Evaluation of the Bioactivity and Effects on Cell Viability of Green Tea Residue Extracts

This study compared the physicochemical properties, physiological activities, and the effect on cell viability of green tea residue (GTR) extract with green tea (GT) and confirmed the potential of GTR as a functional food material. Significant differences were observed in the physicochemical properties between the GTR and GT extracts. The pH was higher in GTR, while the salinity and sweetness were higher in GT compared to GTR. In terms of color, the L and a values were higher in GTR than in GT, whereas the b and ΔE values were significantly higher in GT compared to GTR. Although GTR had lower total polyphenol and flavonoid contents than GT, the contents of GTR showed a gradual increase as the concentrations increased. A comparison of the antioxidant activities of GTR and GT revealed GTR to have similar DPPH and ABTS radical scavenging activities to GT at concentrations of 50, 75, and 100 mg/ml. The reducing power and lipase inhibitory activities of GTR were lower than those of GT, but GTR exhibited higher SOD-like activity at all concentrations than GT. In addition, GTR showed higher cell viability of Raw 264.7 at all concentrations than GT. These results provide fundamental information on using GTR as a functional food material and suggest that recycling food waste can contribute to sustainable resource development.