Study On Technology Optimization And Flavor Substance Of Sour Beer

With the improvement of people's living standards,industrial beer has been unable to meet people's needs,craft beer is rising,sour beer is the high-end product of craft beer,so the research of sour beer has a good guiding role in the estimation of craft beer market.In this paper,Lactobacillus plantarum,Lactobacillus acidophilus and Lactobacillus bulgaricus were selected for the acidification process.Through single factor analysis,taking the p H value of acidified wort as the evaluation index,the effects of orginal gravity,acidification temperature,inoculation amount and acidification time on the p H value of acidified wort were studied,combined with orthogonal experiments to determine the optimal acidification process for different acidifying strains parameter.The following conclusions were drawn:(1)the optimal acidification process parameters of Lactobacillus plantarum were the orginal gravity of 14°P,the acidification temperature of 37?,the acidification time of 72 hours,the inoculation amount of 1×10~7CFU/m L,the final acidified wort p H value was 3.70;(2)the optimal acidification process parameters of Lactobacillus acidophilus were the orginal gravity of 12°P,the acidizing temperature of 35?,the inoculation amount of 1×10~7CFU/m L,the acidification time of 72 hours,the final acidified wort p H value was 3.58;(3)the optimal acidification process parameters of Lactobacillus bulgaricus were the orginal gravity of14°P,the acidizing temperature of 42?,the inoculation amount of 1×10~7CFU/m L,the acidification time of 72 hours,the final acidified wort p H value was 3.47.Then select the best acidification process parameters of each acidification strain to acidify the wort.Compare and analyze the indexes of three kinds of acidification wort,and the following conclusions were drawn:the content of lactic acid and the number of lactic acid bacteria in the acidification wort of Lactobacillus bulgaricus were higher than that of Lactobacillus plantarum and Lactobacillus acidophilus,and the p H value was also the lowest,which proves that its acidification performance was the best,so Lactobacillus bulgaricus was the most suitable strain for wort acidification,which was used in sour beer brewing.Then the effects of two brewing methods on the quality of sour beer were compared,which were 1:1,1:2,1:4 mixing ratio of acidified wort and normal fermented beer,and boiling and adding hops directly after the acidification of wort.Through the sensory evaluation,physical and chemical index determination and flavor substance analysis of different finished sour beer,the following conclusions were drawn:(1)The finished sour beer brewed by the way of acidified wort and boiling directly and adding hops was outstanding in appearance,high carbonation,flavor coordination and acid sense,the ester flavor and mellow sense also reach the standard,and the foam holding was slightly poor;it was obviously better than the sour beer brewed by acidified wort and normal fermented beer according to the appropriate proportion;(2)The real fermentation degree of the finished sour beer brewed by direct boiling and adding hops after the acidification of wort was 78.5%,which was higher than that of other finished sour beer and has the lowest diacetyl content,and other indexes meet the requirements of the national standard;(3)The finished sour beer brewed by direct boiling and adding hops after the acidification of wort has the richest organic acid content,the highest ester content,ethyl acetate,isoamyl acetate and ethyl lactate were higher,11.75 mg/L,0.65 mg/L and 28.79 mg/L,respectively.In summary,Lactobacillus bulgaricus was the most suitable acidifying strain for sour beer brewing.the method of brewing sour beer by directly adding hops after the acidification of wort was the best sour beer brewing method.On this basis,the effects of fermentation temperature,yeast inoculation amount and hop addition on the sensory evaluation of sour beer were compared by single factor analysis,combined with response surface analysis to optimize the brewing process parameters of sour beer.The optimal brewing parameters of sour beer were:fermentation temperature 21.4?,yeast inoculation amount 1.51×10~7CFU/m L,hop addition amount 1.2‰,the sensory score of the finished sour beer brewed under this process parameter condition was 92 points;the orginal gravity of the finished sour beer was 14.05°P,the alcohol degree was 5.92%,the real fermentation degree was 85.3%,the p H value was 3.52,diacetyl and other physical and chemical indicators were in line with national standards;lactic acid content1830 mg/L,ethyl acetate content 18.24 mg/L,isoamyl acetate content 0.58 mg/L,ethyl lactate content 31.02 mg/L;the diacetyl and other physical and chemical indicators meet the national standard requirements,the body of the sour beer is amber,white and delicate foam,rich fruit flavor,high carbonation,mellow taste,outstanding ester flavor,rich taste,balanced acidity,is a rare sour beer.