| High hydrostatic sterilization is an emerging cold sterilization technology.Compared with traditional thermal sterilization,it has the advantages of high efficiency and time saving,and retains the flavor of the product.Nowadays,the quality of food nutrition is of great concern.Efficiently killing the juice microorganisms and prolonging the storage period of the product,while retaining the product’s nutrients as much as possible has become a research focus in the field of fruit and vegetable processing.This article discusses and comparatively studies the effects of fresh juice during cold storage at 4 ℃,conventional heat treatment and high hydrostatic pressure treatment on the blueberry juice microorganisms,color,and nutritional quality parameters(monomer anthocyanin,total anthocyanin,total phenol and antioxidant activity),revealing the key factors for the change of monomer anthocyanins of blueberry juice during refrigeration,determines the optimal conditions for the industrial production of blueberry juice.According to the color measurement results,it was found that the high hydrostatic pressure treatment can better maintain the color of blueberry juice.There was no significant difference between the color of the juice in the high hydrostatic pressure treatment group and the control group on the processing day,and there was a significant difference between the heat treatment group and the high hydrostatic pressure treatment group(P <0.05),the color difference of fruit juice is not significant under different high hydrostatic pressure treatment conditions;80 ℃,10 min heat treatment has a great influence on the color of blueberry juice,Juice color darkens significantly,which greatly reduces the consumer ’s preference for fruit juice.The difference in color of juices between 10 and 20 days of cold storage was similar to that of day 0;there was no significant difference in color of blueberry juice between 30 days of cold storage under different processing conditions.According to the measurement results of the blueberry juice microbial indicators,the total number of juice colonies and mold yeasts under different processing and refrigeration conditions are less than 102 CFU / m L,which meets the requirements of the total number of colonies in beverages in China ’s national food safety standard GB 7101-2015.Can be recommended for commercial sterilization conditions.However,combined with the measurement results of the total anthocyanins,total phenols and total antioxidant capacity of the juice,it was found that all the high hydrostatic pressure treatment conditions and the heat treatment conditions of 70 ℃ and 10 min had little effect on the anthocyanins and total phenols of blueberry juice,80 ℃ or higher The temperature results in severe loss of anthocyanins and polyphenols.Combined with the measurement results of total antioxidant capacity,it is found that the change trend of total antioxidant capacity under different processing and refrigeration conditions is similar to that of total anthocyanins and total phenols.70 ℃,10 min heat treatment and 400 ~ 600 MPa 5 ~ 10 min high hydrostatic pressure treatment has a certain protective effect on the antioxidant capacity of blueberry juice,but 80 ℃,10 min heat treatment conditions can not well maintain the antioxidant capacity of blueberry juice.In addition,this experiment identified a total of 10 monomeric anthocyanins in blueberry juice by high-performance liquid chromatography-mass spectrometry,and identified the top three monomeric anthocyanins in blueberry juice as mallow malvidin-3-O-galactoside,mallow malvidin-3-O-arabinoside and mallow malvidin-3-O-glucoside.The stability of mallow pigment during cold storage is much higher than that of other anthocyanins,because the number of methoxy groups at the 3 and 5 carbon positions of the anthocyanin parent phenolic ring is higher than that of other anthocyanins.According to this principle,10 kinds of colors will be found The glycosides are sorted according to the stability of the nucleus,and the results are as follows: delphinidin = cyanidin < petunidin < peonidin < malvidin.Through the experimental results,it was found that high hydrostatic pressure and heat-treated juices delphinidin-3-Oglucoside,cyanidin-3-O-galactoside,petunidin-3-O-galactoside,cyanidin-3-O-arabinoside,peonidin-3-O-arabinoside 5 anthocyanins are less stable,while malvidin-3-O-arabinoside,malvidin-3-O-galactoside,malvidin-3-O-glucoside,malvidin-3-O-acetylgalactoside and malvidin-3-O-acetylglucoside 5 anthocyanins are relatively stable.The anthocyanin stability results were consistent during processing and during refrigeration.In summary,all treatment conditions can be recommended as commercial sterilization conditions.Although there are significant differences in the stability of monomer anthocyanins during refrigeration,some conditions in high hydrostatic pressure and heat-treated blueberry juice show higher anthocyanins Content and antioxidant capacity.Combining with industrial energy saving perspective,high hydrostatic pressure of 400 MPa,5min treatment group and 70℃,10 min heat treatment group can be recommended as the optimal treatment conditions for blueberry juice processing. |
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