| Summary: | 碩士 === 國立嘉義大學 === 農藝學系研究所(Graduate Institute of Agronomy) === 98 === The main purpose of this study was to investigate the vatiation of chemical components of tea which grown in different altitudes during roasting processes. The Dung-ding type Paochung tea crude tea samples were collected in Nantou and Chiayi county. The result showed that total chlorophyll of spring tea was significantly decreased with increasing altitude. As altitude was increasing, total polyphenols of spring tea were significantly decreased. And, total free amino acid and reducing sugar were raised with increasing altitude. However, because of production season regulation, chemical components and tea liquor in winter tea were independent on altitude.. The content of catechin of spring tea was highest in low altitude. The tea cultivated at the altitude of 600 m produced the highest EGC (epigallocatechin), C (catechin), and EGCG (gallate epigallocatechin). On the other hand, the tea cultivated at the altitude of 300 m produced the highest EC (epicatechin) and ECG (epicatechin gallate). The harvesting season at different altitudes also affected the tea chemical components. Total free amino acid content of spring tea was higher than that of winter tea at every altitude; However, there was the highest content of reducing sugar in winter tea. Soluble solid content of winter teas was higher than that of spring tea, except for
the samples collected from the altitude of 600 m.
Total chlorophyll of all tea samples was decreased gradually during the roasting processes. Total polyphenols of most tea samples were a little bit decreased after roasting, another part of tea samples which are winter
tea at the altitudes of 300 m were increased.
As the roasting duration was extended, the L values of tea liquor was significantly decreased and the a and b values wrer increased. The spring tea samples collected from high altitude areas had better tea quality than other areas. Moreover, roasting treatment improved the quality of tea especially the spring tea and winter tea grown at the altitude of 1,200 m.
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