Establishment And Application Of Quality Evaluation Method And System For Vine Tea

Vine tea is a tea-like product made from the stems and leaves of Ampelopsis grossedentata.Vine tea is a resource for both medicine and food.,which is rich in dihydromyricetin and other flavonoids and has a variety of health effects.At present,the sensory evaluation indexes and methods of vine tea mainly draw lessons from the traditional tea standards,and there is no physiochemical quality evaluation standard,which can not well reflect the real quality of vine tea.At the same time,there are few studies on the quality improvement and innovative technology of vine tea.It is of positive and practical significance to research the establishment and application of the quality evaluation method and system of vine tea.In this paper,from the point of view of sensory flavor and physiochemical indexes,the sensory evaluation method and physiochemical quality evaluation model of vine tea were established by using mathematical analysis methods,to construct the quality evaluation system of vine tea,which was applied to the classification of vine tea products and the optimization of processing conditions of vine tea.At the same time,the correlation between the quality of vine tea and the physiochemical properties such as colloidal nanoparticles,Zeta potential,and precipitation characteristics of vine tea soup was discussed.The main results are as follows:(1)The sensory evaluation of 10 vine tea samples was carried out by the tea evaluation group,and the sensory intensity was taken as the evaluation index.27 sensory descriptions of vine tea,including 5 shapes,5 soup colors,7 aromas,and 10 flavors,can be used to evaluate the sensory quality of vine tea samples.Through further analysis,it is concluded that gum,fresh yellow,grass,wood,betel nut,flower,sweet,sweet,refreshing,throat prickling,rough sensation,and Shengjin are the main sensory attributes to distinguish the quality of vine tea.On this basis,the evaluation table of vine tea sensory quality index was established and the detailed rules of vine tea sensory score were obtained.finally,the sensory scoring method of vine tea was determined by the fuzzy mathematics method.that is,the fuzzy sensory score S is the product of the comprehensive score set Y and the comment set V.(2)Using single factor experiment and CCD experimental design,taking the ratio of tea to water,brewing temperature,brewing time,and brewing times as variables,and taking the fuzzy sensory score of vine tea as the evaluation index,the brewing conditions of vine tea soup were optimized,that is,brewing time 6.0min,brewing temperature 85.0 ?,water-tea ratio 50.00-1.Based on the above sensory scoring method and tea brewing method,the sensory evaluation method of vine tea was finally determined.(3)To construct the evaluation model of physiochemical quality of vine tea,15 related physiochemical quality indexes of vine tea were determined with 10 samples of vine tea as objects.Four core quality indexes of tea soup,flavonoids(A₁1),polyphenols(A₁2),soluble sugars(A₁3),and brightness(A₃),were determined by variation analysis,correlation analysis,and principal component analysis.After using the entropy method to determine the weight of the quality index,combined with grey correlation analysis,the evaluation model of physical and chemical quality of vine tea was established:(?)_i=(?)_A11×0.1811+(?)_A12×0.2242+(?)_A13×0.4154+(?)_A3×0.1793.It was proved that the fuzzy sensory score was fitted with a high degree of fit(R² = 0.8279).According to the score of the model,the vine tea samples can be divided into three grades: the first grade(1.00-0.80),the second grade(0.80-0.70),and the third grade(0.70-0.60).(4)the aroma components of 10 kinds of vine tea samples were determined by HS-SPME-GC-MS,and 45 kinds of aroma components,including n-nonanal and saffron aldehyde,were determined,Through the qualitative and semi-quantitative analysis of the aroma components of vine tea,it was preliminarily determined that the characteristic aroma of vine tea was n-nonanal,1-octene-3-ol,?-ionone,hexanal,benzaldehyde,and sukatone(6-methyl-5-heptene-2-one).(5)The optimization of technical conditions of vine tea processing was carried out.Taking the score(MS)of the physicochemical quality evaluation model of vine tea as the evaluation index,the processing procedures of tender leaf type vine tea and adult leaf type vine tea were optimized,and the process parameters of the green killing process and fermentation process were optimized.Adding the shaking process based on the traditional technology is beneficial to improve the quality of vine tea,and the optimum process conditions for tender leaf type vine tea are stir-frying temperature200? and time 20 min,and for adult leaf type vine tea,blanching temperature 100?and blanching time 2min are the optimum conditions.The fermentation strain of adult leaf type vine tea is optimized,and the addition of yeast + Rhizopus + Aspergillus Niger is beneficial to improve the physicochemical quality of vine tea.The optimized fermentation conditions are fermentation time 5h,fermentation temperature 32?,and the number of mixed bacteria 0.04%.Through the aroma verification experiment of vine tea,it was found that the aroma concentration and the types of aroma compounds of vine tea samples prepared under optimized conditions increased,and the aroma of vine tea was similar to that of lilac,accompanied by elegant fruit aroma.(6)Taking tea leaf type of tender and adult as research objects,from the point of view of original tea solution YT,colloid and true solution mixed system JZ and suspension precipitation XC,the changes of chemical composition,colloid particles,and precipitation of vine tea during soaking were studied,And the correlation between the quality of vine tea and the physicochemical and precipitation properties of colloidal particles was analyzed.To better determine the physicochemical properties of vine tea colloid nanoparticles,the optimum separation conditions were obtained as follows: the original tea solution was filtered by initial filtration,then centrifuged by 1500r/min and then filtered by 0.45?m filter membrane;the optimum heat preservation condition of tender leaf type solution was 35?;the best heat preservation condition of adult leaf type solution was 30 ?(the test temperature was the same as the heat preservation temperature).The dynamic changes of flavonoids,polyphenols,soluble sugars,and free amino acids in vine tea during soaking were positively correlated with the soaking time,and the increasing rate was mainly increased at first and then decreased.The physicochemical properties of tea colloid particles did not change obviously during the soaking process of tender leaf type and adult one.and the total precipitation also fluctuated.There was no significant correlation between the quality of tender leaf type vine tea and each index,but there was a significant correlation between the quality of adult leaf type vine tea and total light intensity,irreversible precipitation and Zeta potential.