Research On The Production Process Of Composite Fermenting Agent And Improving The Quality Of Steamed Bread

There is more a half of the population whose main food is wheat products in China,a great nation consuming wheat products.Besides,the steamed bread has been popular food for its advantages of fantastic taste and convenient portability.The traditional sourdough steamed bread compared with the yeast steamed bread exists problems of longer fermented time and unstable quality.Nevertheless,the latter has also its disadvantages of single smell,thin flavor and low nutrition value.Based on pervious studies,sensual and nutritional quality of the steamed bread with compound ferment agent contained yeasts and lactobacillus is evaluated to supply gaps of the traditional ferment agent in this study.The mixed culture consisting of Saccharomyces cerevisiae(N),Lactobacillus paracasei(G),Lactobacillus acidophilus(S)and Hanseula anomala(H)is researched by adjusting the inoculating proportion and culture condition.After mixed culture,the proportion of four strains approaches to the aim proportion(N:G:S:H=4:2:6:1).In conclusion,the condition of mixed culture is ascertained as follows:The inoculating proportion of four strains:N:1×106cfu/mL;G:2.5×106cfu/m L;S:1.6×107 cfu/mL;H:5x 105cfu/mL).N of 1%is firstly inoculated in the liquid medium of MRS with pH 6.0,and cultured 10 hours at 25 ? and 150r/min in the oscillator.In addition,S,G and H are secondly inoculated and cultured 4 hours at 35? and still.Then continue to culture 11 hours at 25 ? and 150r/min in the oscillator.In the article,comparison of the quality of steamed bread with compound ferment agent with the quality of steamed bread with sole yeast is described by five aspects:texture analysis,amino acid analysis,flavor substance analysis,shade and specific volume measurement.As a result,two ferment agents do not have evident difference in shade and specific volume aspects.In texture analysis,except difference of adhesiveness is significant(p<0.05),remaining indexes are not significant(p>0.05).In amino acid analysis,compared to total mount of essential amino acid,total mount of semi-essential amino acid,total mount of fresh taste amino acid and total mount of amino acid of the steamed bread with sole yeast,ones of the steamed bread with mixed ferment agent are enhanced 8.6%,9.8%,7%,and 7%,respectively.In flavor substance analysis,36 compounds are detected in the steamed bread with compound ferment agent,whereas,only 16 compounds in the steamed bread with sole yeast.The detected compounds contain mainly hydrocarbons,alcohols,esters and carbonyl compounds etc.This study is unprecedented to analyze the steamed breads with compound ferment agent and with sole yeast in the texture,flavor and nutrition composition,completely.It provides important theoretical reference for mechanism research and appliance of compound ferment agent.