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Journal of Tea Science ›› 2022, Vol. 42 ›› Issue (4): 525-536.doi: 10.13305/j.cnki.jts.2022.04.011

• Research Paper • Previous Articles     Next Articles

Effects of Air Conditions Preset for Withering on Flavor Quality and Chemical Profiles of White Teas

ZHANG Yinggen, XIANG Lihui, CHEN Lin*, LIN Qingxia, SONG Zhenshuo, WANG Lili   

  1. Tea Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350013, China
  • Received:2022-02-08 Revised:2022-04-02 Online:2022-08-15 Published:2022-08-23

Abstract: To realize the quality control of white tea based on withering environment, indoor temperature and relative humidity were preset at (30±2)℃ with RH (35±5)% or (20±2)℃ with RH (55±5)% to investigate the effects of four different air conditions on the sensory quality and chemical profiles of 6 tea cultivars (Camellia sinensis), including Fuan-dabaicha, Huangdan, Huangguanyin, etc. According to whether the indoor temperature and relative humidity were mutually switched at the point when the weight loss rate of tea shoots reached 45% during the whole withering procedure, the levels of each withering treatment were named as Low-Low, Low-High, High-Low and High-High, respectively. The results show that the flavor quality of white tea was mainly determined by the physical and chemical characteristics of raw materials (tea cultivars). White teas obtained under Low-Low treatment had a slightly light taste and a little grassy flavor, while the white teas from the same tea cultivars had the similar quality characteristics in appearance and soup color when they were treated with High-High and Low-High, just as High-Low and Low-Low during withering. The ultraviolet and near-infrared spectra of all white tea samples had similar fluctuations, and the near-infrared spectra could provide more abundant chemical information for their pattern recognition. The contents of gallic acid, epicatechin gallate, gallocatechin, caffeine and theobromine in white tea samples were different among tea cultivars, but withering treatment had no significant effect on the contents of detected biochemical components (catechins and purine alkaloids). Moreover, principal component analysis based on ultraviolet spectra, especially near-infrared spectra or biochemical compositions of white tea samples could better discriminate white tea samples into the same groups according to their raw materials (tea cultivars). The effects of different air conditions on the profiles of spectra or biochemical compositions were exclusively drowned by the characteristics of raw materials. However, the influence of withering treatment on the profiles of near-infrared spectra and biochemical compositions of white tea samples manufactured from different raw materials could be effectively revealed by multilevel principal component analysis, and the classification and identification results of all white tea samples were almost consistent with the characteristics of sensory quality. These facts could provide a reference for the technological regulation of white tea flavor quality.

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