Optimization of Preparation Technology of Instant Tibetan Tea and Analysis of Its Functional Components and Antioxidant Activity

To prepare instant Tibetan tea, the extraction technology was optimized by single factor experiment and Box-Behnken response surface design, with the yield of instant Tibetan tea, the extraction of polysaccharide and the extraction of polyphenols as the evaluation index.The results showed that the optimal extraction conditions were as follows: solid-liquid ratio 1:53 (g/mL), extraction temperature 98.5 ℃, extraction time 1.5 h, and extraction 3 times. Under the optimal extraction conditions, the yield of instant Tibetan tea was 29.72%±0.13%, the extraction of polysaccharide was (6.06±0.03) g/100 g, and the extraction of Tibetan tea polyphenols was (6.27±0.05) g/100 g. Ten kinds of functional components in instant Tibetan tea were detected by UHPLC-QqQ-MS/MS, EGCG, GA, GCG and ECG were the main catechins. The contents of EGC, EGCG, quercetin in freeze-dried instant Tibetan tea were higher than those in spray-dried instant Tibetan tea (P<0.05). The IC₅₀ of freeze-dried instant tea on scavenging ability of DPPH and ABTS free radicals were 0.247 and 0.417 mg/mL, and the IC₅₀ of spray-dried instant tea on scavenging ability of DPPH and ABTS free radicals were 0.339 and 0.443 mg/mL. Therefore, the instant Tibetan tea powder has good antioxidant activity.