Comparative Study on Functional Components of Two Types of Black Tea Powder and Their Ameliorative Effects on Colitis in Mice

This study aimed to analyze variations in the major functional components and characteristic aroma profiles of black tea powders prepared through two distinct processing techniques, and further investigate their protective effects against dextran sulfate sodium (DSS)-induced colitis in mice. Fifty 8-week-old C57BL/6J mice were randomly assigned to five groups: normal control (NC), DSS-induced colitis model (DSS), EGCG positive intervention (EGCG, 20 mg·kg-1), instant black tea powder intervention (SU, 300 mg·kg-1) and trans-solubilized black tea powder intervention (ZHUAN, 300 mg·kg-1). The results demonstrate that: (1) The contents of free amino acids, soluble proteins, tea polyphenols and caffeine underwent significant alterations during processing due to methodological differences. (2) Characteristic volatile compounds (including linalool, leaf alcohol, α-terpineol, methyl salicylate, and geraniol) were commonly detected in both tea powders. (3) Both tea powders significantly alleviated DSS-induced colitis symptoms, as evidenced by reduced body weight loss and colon shortening, decreased pro-inflammatory cytokine (TNF-α, IL-1β and IL-6) levels in serum and colon tissue, mitigated oxidative stress injury (decreased MDA content and elevated SOD activity), and improved intestinal barrier permeability (up regulated expressions of tight junction proteins ZO-1 and Occludin, and decreased serum LPS levels). These findings indicate that instant and trans-solubilized black tea powders exhibit protective effects against DSS-induced murine colitis.