Effects Of Microbial Separation And Intensive Fermentation On Soy Sauce Quality In Soy Sauce Brewing Function

Soy sauce is the main seasoning in Asian countries such as China,Japan,and South Korea,and it is becoming more and more popular in Western countries and has become indispensable condiments in people’s diets.Soy sauce is mainly made of soybeans and wheat as raw materials,through the fermentation of mold,yeast and bacteria multi-microbial communities,the microbial communities involved in the soy sauce fermentation process are very complex,and it is very difficult to control the fermentation process,and the functional microflora in the soy sauce brewing environment is the key factor affecting the flavor quality of soy sauce.In recent years,with the advancement of biotechnology,the use of enhanced functional microorganisms to improve the flavor quality of soy sauce has become a hot spot.In this study,we started from the separation of functional microorganisms in the fermentation process of Japanese-style high-salt dilute sauce mash,systematically studied its fermentation functional characteristics and environmental adaptability,strengthened functional microorganisms in Japanese-style and Cantonese high-salt dilute fermented soy sauce,and clarified the correlation between functional microorganisms and main flavor substances in the brewing process of soy sauce.The main findings are as follows:(1)Using traditional microbial separation technology,eight strains with good salt tolerance were isolated from Japanese-style high-salt dilute fermented sauce mash,and after strain morphological observation and strain function determination,strains JLY60-1 and JLB30-2 that can synthesize 4-vinyl guaiacol and 4-ethyl guaiacol with ferulic acid were screened and identified as Wickerhamiella versatilis and Bacillus subtilis.The results showed that the optimal growth temperature of W.versatilis JLY60-1 was 30°C,which was the same as the fermentation temperature of Japanese-style high-salt dilute soy sauce,and FA could be converted to generate 4-VG and 4-EG in a high-salt environment,and the concentration of4-VG in the fermentation broth reached 7.90 mg/L and the concentration of 4-EG reached12.82 mg/L in the fermentation culture medium at 20% salt concentration for 15 days at 30°C and 150 rpm.The optimal growth temperature of B.subtilis JLB30-2 is 45°C,which is the same as the fermentation temperature of Cantonese high-salt dilute soy sauce,and this strain also has the ability to transform FA to generate 4-VG and 4-EG in a high-salt environment,and the concentration of 4-VG in the fermentation broth reached 34.2 mg/L and the concentration of 4-EG reached 21 mg/L in a fermentation medium with a salt concentration of20% salt concentration at 45°C and 200 rpm for 15 days.(2)The progressive change of the main functional components in the brewing process of Japanese high-salt dilute soy sauce and Cantonese high-salt dilute soy sauce was analyzed by high performance liquid chromatography,and the sensory evaluation of the two process products was carried out,and it was found that the sourness and sweetness of Cantonese soy sauce were higher than that of Japanese-style soy sauce,and the umami and comprehensive taste were lower than that of Japanese-style soy sauce.(3)In the process of aseptic fermentation of high-salt dilute soy sauce,the fermentation broth of functional strains was inoculated and fortified into soy sauce and co-fermented with Aspergillus oryzae,and the soy sauce of unfortified functional strains was used as a control to analyze and study the effect on the formation of main flavor substances of soy sauce during fermentation.The results showed that in the process of Japanese-style high-salt dilute soy sauce,the fortified strain W.versatilis fermented at 30℃ for 30 days,the contents of 4-VG and 4-EG in the soy sauce fermentation broth were 16.5mg/L and 30.5mg/L,respectively,and the control group was 1.83mg/L and 3.03mg/L,respectively,which increased by 8 times and 9times,respectively,and the content of aldehydes and ketone volatile flavor substances in soy sauce also increased,indicating that strain W.versatilis can significantly increase the content of 4-VG、 4-EG、 aldehydes and ketones volatile flavor substances in soy sauce,and increase the characteristic aroma components of soy sauce such as floral and fruity aroma,caramel aroma and mellow aroma.In the brewing process of Cantonese high-salt dilute soy sauce,the content of 4-VG、 4-EG in the fermentation broth was 13.5mg/L and 29.75 mg/L and that in the control group was 2.5 mg/L and 4.85 mg/L.The amino acid content in the experimental group was 55.7 g/100 g,and the control group was 43.5 g/100 g,and the amino acid content also increased significantly.The volatile flavor substances in soy sauce was richer,indicating that strain JLB30-2 could well adapt to the high salt,high temperature and low oxygen environment of Cantonese soy sauce brewing.(4)The two strains of functional microbial yeast JLY60-1 and Bacillus subtilis JLB30-2screened in this study can be well adapted to the Japanese high-salt dilute soy sauce brewing process environment,and the latter can be well adapted to the Cantonese high-salt dilute soy sauce brewing process environment,and both can efficiently synthesize 4-VG and 4-EG,which significantly improve the flavor content of the product,laying a foundation for further improving the quality of soy sauce,and has a good promotion and application prospect.