不同采摘季节与加工工艺对茶叶品质及抗氧化能力的影响OA

[Objective]This study aimed to investigate the effects of different plucking seasons and processing tech-niques on tea quality and antioxidant capacity,clarify predominant components of summer-autumn tea,providing theo-retical basis for high-value development and utilization of summer-autumn tea.[Method]Teas made from the same variety(large-leaf tea plant,one bud and one leaf)in the Shaoguan area of different plucking seasons(spring,summer-autumn)and different processing techniques(green tea,yellow tea,and black tea)were taken as research materials.Indicators such as tea infusion color difference,water extracts,total flavonoids,soluble sugars,tea polyphenols,catechin compo-nents,and free amino acids were determined to evaluate antioxidant capacity of the teas.Multivariate statistical methods including principal component analysis(PCA),correlation analysis,cluster analysis were used to analyze the data to re-veal characteristics of constituent composition and predominant components of summer-autumn tea.[Result]Processing techniques affected tea infusion color:color difference(ΔE)and red-green degree(a*)of yellow tea and black tea were significantly higher than green tea(P<0.05,the same below);green tea showed a higher lightness(L*);yellow-blue de-gree(b*)was the highest in yellow tea and lowest in black tea.Compared with spring green tea,summer-autumn green tea exhibited high polyphenol and low amino acid,as it had higher contents of tea polyphenols(24.12%),total catechin content(210.13 mg/g),and total flavonoids(129.06 mg/g),with strong antioxidant capacity[1,1-diphenyl-2-picrylhy-drazyl(DPPH)radical scavenging rate of 59.51%,and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammo-nium salt(ABTS)radical scavenging rate of 53.10%,and ferric reducing antioxidant power of 559.96 mg/g],but its to-tal free amino acid content(2.68%)was relatively low.Different processing techniques were one of the key factors cau-sing differences in tea constituents,and the contents of phenolic substances(tea polyphenols and catechin components)and soluble sugar content in black tea were significantly lower than those in green tea.Correlation analysis showed that tea polyphenols,catechin components,and total flavonoid content were positively correlated with antioxidant capacity,and catechin components were negatively correlated with free amino acid components.In PCA,the cumulative contribution rate of the first principal component(PC1)and the second principal component(PC2)reached 71.6%,effectively reflec-ting the compositional differences in the main tea constituents;the loading plot showed that tea polyphenols,catechin components,total flavonoids,antioxidant capacity,isoleucine,and leucine were the key discriminatory indicators for different tea samples.According to cluster analysis,tea samples were divided into five categories based on fermentation degree and seasonal characteristics,confirming the marked effects of different plucking seasons and processing tech-niques on tea quality.[Conclusion]Tea quality characteristics are determined by plucking seasons and processing tech-niques.Green tea,black tea,and yellow tea processed from spring tea leaves all exhibit good quality,each with its own advantages;summer-autumn tea shows certain deficiencies in flavor performance,with poor processing suitability for green tea,but it demonstrates obvious advantages in functional component accumulation and antioxidant capacity,indi-cating high potential for resource development and utilization.