Development Of Yak Sour Meat Starter And Its Influence On The Quality Of Yak Sour Meat

Yak sour meat is a kind of yak meat product developed according to the traditional sour meat fermentation technology in Sichuan and Chongqing areas.At present,it is produced and sold in Ganzi Prefecture and Aba Prefecture of Sichuan Province,But the processing technolo gy of yak sour meat is natural fermentation.Due to the influence of seasonal climate,artificial operating conditions,raw material characteristics and so on,the quality of yak sour meat is u nstable,and it limits the large-scale production of yak sour meat.Therefore,it is of great pra ctical significance to develop a direct input starter suitable for fermented yak sour meat.The main contents and results of this paper are as follows:(1)Screening of bacteria for yak sour meat fermentation.According to acid-producing ab ility and ester-producing ability,48 strains of lactic acid bacteria and 21 strains of aroma-prod ucing yeasts were obtained from 15 samples of Dong sour meat.Through the fermentation ch aracteristic test,safety test,biological characteristic test and compound test,M1 and Y26 were selected for the preparation of fermented yak sour meat starter.M1 has strong acid production ability,and the p H of fermentation broth can be reduced to 3.85±0.02 after 24 hours of ferme ntation.Y26 has strong ester production ability,and the total ester content after fermentation i n soybean juice medium is 4.21±0.17 g/L.Two strains can tolerate nitrite of 6%Na Cl and 150mg/kg,meet the safety standards,and can tolerate acid and spices.There is no antagonism bet ween strains.According to the identification of morphology,physiology,biochemistry and mo lecular biology,it is determined that M1 is Lactiplantibacillus plantarum strain and Y26 is Wi ckhamomyces anomalus strain.(2)The formula and fermentation parameters of M1 and Y26 compound starter for ferm enting yak sour meat.Through single factor and orthogonal experiments,the best formula of f ermented yak sour meat was determined as follows:fried highland barley powder 40%,dried chili noodle 7.5%,granulated sugar 5%,salt 4%,minced ginger 2.5%,prickly ash powder 2%,compound starter 1%(1×10~7CFU/g,strain ratio was lactic acid bacteria:yeast=1:2).T he optimal fermentation parameters are as follows:fermentation time 42 h,fermentation temp erature 25℃。(3)Effect of compound starter on the quality of yak sour meat.Using compound starter t o ferment yak sour meat,determining the microbial,physicochemical,color,texture and volat ile components in the fermentation process,and the effect of inoculation of compound starter on the quality of yak sour meat was comprehensively determined.The results showed that co mpared with traditional fermentation,no coliform bacteria were detected in yak sour meat in c ompound fermentation group after fermentation for 42 hours.The decrease rate of p H and wat er content of yak sour meat fermented by compound starter was significantly higher than that of traditional fermentation.The ammonia nitrogen(0.20±0.01)、a*(6.37±0.56)、e(3.24±0.31)and elasticity(0.728±0.04)of yak sour meat fermented with compound starter for 42 h were significantly higher than those of traditional fermentation for 48 h(0.16±0.01、4.92±0.69、2.12±0.37、0.655±0.06,p<0.05);the contents of volatile base nitrogen and nitrite we re significantly lower than those in traditional fermentation(p<0.01).In addition,a total of 102 flavor substances were detected after traditional fermentation and 115 flavor substances we re detected in yak sour meat fermented by compound starter.The types and contents of aldehy des,alcohols and esters fermented by compound starter are higher than those fermented by tra ditional fermentation.The comprehensive results showed that the compound starter could imp rove the quality of yak sour meat.