Wang Jie, Zhang Ying, Liu Yan, Zhang Shaorong, Yuan Linying, Zhong Yingfu, Wu Xiuhong, Yang Juan, Xu Ze
Tea Research Institute, Chongqing Academy of Agricultural Sciences, Chongqing 402160, China.
College of Food Science, Southwest University, Chongqing 400715, China.
Foods. 2022 Oct 20;11(20):3269. doi: 10.3390/foods11203269.
The supercritical CO-based decaffeination (SCD) method can be used to prepare decaffeinated tea, but its overall effect on the phytochemicals, volatiles, and sensory qualities of green and black teas is still unclear, and its suitability to prepare decaffeinated green and black teas still needs to be compared. This study revealed the effect of SCD on phytochemicals, volatiles, and sensory qualities in black and green tea prepared from the same tea leaves, and compared the suitability of preparing decaffeinated green and black teas using SCD. The results showed that the SCD could remove 98.2 and 97.1% of the caffeine in green and black tea, respectively. However, it can cause further losses of phytochemicals in green and black teas, specifically the loss of epigallocatechin gallate, epigallocatechin, epicatechin gallate, and gallocatechin gallate in green tea and the loss of theanine and arginine in green and black teas. After the decaffeination, both green and black teas lost some volatiles but also generated new volatiles. Especially, the fruit/flower-like aroma, ocimene, linalyl acetate, geranyl acetate, and D-limonene, were generated in the decaffeinated black tea, while herbal/green-like aroma, β-cyclocitral, 2-ethylhexanol, and safranal, were generated in the decaffeinated green tea. The overall acceptance of decaffeinated green tea decreased due to the substantial reduction in bitterness and astringency, while the overall acceptance of decaffeinated black tea significantly increased. Therefore, SCD is more suitable for the preparation of decaffeinated black tea.
基于超临界CO₂的脱咖啡因（SCD）方法可用于制备脱咖啡因茶，但其对绿茶和红茶的植物化学物质、挥发性成分及感官品质的总体影响仍不明确，其制备脱咖啡因绿茶和红茶的适用性仍需比较。本研究揭示了SCD对由相同茶叶制备的红茶和绿茶中植物化学物质、挥发性成分及感官品质的影响，并比较了使用SCD制备脱咖啡因绿茶和红茶的适用性。结果表明，SCD分别可去除绿茶和红茶中98.2%和97.1%的咖啡因。然而，它会导致绿茶和红茶中植物化学物质的进一步损失，特别是绿茶中表没食子儿茶素没食子酸酯、表没食子儿茶素、表儿茶素没食子酸酯和没食子儿茶素没食子酸酯的损失，以及绿茶和红茶中茶氨酸和精氨酸的损失。脱咖啡因后，绿茶和红茶都损失了一些挥发性成分，但也产生了新的挥发性成分。特别是，脱咖啡因红茶中产生了水果/花香样香气，如罗勒烯、乙酸芳樟酯、乙酸香叶酯和D-柠檬烯，而脱咖啡因绿茶中产生了草本/绿色样香气，如β-环柠檬醛、2-乙基己醇和藏红花醛。脱咖啡因绿茶的总体接受度因苦味和涩味大幅降低而下降，而脱咖啡因红茶的总体接受度显著提高。因此，SCD更适合制备脱咖啡因红茶。
