is carried out through morphological observation,physiology biochemistry experiment and molecular biology methods.The primary liquid fermentation pit mud is prepared through experiments to the obtained functional strains.By using response surface method,the optimum parameters are determined to obtain high quality liquid fermentation pit mud.Three strains of high-yield caproic acid bacterium selected from the pit mud that yield caproic acid 103.5098 mg/100mL,170.465 mg/100mL and 213.6914 mg/100mL respectively are A17,a57 and C78.The identification shows that A17,a57 and C78 are Bacillus fusiformis,Bacillus licheniformis and Bacillus megaterium respectively.The optimum inoculum sizes of these three strains to formulate the primary liquid fermentation pit mud are determined by experiments with 4%,5%and 6%respectively.By using response surface method,three main influencing factors are found out (ethanol,MgSO4 and Daqu powder),and the optimist concentration of these three factors ethanol 2.01%,MgSO4 0.01%and Daqu powder 4.18%.Under such condition,the liquid fermentation pit mud own the best quality,with cell concentration of 94.47×107 cfu/mL.