Valorization of brewed tea waste into functional cello-oligosaccharides via alkaline pretreatment and...

This study investigated brewed tea waste (BTW) collected from High Mountain and Red Oolong tea leaves (HMOTL and ROTL), which were pretreated at varying temperatures and with different NaOH concentrations. Afterward, it was enzymatically decomposed into small molecules of cello oligosaccharides (OS) by using enzymes (cellulase and hemicellulase) and high-pressure processing (HPP) under different conditions. In addition to investigating the physicochemical properties of BTW lignocelluloses, this study also analyzed the composition and contents of these OS. The assessment of various Cello-OS formulations included analysis of molecular weight (MW) distributions by gel permeation chromatography (GPC) and thin-layer chromatography (TLC). This study showed that using 1% NaOH at 40 °C, followed by enzymatic hydrolysis, resulted in effective pore formation and a structured cellulose arrangement on the surface of BTW. These sequential processes degraded lignocellulosic structure and increased cellulose's crystallinity index (CrI). In addition, the treated BTWs contained xylo-triose, maltose, glucose, and possibly cellotetraose and cellopentose. Based on these findings, this study demonstrates that BTWs can be converted into small-molecule OS, positioning them as promising ingredients for functional nutraceuticals. The approach addresses the challenges posed by large volumes of biotechnological hydrolysates, enabling applications and visions aligned with the circular bioeconomy.