Abstract The pressurized hot water extraction (PHWE) of six representative compounds from black tea brick was investigated in a semi-continuous extractor under the conditions of various temperatures (120–180 °C) and water flow rates (6–18mLmin-1). The extracted solutions were dark brown liquid suspensions, and a significant proportion of the six compounds (70.7–92.0%) was found in the supernatant phase after centrifugation. Theophylline is the most stable compound with respect to increasing temperature and extraction time. Epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) were sensitive to temperature, while the other compounds (caffeine, catechin, and gallocatechin gallate (GCG)) were affected by both temperature and water flow rate. The optimum conditions were found to be 160 °C and 12 mL min−1. Compared to the traditional tea brewing (TTB) method, PHWE can achieve significantly higher extraction yields of theophylline, caffeine, catechin, and GCG.

中文翻译：

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半连续加压热水提取红茶

摘要 在不同温度 (120–180 °C) 和水流速 (6–18mLmin-1) 条件下，在半连续萃取器中研究了红茶砖中六种代表性化合物的加压热水萃取 (PHWE)。提取的溶液是深棕色液体悬浮液，离心后上清相中发现了很大比例的六种化合物（70.7-92.0%）。茶碱是温度升高和提取时间增加最稳定的化合物。表儿茶素没食子酸酯 (ECG) 和表没食子儿茶素没食子酸酯 (EGCG) 对温度敏感，而其他化合物（咖啡因、儿茶素和没食子儿茶素没食子酸酯 (GCG)）受温度和水流速的影响。发现最佳条件为 160 °C 和 12 mL min-1。