Comparative evaluation of high-pressure processing and conventional pasteurization in cold brew green tea: In vitro digestibility, bioavailability, and nutrient stability

Abstract

High-pressure processing (HPP) is a non-thermal alternative to thermal pasteurization (Ps) for preserving cold-brewed green tea. This study compared HPP (300, 450, and 600 MPa for 5 and 10 min) with Ps for quality, microbial safety, and in vitro digestive stability. Moderate HPP treatments preserved color, ascorbic acid, and catechins effectively. HPP retained more non-galloylated catechins (GC, EGC, and EC) than Ps, which could reduce bitterness and astringency, though formal sensory evaluation is needed to confirm this. Among the conditions, 600 MPa for 5 min was optimal for overall quality, while 600 MPa for 10 min ensured maximal microbial inactivation. During digestion, catechins, total phenolic content, and antioxidant activity (DPPH, FRAP) decreased significantly (p < 0.05) but retained >70 %, demonstrating satisfactory stability. Overall, HPP is an effective method to maintain both the nutritional quality and microbial safety of cold-brewed green tea.