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題 名 | 萎凋溫度與濕度對白茶品質之影響(2)--萎凋條件對白茶化學成分之影響=Effects of Withering Temperature and Humidity on the Quality of White Tea (Ⅱ)--Chemical Contents of White Tea as Affected by Duration of Withering |
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作 者 | 林金池; 陳世雄; | 書刊名 | 臺灣茶業研究彙報 |
卷 期 | 18 1999.06[民88.06] |
頁 次 | 頁101-118 |
分類號 | 473.4 |
關鍵詞 | 茶; 萎凋; 溫度; 濕度; 化學成分; White tea; Withering; Temperature; Humidity; Chemical components; |
語 文 | 中文(Chinese) |
中文摘要 | 茶菁在夏季自然環境下萎凋製造白茶,試驗結果顯示茶多元酚類含量在萎凋前30小時維持在22%左右,萎凋60小時,茶多元酚類含量降低至15%。茶湯pH值在萎凋期旬由6.3降至5.9。胺基酸含量隨萎凋時間延長而增加。白茶自然萎凋期間,茶湯明亮度(L值)隨萎凋時間延長而降低,a值(綠色)萎凋後期明顯減少,b質(黃色)則急速增加,茶湯水色偏黃。 本試驗夏茶控制萎凋溫度在32℃,測定不同濕度處理之CO2濃度變化,顯示在高濕(80%)條件下,呼吸作用可以持續進行較長之時間,有利於茶菁各項代謝作用之持續進行,茶葉中之化學成分也可順利轉化,白茶成茶品質較佳。 茶葉化學成分經變方分析結果顯示,萎凋溫、濕度對白茶可溶性成分(solublesolids)、總游離胺基酸(total amino acid )、咖啡因(caffeine)、茶多元酚類(polyhenols)含量及pH值均有顯著影響。低溫高濕短時間萎凋,白茶pH值、茶多元酚類、可溶性成分較高。茶葉游離胺基酸在萎凋期間明顯增加,其中春、秋茶胺基酸含量較夏茶為高。咖啡因含量有萎凋過程也顯著增加。三白茶之茶多元酚類及可溶性成分,以夏茶含量最高,秋茶次之,春茶最低。 白茶茶湯明亮度(L值),以低溫高濕及高溫高濕萎凋環境生產之白茶,茶湯較明亮。隨萎凋濕度降低時間延長,茶湯明亮度隨之降低。但茶湯a值(負值為綠色)在此環境下反而降低,表現恰與L值相反,即綠色成分有增加之趨勢。B值(正值為黃色)和△E值之變化趨勢相當一致,均以高濕環境下,b值和△E較低,茶湯呈杏黃色。但在高溫低濕環境下,茶葉失水快速,茶棄易於紅變,發酵程度較重,茶湯b值及△E值增加2∼3倍,其中又以春茶增加最多。 |
英文摘要 | Experiment results showed that withering under natural circumstances, polyphenols content of summer white tea kept the level around 22% at the beginning 30 hours. But as withering time extended after 30hours, since dehydration of the tea leaves, oxidation of the polyphenols was promoted. That caused polyphenols reduced to 15%. The pH of infusion declined from 6.3 to 5.9 and amino acid content increased during withering. The brightness (value L) of infusion of white tea tended to decrease as withering time increased. Thus greenness (value a) decreased and yellowish (value b) increased, caused a yellowish infusion color. A higher CO2 content in the atmosphere was measured when summer tea withering under 32℃ and high humidity. Which means a lasting and longer period for respiration of tea leaves under higher air moisture condition. And a higher quality of white tea resulted under well metabolism and conversion of components in tea leaves. The effects of withering temperature, humidity, and duration on the quality and chemical components were investigated. Results from analyses of variance showed that temperature and humidity in withering affected the soluble solids, total amino acid, caffeine, polyphenols, and pH of white tea infusion. When withering in low temperature, high humidity, and short duration, a higher pH, polyphenols, Soluble solids infusion of white tea was resulted. During withering, free amino acid increased significantly in the white tea. Amino acid contents in the spring and fall scason were higher than the summer. Caffeine contents also increased during withering. Polyphenols and soluble solids contents in tea produced from summer are much higher than that from the fall, and spring, which is the lowest. The best and brighter color of infusion of white tea was produced under withering condition of low temperature with high humidity or high temperature and humidity. As the humidity decreased and time extended during withering, a poor infusion color white tea were produced. Under such environments, value a (greenness) of infusion declined. Value b (yellow) and △E are lower under high humidity, and infusion became yellowish. If tea withering under high temperature and low humidity, rapid dehydration caused a heavier fermentation and tea leaves became reddish, value b and △E in the infusion increased 2-3 times. Poor quality of white tea was resulted by withering in high temperature and low humidity, especially in the spring tea processing. |
本系統中英文摘要資訊取自各篇刊載內容。