Isolation And Screening Of Kvass Mixed Fermentation Strains And Product Development

In recent years,with the rapid development of the beverage industry and the increasing improvement of people's living standards,people's requirements for beverages have gradually shifted to having reasonable nutrition and health care functions,and in the production process as far as possible without or less use of food additives,So fermented drinks with good sensory flavor are the best choice.kvass is a traditional fermented beverage in Russia.It is made from toasted bread crumbs or barley as raw materials,added with honey,and fermented by a variety of complex strains such as yeast and lactic acid bacteria.Its color is golden brown,sour and sweet taste,alcohol level is not higher than 1%,both refreshing drink and wine mellow,with appetizing spleen,appetite and cooling effect.At the end of the 19th century,kvass was introduced into China,and the production technology was mature in Xinjiang.The taste of kvass is close to that of traditional European style.However,due to the lack of research on complex fermentation bacteria and fermentation process standardization,large-scale production has not been formed,and most of the current production are still family-based production.Therefore,this research aims to screen and obtain the compound fermentation strains of Xinjiang traditional kvass,and optimize the fermentation production process.In this paper,through the isolation and screening of Xinjiang kvass compound strains,the optimal combination of fermentation strains was determined through sensory evaluation,and through one factor experiment(included wort concentration,inoculation amount,strains ratio,fermentation time and fermentation temperature),Plakett-Burman design,and response surface design combined with alcohol content,total acid and sensory evaluation to optimize the fermentation conditions.The physical and chemical indexes(including alcohol content,p H,soluble solids,number of lactic acid bacteria and yeast)and sensory indexes(including aroma composition and color)of the final product were determined and the antioxidant capacity of the product was compared with that of the commercial kvass products.Results are as follows:(1)Yeast,lactic acid bacteria and acetic acid bacteria were screened out from Xinjiang kvass and determined the best combination is MK_3-8L.casei 4787,YK_2-4 S.cerevisiae BL5 and6a Acetobacter pasteurianus strain Ap64.(2)Through single factor experiment,PB design and response surface design,combine the effects of total acidity and alcohol on sensory evaluation.We got the optimized fermentation parameter as follows:the wort concentration is 6°Bx,the vaccination is 8%,yeast:lactobacillus:acetobacter=2:2:1,fermentation period is 24.6 h,the fermentation temperature is 30?.(3)Through the comparison of the physical and chemical indexes and sensory indexes of homemade kvass and the commercial kvass products,the results are as follows:the soluble solids and alcohol content of kvass are higher than those of commercial products,and there are many kinds of aroma components,and it has a unique flavor and strong sweet and sour,so it has a high sensory evaluation score.(4)In this study,the antioxidant capacity of kvass was measured and compared with that of commercial products.The results showed that the second-fermentation kvass had strong antioxidant capacity.