Valorization of green tea residues through dual carboxymethylation-homogenization treatment for improved dietary...

This study evaluated the effects of carboxymethylation (CM) and combined carboxymethylation-homogenization (CMH) on dietary fiber (DF) from green tea residues. CMH-DF exhibited a significantly higher soluble dietary fiber content (16.07%) and a lower IDF/SDF ratio (3.20) than CM-DF, indicating effective conversion of insoluble fractions. Structural analysis via SEM revealed a looser, more porous architecture in CMH-DF, while FTIR and XRD confirmed successful chemical modification and increased crystallinity. Furthermore, CMH treatment significantly enhanced functional properties, including water-holding and swelling capacities, as well as glucose and cholesterol adsorption. CMH-DF exhibited higher viscosity (0.247 Pa·s) and improved rheological behavior. Increased levels of ellagic acid (3.2-fold), catechin (2.2-fold), resveratrol (2.1-fold), and ferulic acid (2.0-fold) correlated with stronger antioxidant activities (DPPH, ABTS, and FRAP) observed for CMH-DF. These results demonstrate that carboxymethylation combined with homogenization effectively valorizes green tea residue into a multifunctional ingredient with improved techno-functional and health-promoting properties.