Antioxidant Capacity of Lignin From Green Tea Waste

The antioxidant capacity of lignin from used green tea leaves was evaluated by measuring its effects on the autoxidation of linoleic acid. Autoxidation of linoleic acid was reduced by 50% in the presence of tea leaf lignin. This effect was weaker than that of α-tocopherol and t-butylhydroxyanisole. However, lignin enhanced the antioxidant effects of α-tocopherol, epigallocatechin gallate or acetone extracts of used tea leaves, with the antioxidant activity of lignin + acetone extracts of used tea leaves being nearly equivalent to that of α-tocopherol and t-butylhydroxyanisole. PRACTICAL APPLICATIONS The agricultural industry generates large amounts of botanical food by-products, including used tea leaves, most of which are discarded. To determine whether lignin extracted from used green tea leaves has a practical application, we measured its effect on the autoxidation of linoleic acid, a model for the oxidation of fats. We found that lignin contained in used green tea leaves has an antioxidant effect, suggesting that used tea leaves in industrial waste may have potential applications as antioxidants for food oils and fats.