Development Of Fermented Beverage With Lactic Acid Bacteria And Analysis Of Nutritional Components Before And After Fermentation

With the improvement of living standards,people pay more and more attention to diet health.On the basis of beverage processing technology,combined with modern microbial fermentation technology,cereal fermented beverage not only retains the nutrients of cereal itself,but also improves the nutritional value of cereal with the help of probiotics produced by microbial fermentation.At the same time,the active probiotics in beverage contribute to human intestinal health.Cereal fermented beverage provides a new research direction for cereal food development.Using millet and glutinous rice as main raw materials,L.paracasei L1 and L.casei YQ336 isolated from naturally fermented sweet potato sour milk and tofu sour milk as fermentation strains,the processing technology,nutrient changes before and after fermentation and stability during storage of Lactobacillus fermented cereal beverage were studied.1.Study on pretreatment process of raw materials.The number of living bacteria and sensory evaluation were used as indexes,the pretreatment conditions of raw materials were determined as follows:millet and glutinous rice were used as raw materials,the ratio of material to water was 1:50,the soaking time was 24h,and the medium beating time was 30 s.under these conditions,the sensory score and cell concentration of fermented beverage were the highest.2.Optimization of processing technology of fermented cereal beverage.The optimum processing conditions were determined by single factor and orthogonal experiments with total acidity and viable count as indexes:initial p H 7,fermentation time 24 h,fermentation temperature 35?,adding 0.1%Osmanthus fragrans and 0.2%Gardenia jasminoides Ellis,0.06%sodium alginate,0.06%xanthan gum and 0.15%CMC Na as mixed stabilizers,sterilization at 95?for15 min Under this condition,the sensory score and cell concentration of fermented beverage were the highest.3.Non targeted metabonomics technology was used to detect the changes of small molecular substances with molecular weight less than 1000 before and after fermentation.Non targeted metabonomics of liquid chromatography-mass spectrometry(LC-MS)combined with principal component analysis(PCA)and partial least squares(PLS)were used to analyze the differences between the fermented and pre fermented cereal beverages.Results a total of 145 kinds of 25different metabolites were detected in the fermented beverage,including 32 kinds of organic acids and derivatives,20 kinds of flavonoids,10 kinds of nucleotides and derivatives,9 kinds of amino acids and derivatives,7 kinds of sugars,etc1-hydroxy-2-naphthoic acid;dihydroresveratrol,a natural polyphenol compound,which can be used to treat acute pancreatitis and related lung injury;daidzein,Vitexin and genistein,which have antihypertensive,antitumor and antioxidant effects.Through the analysis of KEGG metabolic pathway,the results showed that there were 19 metabolic pathways with significant differences.4.Comparative analysis of nutritional components in the fermentation process of cereal beverage.The content changes of flavonoids,total phenols,organic acids and other substances in cereal beverages within 24 h of fermentation were determined by spectrophotometer and high-phase liquid chromatography.The results showed that the total acidity gradually increased,reaching a maximum of36~oT at the 24th hour of fermentation.The p H value decreased gradually and dropped to a minimum of 3.67 at the 24th hour of fermentation;the reducing sugar content increased first and then decreased,rose to a maximum of 57.66 mg/m L at the 12th hour of fermentation,and dropped to 51.67 mg/m L at 24 h of fermentation;the content of flavonoids It increased first and then decreased,reaching a maximum of 1.59 mg/L at the 12th h of fermentation,and dropping to1.42 mg/L at the 24th h of fermentation;the DPPH free radical scavenging rate increased to a maximum of 87.44%at the 18th h,and at the 24th h The time dropped to 75.34%;organic acid analysis showed that the content of lactic acid in the beverage was the highest,reaching 4.816 mg/m L at the end of fermentation;the number of viable bacteria was as high as 5.4×10~8cfu/m L.In general,the content of total acidity,lactic acid,total sugar,reducing sugar and flavonoids increased after fermentation.The content of flavonoids and the scavenging rate of oxygen free radical decreased after fermentation.DPPH radical scavenging rate was at a high level in the fermentation process.Other substances changed little.5.Quality standard and shelf life test of fermented cereal beverage.The protein content of the product was 2.2 mg/L,the carbohydrate content was 33.8g/L,the Na content was 0.66 g/L,the total solid content was 75 mg/L,and the number of lactic acid bacteria was 5.4×10~8cfu/m L.During 28 days storage,the number of bacteria was 6.9×10~7cfu/m L,the stratification rate was within 5.6%,the acidity was below 41~oT,and the p H value was 3.64.