关键词: 绿茶, 超声辅助, 常温冲泡, 条件, 品质

Abstract: To shorten the time of brewing green tea at room temperature and get good quality, the study makes use of ultrasound-assisted brewing at room temperature. Screening optimized brewing conditions, and comparing it with the quality of standard boiling water brewing through sensory evaluation and chemical analysis of major taste components and aroma compounds. The results showed that the optimization brewing conditions of ultrasound-assisted brewing green tea at room temperature is 5 g tea, room temperature water 150 mL (the ratio of the tea and water is 1: 30), ultrasound brew 10 min. In this condition, the content of water extracts, polyphenols and caffeine are lower and the content of amino acids is higher compared with standard boiling water brewing tea. Both aroma components are substantially the same. However, tea brewing at room temperature lacks substances that having unpleasant fat odor, like octanal, (E)-2-Octenal, increase fragrance substances like alpha.-linalool, trans-2-hexenyl caproate. The study initially identifies practical feasibility of ultrasonic-assisted brewing green tea at room temperature, which tastes fresh and mellow, the aroma is fresh and last long, the overall quality is better than the standard boiling water brewing. Ultrasonic method is particularly suitable for industrial extraction of tea, it can greatly save energy and reduce emissions.

Key words: green tea, ultrasound-assisted, brewing at room temperature, condition, quality