Effect Of Processing Technology On The Quality Of Loquat Juice

Loquat Loquat is native to China, rich in production. The fruit is soft, juicy and delicious, with a variety of nutrients and active substances. Loquat fruit is sensitive to mechanical damage and decomposition during storage after short harvesting time, causing resources and economic loss. Various processing of loquat fruit become a hot research topic and the juice with its soft texture and sweet taste is deeply loved by consumers. Scholars tend to use sensory score as evaluation index to optimize loquat fruit juice processing technology in exsisting report. While this dissertation aims to analyze the processing of loquat fruit juice systematicly by measuring nutrition index and physiological and biochemical index, and results will provide theoretical and technical reference to the manufacturing process of loquat or other fruit for the future by optimizing the loquat fruit juice processing technology. The conclusions are as follows(1)Color preserving immersion(20 % lemon juice and 1 % salt solution) showed the best color retention of three process mode. Choosing 20 to 25 s pulping time was ideal, an essential part of fruit juice process, comprehensive considering the clarity, colour and nutritional value of product. The loquat fruit juice enzyme hydrolysis parameters through comprehensive experiment analysis were as follows: 2 % pectinase 4 μl/g, enzymolysis time 3-4 h. By sensory score and orthogonal experiment analysis showed the optimization recipe parameters of loquat fruit juice was 40 % loquat fruit normal juice, 15 % sugar and10 % lemon juice.(2)Of fresh fruit and loquat products in different fruit juice processing steps(color protection, pulping, enzymolysis, filtration, blending), the color parameter of loquat products exhibited an initial increase and a final decrease, peaking at enzymolysis process. The contents of soluble solid and titratable acid decreased first and increased significantly after blending process while the contents of total phenolics, flavonoids and ABTS+· scavenging rate tended to reduce. The main volatile compounds were alcohols, aldehydes and ethers. Principal component analysis(PCA) showed the fresh fruit and products after color protecting and deploying were best in color, taste, aroma quality and antioxidant performance than the other three processing steps, which reduced the quality of products in different degree.(3)The content of vitamin C of loquat juice was lower when the temperature was high under the same conditionscompareing with the loquat fruit juice in light, the vitamin C content was higher in dark, which showed that loquat fruit juice is more suitable for being kept in darkness at low temperature. The vitamin C of loquat juice degradation dynamics analysis showed that the degradation rate(k) constant tend to increase with the increase of temperature. The value increases significantly during 5℃ to 50℃ and it became slowdown when the temperature was over 50℃.After the loquat juice was diposed in 5℃ water bath, the vitamin C degradation linear regression coefficient R2 in zero order reaction and the first order showed no significant difference. And the the regression coefficient of the first order reaction of Vitamin C in 30℃, 50℃ and 70℃ was significantly higher than that of zero order reaction which showed that loquat fruit juice vitamin C degradation kinetics model conformed to the first order kinetics reaction.The present study showed that manufacturing process exhibited strongly influence on color, taste and aroma of loquat products. Processing and storage of loquat juice need to be further studied.