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題 名 | 兒茶素溶液的穩定性=The Stability of the Solution of Catechins |
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作 者 | 陳英玲; 林書妍; | 書刊名 | 臺灣茶業研究彙報 |
卷 期 | 24 民94.11 |
頁 次 | 頁77-90 |
分類號 | 341.96 |
關鍵詞 | 兒茶素溶液; 表異構物; 穩定性; Catechin solutions; Epimers; Stability; |
語 文 | 中文(Chinese) |
中文摘要 | 茶湯中的兒茶素除了自然氧化作用外,表異構化作用應是主要反應之一。利用HPLC估算高溫下個別兒茶素的表異構化作用,最主要的變化為由epi-順式結構轉變為nonepi-反式結構,逆反應則屬少量。即順式立體結構較反式結構容易產生表異構化作用。由此可知反式結構在自然界較為穩定。茶中的兒茶素絕大多為順式且以EGCG及EGC為最多,所以兒茶素水溶液因表異構化作用頻繁而難以保存。 粗兒茶素在pH3~4溶液中室溫下貯存一個月,其重要兒茶素成分EGCG及EGC減低率<5%;即使在85℃下EGCG酸性溶液至少能維持1~2天無表異構物--GCG產生。兒茶素在酒精溶液中(15~75%),雖較在純水中安定,但在存放14~28天之間可發現而兒茶素明顯減少趨勢。 |
英文摘要 | Tea catechins undergo many chemical reactions in pure water such as spontaneous oxidation and epimerization. The predominant change appears to be epimerization from the epistructure to the nonepistructure. Catechins with 2R, 3R configuration (cis-form) are easier to achieve epimerization than that of 2R, 3S (trans-form). It was shown that the configuration of 2R, 3S is more stable in nature. Among eight individual catechins, the contents of EGCG and EGC were above 70% of total catechins. Tea catechins which almost to be cis-forms are difficult to be stored in pure water because of their frequent epimerization. Grude catechins in pH 4 buffer of which EGCG and EGC decrease under about 5% have been stored at 25°C for 30 days. EGCG also had not been found its epimer-GCG in pH 4 buffer at 85°C for one or two days. Catechins in alcoholic solution are more stable than that of in pure water. It was found that catechins had decreased significantly to be stored from the fourteenth to twenty-eighth days. |
本系統中英文摘要資訊取自各篇刊載內容。