Optimized extraction of polyphenols from tea factory waste and cost-effective drying methods for sustainable utilization

Abstract

This study systematically addresses the significance of polyphenol extraction and preservation from factory tea waste, aiming to unlock its untapped potential by emphasizing sustainability and resource efficiency. Tea, renowned for its rich content of polyphenols and their notable antioxidant properties, serves as a reservoir of valuable organic compounds. However, in the realm of tea processing, a substantial volume of waste is generated, often subject to environmentally detrimental disposal practices. Delving into the substantial waste generated in tea processing, the research optimizes polyphenol extraction parameters using water as a solvent, establishing optimal conditions at 80 °C, 60 min, and a solid-to-liquid ratio of 1:30 (g/mL). At the optimized condition, the recorded polyphenol content was 2635.36 ± 52.07 mg GAE/L, highlighting the efficacy of the established parameters. The study validates the predicted responses of the Response Surface Methodology (RSM) model, identifies major polyphenols through LC-MS, confirms antioxidant activity via DPPH assay, and evaluates the biocompatibility of the tea waste polyphenolic extract with HEK 293 cells through MTT assay. The study employed four distinct drying methods—freeze drying, hot air over-drying, vacuum drying, and microwave drying. To preserve the quality of the TPC in the powder, optimization of drying time and temperature was undertaken. Notably, among these methods, vacuum drying at 50 °C emerged as the most cost-efficient drying option, amounting to $1.77/g of TPC powder, while concurrently maintaining a TPC value of 163.63 ± 5.43 mg GAE/L. This sustainable approach holds promise for diverse applications, including nutraceuticals, food preservation, cosmetics, and environmental remediation, aligning with global sustainability goals.