Determination of the total phenolic content of commercially available green teas using an in vitro gastrointestinal system: a preliminary study

Palamutoğlu M. İ., SİPAHİ S., Palamutoğlu R., Kasnak C.

Italian Journal of Food Science, vol.38, no.1, pp.298-307, 2026 (SCI-Expanded, Scopus) identifier

  • Publication Type: Article / Article
  • Volume: 38 Issue: 1
  • Publication Date: 2026
  • Doi Number: 10.15586/ijfs.v38i1.3356
  • Journal Name: Italian Journal of Food Science
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Compendex, Directory of Open Access Journals
  • Page Numbers: pp.298-307
  • Keywords: catechin, green tea, HPLC, in vitro assays, phenolic compounds
  • Acibadem Mehmet Ali Aydinlar University Affiliated: Yes

Abstract

This preliminary study evaluated changes in total phenolic content and catechin and epicatechin levels in commercially available green teas through an in vitro digestion. Samples (1.5% dry tea in 100 mL water at 80°C) were analyzed for total soluble solids, pH, and color. The initial total phenolic content ranged from 381.19–1779.50 µg gallic acid equivalent/mL, decreasing to 315.22–1266.37 µg/mL in the small intestine. Epicatechin decreased from 7.64–13.97 µg/mL to 4.53–9.19 µg/mL, while catechin dropped from 13.13–24.03 µg/mL to 5.43–14.03 µg/mL. Significant decreases occurred across digestion, indicating reduced bioaccessibility of green tea polyphenols that may influence antioxidant and health effects.