Effect of Pile-up Processing Duration on the White Tea Aroma Analyzed by Chemometrics Approaches
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Abstract:
Pile-up is a tea manufacture process,which is beneficial to the transformation of tea aroma.. In this study, the effect of pile-up processing duration on the white tea aroma was investigated, and the relationship between sensory aroma and the changes of volatile organic compounds (VOCs) along different durations was analyzed. The sensory evaluation results indicated that pile-up treatment could improve sweetness of white tea, but decreased freshness. A total of 55 VOCs were characterized through headspace-solid phase micro-extraction (HS-SPME) coupled with gas chromatography-triple quadrupole mass spectrometry (GC/MS/MS). The VOCs profiles showed that pile-up had little effect on the composition changes, but the content changed significantly. Chemometric approaches were applied to select and analyze the 37 differential VOCs patternsin white tea. The results showed that all samples of different pile-up treatments were distinguished based on the principle component analysis and hierarchical cluster analysis, of which the difference between samples was obvious before and after pile-up processing. The content of 2-phenylethanol, benzaldehyde, phenylacetaldehyde increased after pile-up treatment, as well as the content of β-cyclocitral, (E)-2-octenal and α-ionone widely increased in post-pile-up samples, which might be the cause of stronger sweetness flavor. However, the content of 1-hexanol, (E,E)-2,4-hexadienal and octanal in post-pile-up samples decreased widely, which might be related to the reduction of freshness. The 32h pile-up was considered as the optimum duration for processing white tea. The introduction of chemometric approaches in VOCs analysis facilitated in revealing the variations and exploring the biochemical patterns among samples.
