Study On Probiotic Fermented Cereal Beverage

With the fermentation of the national economy and the improvement of people’s living standards,pursuit of food has gradually improved.“Five grain health preservation”has been circulated for a long time in China,the profit made from cereals is in line with the pursuit of safety,health,convenience and fashion.Cereal fermentation can improve food flavor,increase digestion efficiency and richer nutrition.Fermented products of probiotics such as lactic acid bacteria can regulate intestinal bacteria and improve the efficacy of food.Therefore,this study innovates and integrates food processing high-tech pretreatment technology,modern enzyme technology,modern fermentation engineering technology and modern analysis and detection technology to develops rice,millet,and corn compound probiotic fermented beverages.The main findings are as follows:（1）Research on raw material pretreatment technology.Using Lactobacillus plantarum as the fermentation strain,the effects of different pre-treatment methods such as high temperature making,extruded expansion,cooking slaking on the sensory quality of the product and the number of viable bacteria are studied.The results show that extruded expansion is the best pretreatment technology for rice,millet,and corn;extruded expansion at a screw speed of 320 r/min and a temperature of 170°C is beneficial to the increase in the number of viable bacteria and sensory quality of the three raw materials,and is significantly different from other treatments（P<0.05）.When the ratio of rice,millet,and corn is 1:1:4,the sensory evaluation score is high,and the number of viable bacteria is 6.60±0.10 lg（cfu/m L）.The material-liquid ratio 1:8 and the material-liquid ratio 1:9 had no significant difference in sensory evaluation and viable bacteria count（P>0.05）,but it was significantly higher than the other material-liquid ratios（P<0.05）.The most suitable homogenization strip is:the homogenization pressure is 30 Mpa,and the homogenization time is 8min.Under this condition,the product sensory score and the number of viable bacteria are the highest.（2）Research on fermentation technology.Taking the number of viable bacteria and the sensory score of the product as indicators,studies have confirmed that Lactobacillus acidophilus,Lactobacillus plantarum and Lactobacillus casei are suitable for the fermentation of beverages with a ratio of 1:1:4 of rice,millet,and corn.Through fermentation performance test,single factor experiment and response surface optimization,the best fermentation process of cereal beverage was determined:fermentation temperature is 32℃,fermentation time is15.70h,and inoculation amount is 6.30%.The number of viable bacteria from cereal beverage reached 7.69 lg（cfu/m L）,and the sensory score was 85.28.The constructed cereal beverage fermentation regression model can be used to predict the actual situation of rice juice fermentation.（3）Analysis of fermented cereal beverage ingredients.The analysis of basic physical and chemical indicators showed that fermentation can increase the acidity of cereal beverage,and the sensory score increased significantly（up to 85.28±0.99）.Protein,total sugars,and reducing sugars decreased drastically,all by more than 50%;fat,calcium,zinc,magnesium,and iron all decreased;the results of amino acid analysis showed that the change of the total amount of amino acids before and after the fermentation of cereal beverage was not significant（P>0.05）,Isoleucine and leucine can be used by the strains,and fermentation can not increase the content of amino acids such as aspartic acid,glutamic acid,alanine,cysteine,histidine,etc.,while the change of other 11 kinds of amino acids is not significant（P>0.05）.The mixed fermentation of the three bacteria in a ratio of 1:1:1 can significantly increase the antioxidant capacity of cereal beverage,and the IC₅₀ of its DPPH scavenging ability,ABTS scavenging ability,hydroxyl radical scavenging ability,and superoxide anion free radical scavenging ability have been increased respectively 34.33,32.82,15.50,33.56%.（4）Research on the preparation and stability of fermented cereal beverage.Through studying the influence of different sweeteners,stabilizers,flavors and sodium chloride content on the sensory evaluation of fermented cereal beverage,single factor experiment,orthogonal experiment,the best level of cereal beverage blending technology is determined:the amount of xylitol added is 1%,the addition of white sugar is 2.5%,the addition of xanthan gum is0.1%,the addition of fresh corn flavor is 0.11%,and the sensory score is 96.