Extraction methods, physiological activities and high value applications of tea residue and its active components: a review

Tea is a traditional plant beverage originating from China as one of the most popular beverages worldwide, which has been an important companion in modern society. Nevertheless, as the waste after tea processing, tea residues from agriculture, industry and kitchen waste are discarded in large quantities, resulting in waste of resources and environmental pollution. In recent years, the comprehensive utilization of tea residue resources has attracted people's attention. The bioactive components remaining in tea residues demonstrate a variety of health benefits and can be recycled using advanced extraction processes. Furthermore, researchers have been devoted to converting tea residues into derivatives such as biosorbents, agricultural compost, and animal feeds through thermochemical techniques and biotechnology. This review summarized the chemical composition and physiological activities of bioactive components from tea residue. The extraction methods of bioactive components in tea residue were elucidated and the main high-value applications of tea residues were proposed. On this basis, the utilization of tea residues can be developed from a single way to a multi-channel or cascade way to improve its economic efficiency. Novel applications of tea residues in different fields, including food development, environmental remediation, energy production and composite materials, are of far-reaching significance. This review aims to provide new insights into developing the utilization of tea residue using a comprehensive strategy and exploring the mechanism of active components from tea residue on human health and their potential applications in different areas.HighlightsThe composition and function of tea residue active components were introduced.The extraction methods of active components from tea residue were proposed.The main high-value applications of tea residues were summarized.The current limitations and future directions of tea residue utilization were concluded.