| Kyoho grape is a kind of berry fruit which is rich with nutrition.The skin of grape is thin and juicy,which is easy to damage and thresh and the inherent physiological characteristics of grape is not conducive to its storage.At the same time,the grape industry is one of the main agricultural industries in Yingkou City.At present,there are outstanding problems such as irrational grape variety structure,low mechanization level,imperfect marketing system and low deep processing rate.In this paper,Kyoho grapes,Nanguo pears and Hanfu apples,which were abundant in Gaizhou Yingkou,were used as test materials,using two different fermentation modes:mixed fermentation and spontaneous fermentation,to study the best process path.Compare the sensory indexes,nutritional indexes,and antioxidant indexes of the two Jiaosu products during and after fermentation to get the best Jiaosu product production mode.Explore the changes of total phenols and total flavonoids in the vitro gastrointestinal digestion simulation of the two Jiaosu products under different digestion conditions to investigate the bioavailability of the active ingredients of the two Jiaosu products in the entire gastrointestinal tract.Based on mathematical modeling ideas,the quality changes of the two Jiaosu products under different storage conditions were studied,and a shelf life kinetic model was constructed.The results are as follows:Three kinds of fruits including Kyoho grape,Nanguo pear and Hanfu apple were used as the main raw materials to make compound juice.Through single-factor experiments and orthogonal optimization,with sensory quality as the main criterion and polyphenol content as supplementary standard,the optimal process for the final compound juice was determined to be 34%for grape juice and 16%for pear juice.The added amount of apple juice was 16%.Under these conditions,the obtained composite juice had the highest sensory score,92.0±2.0 points,and the polyphenol content was 25.46±0.09?g/m L.The compound juice was used as raw material,respectively connected to bifidobacterium lactis and lactobacillus casei for fermentation,and the total acid content was used as the response value.Through the Box-Behnken test,the optimal Jiaosu product process was determined as:Bifidobacterium lactis KJ 598784:cheese milk Bacillus BMBL 0624=1:1,the inoculum was 4.219%,the fermentation temperature was 44.314 h,the fermentation temperature was 34.074?,and the total acid content reached the most.Considering the cost and practicality,the fermentation parameters were adjusted:the amount of bacteria added was 4%,the fermentation time was 44 h,and the fermentation temperature was 34?.Through fuzzy mathematics combined with orthogonal test analysis,it was concluded that the best blending process was 6%of white sugar,2%of honey,and 0.04%of citric acid.During the fermentation process,the color depth and a value of the two Jiaosu products were increasing,and the hue and L value were decreasing.In addition,the p H value of the two Jiaosu products was continuously decreasing,and the total acid content was increasing.After the fermentation process,the two Jiaosu products had strong scavenging ability to DPPH free radicals,hydroxyl ion free radicals and ABTS~+free radicals,and the anti-oxidant activity of the mixedly fermented Jiaosu product was better than that of the spontaneously fermented Jiaosu product.In the state without meal,through the in vitro gastrointestinal digestion process,the total phenols and total flavonoids of the mixedly fermented Jiaosu products and spontaneously fermented Jiaosu products showed the simulated gastric digestion group>acid control group>blank control group,while the simulated intestinal digestion group>blank control group,and the content of total phenol and total flavonoids of mixed ferment was greater than spontaneous ferment.In the acidic environment of gastric digestion,not only did the total phenols not be released,but their content also showed a downward trend,but with the addition of pepsin,the total phenols were released in large quantities.At the same time,the acidic environment of gastric digestion promoted the release of flavonoids in the two Jiaosu products,while the neutral environment of intestinal digestion had no significant effect on the release of flavonoids.In the state with meal,through the in vitro gastrointestinal digestion process,the contents of total phenols and total flavonoids of the two Jiaosu products were higher than the state without meal.At the same time,compared with the state without meal,the state with meal did not affect the release of total phenols and flavonoids by the two Jiaosu products after simulated gastrointestinal digestion in vitro.At different storage temperatures,the mixedly fermented Jiaosu product was superior to spontaneously fermented Jiaosu product in sensory and nutritional indicators,and both Jiaosu products meet commercial sterility standards in terms of microbial indicators.The sensory quality,p H,color difference and total phenol content of the Jiaosu products were in line with the changes of the first-order reaction kinetic model,combined with the Arrhenius equation,and the weight fuzzy method was used to establish the shelf life of the product's corresponding quality parameters.The weighted correlation between the prediction model and the comprehensive quality evaluation=sensory score×30%+p H value×25%+color difference×30%+total phenol content×15%. |
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