茶科技 | 綠茶長(zhǎng)時(shí)間低溫沖泡，也能獲得較好的健康功效

英文摘要In response to growing demand for functional, minimally processed foods and rising energy costs, various brewing conditions for low-temperature green tea production were explored as an alternative to high-temperature processing. Optimal polyphenol extraction was achieved at 85 °C for 30 min using distilled water and finely ground leaves (< 500 μm). Although similar conditions are recommended for tap water, this resulted in a tremendous reduction in both catechin yields and antioxidant capacity (AC), as determined by spectrophotometric and chromatographic analyses. Lowering extraction temperature to 20 °C and brewing for 12 h with distilled water led to exceptionally high AC, along with higher yields of vitamin C, vitamin B2, epicatechin, and epigallocatechin compared to any high-temperature brewing method. Notably, these benefits were evident only when whole leaves were used, rather than tea powder. Further research is needed to address technological challenges for industrial green tea production with distilled water.

代表性圖片

▲ 實(shí)驗(yàn)設(shè)計(jì)

▲不同沖泡條件下GTI（綠茶浸泡液） 的 pH 比較

▲不同沖泡條件下GTI的游離氨基氮濃度（FAN）比較

▲不同沖泡條件下GTI 的甲基黃嘌呤濃度比較

▲不同沖泡條件下GTI的總多酚含量和抗氧化能力（DPPH、FRAP）比較

▲不同沖泡條件下GTI的PCA 載荷圖（沖泡用水、溫度時(shí)間、茶葉形態(tài)）

導(dǎo)讀本文于近日由波蘭羅茲技術(shù)大學(xué)的研究團(tuán)隊(duì)在線發(fā)表于《Food Chemistry》。研究選用日本整葉綠茶和粉作為實(shí)驗(yàn)材料，用自來(lái)水和蒸餾水在85℃高溫短時(shí)沖泡10min/30min，5℃或20℃低溫長(zhǎng)時(shí)沖泡2h/6h/12h，探討了不同沖泡條件對(duì)不同形態(tài)綠茶的浸提液營(yíng)養(yǎng)成分及功能成分的影響。主要發(fā)現(xiàn)如下：

（1）沖泡水質(zhì)：自來(lái)水雖能通過(guò)減少對(duì)拮抗性酚類物質(zhì)的提取，提高某些維生素（B1和B6）的可利用性，但使用蒸餾水比自來(lái)水更能增強(qiáng)表兒茶素、維生素B、鐵離子和游離氨基酸的提取。（2）沖泡條件：高溫（85°C）沖泡30min會(huì)降低非酯型兒茶素的穩(wěn)定性，并減少水溶性維生素的含量，尤其是維生素C和游離氨基酸。低溫沖泡（20°C，12h）可最大限度地提取兒茶素、維生素和抗氧化能力。（3）茶葉形態(tài)：使用完整茶葉可以增加維生素B2的含量。 （4）獲取高質(zhì)量綠茶浸泡液的最佳條件：使用蒸餾水在20°C下沖泡整片葉子12h。

審稿：中國(guó)農(nóng)業(yè)科學(xué)院茶葉研究所 譚俊峰副研究員