压饼及湿热工艺对白茶品质和抗氧化活性的影响

茶饼便于保存和携带,茶叶在压制及湿热工艺中对其品质的影响也是茶叶加工中值得研究的问题。本文探究了压饼和湿热工艺对政和白茶特征成分和抗氧化活性的影响。选取政和白毫银针、白牡丹、贡眉和寿眉茶样,以及寿眉在压饼三个阶段的茶样为研究对象,测定茶样中的水浸出物、茶多酚、儿茶素、可溶性蛋白质、氨基酸、可溶性糖、黄酮类、茶多糖和没食子酸的含量。结果表明,经过压饼尤其是湿热压制工艺后,寿眉的水浸出物、茶多酚、儿茶素、可溶性蛋白质、黄酮类和没食子酸含量均显著增加,而可溶性糖、茶多糖和氨基酸含量显著降低。湿热处理后,四款白茶茶汤内含物质丰富且抗氧化能力均显著增加,有利于贡眉和寿眉的品质提升,如儿茶素含量及酯型儿茶素比例、汤色明亮度和滋味均有明显改善,而对于相对较嫩的白毫银针和白牡丹则无明显变化。

Effect of compressing and heat-moisture treatment on the quality and antioxidation capability of white tea

Tea cake is easy to be stored and transported.It is interesting to study the influence of the pressuring and heat-moisture treatment on the quality of pressed white tea.This study was set to investigate the effect of two processing methods on characteristic components of white tea cake.Four kinds of Zhenghe white tea including Baihaoyinzhen, Gongmei, Shoumei and Baimudan were used in this experiment.It was found that the contents of aqueous extracts, tea polyphenols, catechins, soluble proteins, flavonoids and antioxidant capacity in white tea increased significantly after steaming and compressing treatment, while contents of soluble sugars, tea polysaccharides and amino acid significantly decreased.The effect of heat-moisture treatment on the characteristics of the four white teas showed the same trend.By comparison of the catechins composition, chromatism and sensory evaluation results, it was found that the heat-moisture treatment is beneficial to the quality of Gongmei and Shoumei.Heat-moisture treatment had no significant possitive effect on Baihaoyinzhen and Baimudan.