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Journal of Tea Science ›› 2025, Vol. 45 ›› Issue (4): 699-711.doi: 10.13305/j.cnki.jts.20250619.001

• Research Paper • Previous Articles     Next Articles

Differences in Digestive Stability of Catechins in Dry Tea and Instant Tea Powder

ZHANG Mengxue1,2,3, JIANG Heyuan2,*, WANG Weiwei1, YE Shuixin1,4   

  1. 1. Key Laboratory of Special Economic Animal and Plant Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China;
    2. Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences, Chengdu 610299, China;
    3. Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China;
    4. College of Food and Health, Zhejiang A & F University, Hangzhou 311300, China;
  • Received:2025-01-07 Revised:2025-04-16 Online:2025-08-15 Published:2025-08-15

Abstract: The effects of different pH and digestive enzymes in tea soup on tea polyphenols (TP), catechins (CATE) and their antioxidant activities were investigated by using an in vitro simulated digestion model, and the differences between dry tea and instant tea powder were compared. The TP concentration was determined by Folin phenol method, and the catechins were quantitatively analyzed by high performance liquid chromatography (HPLC). The antioxidant activities of the two kinds of tea soups were comprehensively evaluated by Ferric reducing ability of plasma (FRAP), 1,1-diphenyl-2-trinitrophenylhydrazine free radical (DPPH) and 2,2ʹ- diazo-bis-3-ethylbenzothiazoline-6-sulfonic acid free radical (ABTS). The results show that the TP concentration (874.19 mg·L-1) of black instant tea powder before simulated digestion was 1.59 times that of dry tea soup (551.50 mg·L-1), the cate concentration (239.58 mg·L-1) was 1.68 times that of dry tea soup (142.98 mg·L-1), and the antioxidant activity was about twice that of dry tea soup. After gastrointestinal simulated digestion, the stability of tea soup cate and antioxidant activity of black instant tea powder were lower than that of dry tea, which may be related to the high proportion of epigallocatechin gallate (EGCG)+epigallocatechin (EGC) in instant tea soup and its intestinal degradation law. Both pH 2.0 and pH 7.0 decreased the antioxidant activity of tea soup, and the effect of acidic pH was greater. The addition of pepsin, TP and cate increased the antioxidant capacity of tea soup, while the addition of bile salt and trypsin decreased the FRAP value of tea soup. To sum up, the preparation of instant tea powder, pH and the phased action of digestive enzymes could affect the digestion stability of catechins in tea. By optimizing the extraction parameters of instant tea, the changes of catechins in tea can be reduced, and the influence of gastric acid environment during instant tea drinking can be avoided, so as to improve the bioavailability of catechins in tea leaves.

Key words: dry tea, instant tea powder, pH, digestive enzymes, tea polyphenols, antioxidant activity

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