The epimers of catechin include epicatechin, epigallocatechin and epigallocatechin gallate, and others. They are important bioactives that have salutary effects, and hence are valuable. For ascertaining biologically-safe and green extraction methods that are non-thermal, this review evaluates the efficiencies of ultrasound assisted extraction (UAE) and supercritical (SC) fluid extraction (with CO₂). Standalone SC-CO₂ could be preferred over UAE, given its selectivity (purer product, no co-extracts) and absence of downstream processing. GRAS solvents as water and ethanol or a hydro-alcoholic mix are preferable for UAE. However, considering the core competency of ultrasound in disrupting cell organelles, a tandem approach with sequential SC extraction is recommended to justify process economics and ensure quality yield of catechin using green technologies.

中文翻译：

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儿茶素回收的超临界流体和超声辅助绿色提取技术

儿茶素的差向异构体包括表儿茶素、表没食子儿茶素和表没食子儿茶素没食子酸酯等。它们是具有有益效果的重要生物活性物质，因此很有价值。为了确定非热法的生物安全和绿色萃取方法，本综述评估了超声辅助萃取 (UAE) 和超临界 (SC) 流体萃取（使用 CO ₂）的效率。独立 SC-CO ₂考虑到其选择性（更纯的产品，无共提取物）和没有下游加工，可能比阿联酋更受欢迎。阿联酋优选使用 GRAS 溶剂，如水和乙醇或水醇混合物。然而，考虑到超声波在破坏细胞器方面的核心能力，建议采用连续 SC 提取的串联方法来证明工艺经济性并确保使用绿色技术的儿茶素的质量产量。