Effects Of Processing Methods On The Quality Of Strawberry,Blueberry And Mulberry NFC Compound Juice

Strawberries,blueberries and mulberries are all berries,rich in anthocyanins and other nutrients,but because of the high moisture content of strawberries,blueberries and mulberries,they are susceptible to microbial contamination,and they are spoiled after storage for several days under natural conditions.The fruit is seriously wasted.Processing strawberry,blueberry and mulberry into composite juice not only solves their preservation problems,but also increases the added value of their products,which is of great significance for promoting the development of non-reduced concentrated juice(NFC)composite juice industry chain.The paper studied the effects of strawberry,blueberry and mulberry juice thawing technology,lactic acid bacteria fermentation technology,yeast acetic acid combined fermentation process and sterilization technology on juice quality,which provided a reference for the deep processing of compound juice.The main findings were as follows:(1)The effects of different thawing methods(microwave thawing,ultrasonic thawing,water bath thawing,natural thawing)on juice yield and fruit juice quality of strawberry,blueberry and mulberry were studied,and the best thawing methods of strawberry,blueberry and mulberry were determined.The results showed that compared with fresh strawberry juice,the microwave-thawed strawberry juice had the smallest difference in acidity,color,viscosity and water-soluble pectin content,and it was the treatment method with better anthocyanin content in the four thawing methods.Relevant physical and chemical indicators The change was significant(p<0.05);the pH,titratable acid and soluble solid content of microwave thawed blueberry juice were not significantly different from fresh blueberry juice,and the total anthocyanin content was the highest(62.45 mg/100g).The monomer anthocyanin was detected.The highest number(11 species),in addition,the total phenolic content(2.27 mg/g)and antioxidant capacity(46.88 ?moL/g)of blueberry juice after microwave thawing is the highest,the best preservation of nutrient content;ultrasonic thawed mulberry Juice pH,titratable acid and soluble solid content are the smallest difference from fresh mulberry juice,viscosity(0.11 mPa·s),water-soluble pectin(5.91 mg/g),total anthocyanin(266.17 mg/100g),cornflower Content and antioxidant capacity of inulin 3-O-glucoside(136.15 mg/100g),cyanidin 3-O-rutinoside(87.75 mg/100g),total phenol(2.86 mg/g)and ORAC(47.45 ?mol/g)were significant(p<0.05)better than other methods of thawing.(2)Study on the fermentation of lactic acid bacteria(Lactobacillus casei,Leuconostoc mesophila and Lactobacillus acidophilus)and the combined fermentation process of yeast and acetic acid bacteria in strawberry juice,blueberry juice and mulberry juice,found that three kinds of lactic acid bacteria could not be in strawberry Juice and blueberry juice grow well,could grow well in mulberry juice,and reach the maximum bacterial amount after fermentation for 16 h,and the sucrose in the mulberry juice fermented by the three bacteria was consumed,glucose,fructose,The content of malic acid,citric acid,cyanidin glucoside,cyanidin glucoside decreased,acetic acid and lactic acid content increased,and the total phenol content and color difference were not significant.Yeast and acetic acid bacteria combined fermentation of strawberry juice,blueberry juice and mulberry juice fermentation process,the results show the optimal time for yeast fermentation of strawberry juice was 24 h,and the optimal time for fermentation of strawberry juice by acetic acid bacteria was 60 h;the optimal time for fermenting blueberry juice was 120 h,the optimal time for fermentation of blueberry juice by acetic acid bacteria was 60 h;the optimum time for yeast fermentation of mulberry juice was 32 h,and the optimal time for fermentation of mulberry juice by acetic acid bacteria was 60 h.(3)It was preliminarily determined by sensory evaluation that the suitable ratio of strawberry blueberry mulberry compound juice was 1:1:2.Based on this compounding ratio,the effects of different sterilization methods and storage temperatures on the quality of the composite juice during storage were studied.Under the storage conditions of 4 °C and 25 °C,the effects of ultra-high pressure treatment(550 MPa,5 min)and heat treatment(95 °C,2 min)on the nutritional quality,color and antioxidant capacity of strawberry,blueberry,mulberry clear juice and turbid juice were compared.The results showed that the content of soluble solids,total phenolics,total anthocyanins and monomeric anthocyanins in the composite clear juice and turbid juice decreased significantly with the prolongation of storage time,and the chromatic aberration significantly increased(p<0.05),especially the decrease of the composite juice stored at 25 °C was much greater than that at 4 °C,indicated that the low temperature storage was beneficial to reduce the loss of nutrient quality of the juice;compared with the heat treatment,the change of the indicators of the ultra-high pressure treated compound turbid juice was smaller,indicated that the super High pressure could better maintain the nutrition and color of the turbid juice;composite clear juice was the change of the indexes of the heat treatment was smaller.