Effects Of Winter Bamboo Shoots And Tofu Curd On Volatile Components Of Stinky Tofu Brine

South stinky tofu is a kind of local characteristic flavor food.Brine gives stinky tofu unique flavor and is an important carrier.Traditional brine is usually made of tofu curd,winter bamboo shoot,amaranth,soybean sauce,Lentinus edodes and other raw materials mixed at random and fermented naturally for a long time.It is not clear the role of each ingredient,which is not convenient for standardization control and product quality stability.On the basis of pre-experiment,this paper studied the effect of different proportion of winter bamboo shoots and tofu flowers on the flavor of stinky tofu brine.On the basis of optimizing the quantitative analysis conditions,the volatile components,absolute quantitative conditions and odor activity of seven different proportion of winter bamboo shoots tofu brine were determined within 90 days under the condition of constant temperature fermentation at 30 ℃.Volatile components,absolute quantitative conditions,odor activity value(OAV)was analyzed,and the proportion range of winter bamboo shoots and tofu curd suitable for fermentation of stinky tofu brine was obtained.Two optimum ratios were selected for the determination of amino acid nitrogen,pH value and titratable acid.The specific results were as follows:1.Quantitative analysis conditions are optimized: In order to determine stinky tofu brine by solid-phase microextraction combined with gas chromatography-mass spectrometry,due to the different fermentation degree,there are problems such as supersaturation of detector,peak rushing of sample,calculation of relative content and absolute content,etc.It is necessary to determine the appropriate dilution factor.The study found that the dilution ranges of standard products are 10 times.The recovery rate should be more than 90%.2.Choose volatile substances which contribute more to the flavor of stinky tofu brine: phenol,4-methylphenol,indole and 3-methylindole.Through the determination of volatile components in brine fermentation with different proportion of bamboo shoots and beans,it can be found that the proportion of bamboo shoots and beans is different,and the volatile components vary greatly.5 phenols and 0 indoles were detected in brine with bamboo shoots and beans adding ratio of 1:0;6 phenols and 2 indoles were detected in brine with bamboo shoots and beans adding ratio of 0:1;6 phenols and 2 indoles were detected in brine with bamboo shoots and beans adding ratio of 1:1.There are 5 phenols and 2 indoles in the brine with the ratio of 1:4 bamboo shoots to beans,3 phenols and 2 indoles in the brine with the ratio of 4:1 bamboo shoots to beans,7 phenols and 2 indoles in the brine with the ratio of 2:3 bamboo shoots to beans,6 phenols and 1 indoles in the brine with the ratio of 3:2 bamboo shoots to beans.Thioether compounds were detected in bamboo shoots at the ratio of 1:4 and 2:3.3.OAV value analysis and comparison of main flavor components: According to the threshold calculation results of reference compounds in water,phenols,thioethers and indoles all have high OAV values because of their high content and low threshold value.Phenols with phenolic fragrance can make brine more mild.The OAV value of phenolic substances in winter bamboo shoots is more than 500 when the proportion of phenolic substances is more than 50%.The OAV value of sulfides and indoles in brine with the proportion of tofu flower more than 50% is more than 1000,which can contribute to the flavor of brine.Therefore,the addition of winter bamboo shoots and tofu flowers in brine ranged from 20% to 40% and 60% to 80% respectively,which contributed to the formation of brine flavor.4.By comparing tofu flower and winter bamboo shoot fermented separately,the optimum ratio of amino acid nitrogen and titratable acid in brine fermentation process was determined.It can be seen that the ratio of amino acid nitrogen and pH value of brine sample with winter bamboo shoot tofu flower added 1:4 was higher than that of brine sample with winter bamboo shoot tofu flower added 2:3.The titratable acid content of brine samples with the ratio of 2:3 was higher than that of brine samples with the ratio of 1:4.It was found that the proportion of amino acid nitrogen decreased after 60 days of constant temperature fermentation,which may be due to the consumption of nutrients and the need to supplement nutrients in order to maintain brine activity.