Analysis Of Microbiota And Flavor Of Kaili Red Sour Soup And Its Quality Improvement And Application

Red sour soup is a traditional spontaneously fermented food with a thousand years of history in Southeast Guizhou.It is made from tomato and red pepper as the main raw materials,supplemented by glutinous rice flour,ginger,garlic,white wine and other fermentation.The current production method is dominated by traditional natural fermentation,the microbial strains are messy and unstable,easy to be polluted by the environment,the fermentation cycle is long,the quality difference is large,and the application range is narrow;it is not conducive to standardization and industrialization.In this paper,through the in-depth analysis of the microbial diversity and flavor characteristics of sour soup,excellent strains are screened for inoculation fermentation,the fermentation process and formula are optimized,and the flavor quality is improved.On this basis,a convenient sour soup beef is prepared to expand the application range of red acid.It provides a theoretical basis for its industrial production and large-scale application.The main research results of this paper are as follows:(1)Illumina Mi Seq sequencing technology was used to analyze the microbial community of Guizhou sour soup,and the results showed that the absolute dominant genus of bacteria was Lactobacillus;the dominant fungal genus of red sour soup was mainly Pichia,Candida and Kazachstania;white sour soup is mainly composed of Debaryomyces and unclassified.At the same time,133 compounds were detected by headspace solid-phase microextraction combined with gas chromatography-mass spectrometry(HS-SPME-GC/MS),and esters and alcohols accounted for the largest proportion.Principal component analysis(PCA)shows that the characteristic compounds of red sour soup are mainly esters,hydrocarbons and alcohols;white sour soup is mainly composed of nitriles,acids,aldehydes and ketones.Partial least squares regression analysis method was used to analyze the correlation between microbiota and flavor substances.The results showed that 9 bacterial genera and 8fungal groups had a good correlation with flavor;in addition,excessive Lactobacillus could inhibit the formation of some flavor compounds.(2)Select the laboratory self-screened strain Lactobacillus plantarum NR1-7,Bifidobacterium animalis BZ11 and commercial Candida RY(number: CICC31494)to ferment the red sour soup.Taking total acid,soluble solids,amino acid nitrogen and sensory as indicators,the optimum formula of red sour soup was optimized by uniform design as follows: ginger 8%,garlic 4%,salt 2%,glutinous rice 2%,red rice2.5%.On the basis of single factor experiment,the optimal fermentation conditions were determined by response surface methodology(RSM)with total acid and sensory response values as follows: fermentation time 5 d,fermentation temperature 28 ?,inoculation amount 3%,strain ratio 1:1:1.(3)The physicochemical and nutritional indexes of the optimized red sour soup in the fermentation process were detected.The results showed that compared with spontaneous fermentation,the acid production rate of mixed bacteria fermentation was faster,and the lactic acid output reached about 3 times that of spontaneous fermentation;at the same time;The nitrite content is much lower than natural fermentation,which improves the safety of sour soup.The analysis of aroma components showed that the main flavor compounds of red sour soup were olefins,esters,and alcohols;among them,the relative content of esters and alcohols in the inoculated group was higher than that in the uninoculated group;at the same time,the activity of lycopene,capsaicin and 6-gingerol could be well maintained by inoculation fermentation.(4)The single factor and orthogonal experiments on the technology and formula of sour soup beef showed that the amount of salt,zanthoxylum bungeanum,soy sauce,glucose and litsea cubeba oil were 1%,0.06%,1.5%,0.6% and 0.6%,respectively.The results showed that the cooking time was 3 min,the thickness of meat was 2 cm,and the percentage of liquid meat was 40%.The beef in sour soup has better sensory and finished products.The physicochemical quality and flavor of the optimized product were analyzed.The results showed that the sour soup beef was superior to the control group in sensory,texture and color.87 volatile compounds were identified in the sour soup beef and 74 compounds in the control group.The addition of sour soup promoted the accumulation of unsaturated olefins,sulfides and ketones.