Comparative Analysis of the Quality Components in Xinyang White Teas Collected and Processed in Different Seasons
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Abstract:
In this work, 8 kinds of catechins, 6 kinds of flavonoids, 2 kinds of phenolic acids, 3 kinds of purine alkaloids and other quality components contents in 18 kinds of Xinyang white teas processed from the fresh tea leaves of Spring, Summer and Autumn were analyzed by methods such as high performance liquid chromatography (HPLC). The quality components of the Xinyang white teas collected and processed in different seasons were compared and analyzed. Principal component analysis (PCA) and hierarchical clustering analysis (HCA) could classify Xinyang white tea samples into spring white tea, summer white tea and autumn white tea based on the processing seasons. Through the independent-samples t-test and one-way analysis of variance, the differences in the quality components (such as catechins, flavonoids and purine bases) of the Xinyang white teas collected and processed in different seasons were investigated. The results showed that there were significant (p<0.01) or extremely significant (p<0.001) differences in the quality components of the Xinyang white teas collected and processed in different seasons; The contents of (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG) and ellagic acid in the spring white tea (33.26, 59.30 and 2.81 mg/g, respectively) were extremely significantly (p<0.001) higher than those in the summer or autumn white teas. The contents of (-)-catechin gallate (CG), (-)-gallocatechin gallate (GCG), taxifolin, rutin, myricetin, kaempferol, quercetin and luteolin in the summer white tea (0.72, 4.40, 0.84, 2.40, 0.97, 0.21, 0.25 and 0.11 mg/g, respectively) were extremely significantly (p<0.001) higher than those in the autumn white tea. The contents of (+)-catechin (C), (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), gallic acid, caffeine and theobromine (4.98, 14.35, 27.02, 10.10, 36.85 and 1.53 mg/g) in the autumn white tea were extremely significantly (p<0.001) higher than those in the spring or summer white tea. This study revealed the quality characteristic of Xinyang white teas and the differences in the quality components of Xinyang white teas harvested and processed in spring, summer and autumn seasons. These results provide a scientific basis for the distinguishing white teas and other teas harvested and processed in different seasons.
