Friedman Mendel, Levin Carol E, Choi Suk-Hyun, Lee Seung-Un, Kozukue Nobuyuki
Western Regional Research Center, U.S. Dept. of Agriculture, Albany, CA, USA.
J Food Sci. 2009 Jun;74(5):C406-12. doi: 10.1111/j.1750-3841.2009.01185.x.
To develop a better understanding of compositional changes occurring during the production of commercial teas, we determined by high-performance liquid chromatography (HPLC) changes in ingredient levels during each of several manufacturing steps used to produce Kamairi-cha, a premium green tea. Kamairi-cha uses pan-frying instead of the usual blanching technique to inactivate the enzymes responsible for producing traditional black tea. The resulting tea lacks the characteristic bitterness of green tea, producing a green tea that is described as sweet tasting. The processing steps used to produce this pan-fried tea were as follows: 1st roasting, 1st rolling, 2nd roasting, 2nd rolling, 1st firing, and 2nd firing. The results show that during production at temperatures up to 300 degrees C, raw leaves lost (in percent) 97.3 water, 94 two chlorophylls, 14.3 seven catechins, and 2.75 caffeine. A separate analysis showed that the final product contained 21.67 mg/g dry wt of the biologically active amino acid theanine. The results of this 1st report on changes in individual catechins and other tea ingredients in tea leaves during pan-frying make it possible to select production conditions that maximize levels of beneficial tea ingredients. The possible significance of the results for the human diet is discussed.
为了更好地了解商业茶叶生产过程中发生的成分变化，我们通过高效液相色谱法（HPLC）测定了用于生产高级绿茶香煎茶的几个制造步骤中每种成分水平的变化。香煎茶使用煎炒而非通常的热烫技术来使负责生产传统红茶的酶失活。由此产生的茶缺乏绿茶特有的苦味，产生一种被描述为甜味的绿茶。生产这种煎茶的加工步骤如下：第一次烘焙、第一次揉捻、第二次烘焙、第二次揉捻、第一次干燥和第二次干燥。结果表明，在高达300摄氏度的温度下生产期间，生叶损失了（百分比）97.3%的水分、94%的两种叶绿素、14.3%的七种儿茶素和2.75%的咖啡因。一项单独的分析表明，最终产品含有21.67毫克/克干重的生物活性氨基酸茶氨酸。这份关于煎茶过程中茶叶中各儿茶素和其他茶叶成分变化的第一份报告结果使得选择能使有益茶叶成分水平最大化的生产条件成为可能。文中讨论了这些结果对人类饮食可能具有的意义。
