| In this paper,fresh leaves of the jiukeng species were manufactureed through the withering-rubbing-fermentation-drying process to obtain Maocha.After that,Maocha was processed to the superfine tea powder in Yurun Group Nanotechnology Engineering Center of Nanjing University.Maocha was ground by the HQM-10 fiber shear grinding miller for 20,60,and 300 minutes to obtain sample 1,sample 2 and sample 3,respectively.The grinding rod is made of stainless steel,the temperature of the grinding chamber is maintained below 40°C.After grinding for 300 minutes,Maocha was crushed for 3 min and 15 min with the HQB-300 flat-type jet mill to obtain sample 4 and sample 5,respectively.The temperature during grinding was set at 3~5°C.Through comparing the performance index of superfine powders with different particle sizes,the effects of superfine grinding on the physical characteristics,dissolution of chemical components and functional properties of Congou black tea were investigated The results showed that the superfine tea powder has better physical and functional properties than tea leaves.This paper provides a theoretical basis for the application of superfine grinding technology in the black tea processing industry.The black tea powders were crushed into an average particle sizes of 26.116,9.612,4.338,3.742 and 3.328?m,respectively,and the effects of Superfine grinding on the physicochemical properties of tea powder were investigated.The results show that with the decrease of particle size,the density,expansion force and water holding capacity of Superfine black tea become smaller,and the Angle of rest and sliding Angle increases gradually,and the tea powder becomes less liquid.The L value and b value of chroma gradually increase,indicating that the Superfine grinding has an enhancement effect on the color of black tea infusion.Results showed that as the superfine tea powder particle size reduced,the content of water,amino acid and soluble sugar in extract increased significantly,but the content of tea polyphenols,tea pigment,and crude fiber gradually reduce,the trend of which may be attributed to the reason that the superfine grinding destroyed the cell wall structure of tea,whose main body is cellulose.When the coarse fiber was damaged,the containing ingredients were more easily exposed.Moreover,tea polyphenols is not stable,and easy to be oxidized,so the content of tea polyphenols and tea pigments will has a reducing tendency.To investigate the hypolipidemic effect of tea powder,the rats in the experimental group were fed with superfine tea powder or instant tea powder,while the high-fat model rats and the normal rats were used as the control group.The effects of five Superfine tea powder samples on the total cholesterol,triglyceride,and high-density lipoprotein in the blood were observed.To investigatedthe effect of density lipoprotein levels,and hypoglycemic effect of tea power,the rats in the experimental group were fed with superfine tea powder or instant tea powder,while the diabetic model rats and the normal rats were used as the control group.Effects of blood glucose levels in hyperglycemic mice.The experimental rats were continuously fed with five samples of A,B,C,D,and E of Superfine tea powder for 2 weeks at a dose of 2g crude drug/Kg.The results showed that these five samples of Superfine tea powder significantly reduced the serum glycerol levels(TG),also significantly increased the levels of serum high-density lipoprotein(HDL-C),but had no effect on serum cholesterol(TC)levels and serum low-density lipoprotein(LDL-C)levels The hypoglycemic effect of alloxan-induced diabetic mouse model showed that none of the five superfine powders A,B,C,D,E had hypoglycemic effect.In this study,the effects of tea powder with different added dosages and different particle sizes on the sensory and color of ice cream were invstigated.The sensory evaluation results showed that the average particle size of superfine tea powder was D50 = 4.338?p.,with the adding dosage of 10%,obtaining the highest total score of sensory evaluation is that the ice cream made from this formula is uniform,the aroma of black tea is obvious,and the taste is soft.In the analysis of the correlation between color and color difference in sensory evaluation,the color score and the lightness of ice cream showed a negative correlation(P<0.05)with the correlation coefficient of-0.416,and was positively correlated with the a value(P<0.01)with the correlation coefficient of 0.518;there is a certain correlation with b value.The results shows that the lower the ice cream brightness,the more red the infusion and the higher the color score.The more reddish the color of the ice cream,the higher the color score in the sensory review and the more popular it is.The sensory evaluation color was used as the dependent variable,and L*,a*,and b* were independent variables.SPSS19.0 statistical analysis software was used to establish a multiple regression equation.Y=—13.797+0.295X1+1.636X2—0.097X3(Notes: Y is the color in the sensory review;X1 is the L* value in the color difference;X2 is the a* value in the color difference;X3 is the b* value in the color difference.)The correlation analysis of ice cream sensory indicators showed that:1.The solubility of the mouth is negatively correlated with the viscosity,and the correlation coefficient is-0.392;the mouth melting are extremely negatively correlated with the ice crystal sensation and firmness,and the correlation coefficients are respectively for-0.676,-0.572;mouth solubility was significant positive correlated with greasy degree,the correlation coefficient was 0.670.The results indicated that the ice cream ice crystals,the lower the firmness,the better the mouth melting;the higher the degree of creaminess,the better the mouth melting.2.There was a significant positive correlation between ice crystal sensation and firmness,and the correlation coefficient was 0.621.The correlation between ice crystal sensation and slickness was extremely negative and the correlation coefficient was-0.774,indicating that the lower the ice cream firmness,the higher the slickness andthe more ice crystals.Through the correlation analysis of ice cream texture indicators,it can be seen: 1.Hardness and uniformity showed a very significant positive correlation,the correlation coefficient was 0.652,indicating that the higher the ice cream uniformity,the higher the hardness.2.The homogeneity was negatively correlated with the viscosity,and the correlation coefficient was-0.717,indicating that the ice cream has higher viscosity and lower uniformity.Through the correlation between the sensory evaluation of ice cream of each index and the texture of the indicators,it can be seen: creaminess and ice cream hardness was significantly negative correlated with each other,the correlation coefficient was-0.479,indicating that the higher the ice cream hardness,slippery degree is lower.Combing the properties off physics,chemistry,function and its application in ice cream,the optimal formula of ice cream was obtained.The results also showed that superfine tea powder have a certain lipid-lowering function,but the particle size of superfine tea powder has no obvious effect on its function that lower blood fat and blood sugar. |
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