Valorization of tea waste: Composition, bioactivity, extraction methods, and utilization

Abstract

Tea is the most consumed beverage worldwide and has many health effects. Although there are many different types of tea, black tea and green tea comprise 98% of total tea production in the world. Tea waste production consists of withering, crushing, fermentation, drying and finally packaging processes. All of the waste generated during this production line is called tea waste. Tea production results in a significant amount of waste that cannot be effectively used for value creation. This waste contains many different components including protein, fiber, caffeine, and polyphenols. Due to its rich composition, it can be revalorized for different purposes. In this study, the general composition and bioactive compounds of tea waste were reviewed. Despite the fact that there have been few studies on the bioactivity of tea waste, those studies have also been discussed. The extraction techniques that are used to separate the compounds in the waste are also covered. It has been indicated that these valuable compounds, which can be separated from tea wastes by extraction methods, have the potential to be used for different purposes, such as biogas production, functional foods, food additives, silages, soluble packaging materials, and adsorbents. Although there are some studies on the revalorization of tea waste, new studies on the extraction of bioactive compounds are necessary to improve its utilization potential.

Pruned tea biomass plays a significant role in functional food production: A review on characterization and comprehensive utilization of abandon‐plucked fresh tea leaves

“…Enzyme-assisted extraction facilitates the bounded bioactive components to transfer to the extraction and solvent and has the advantage of high yields over solvent extraction. For instance, tannase-assisted polyphenols extraction and cellulase-assisted carbohydrates and proteins extraction all gained increased extraction efficiency as compared to conventional solvent extraction (Baik et al, 2015;Çakmak et al, 2024). Ultrasound-assisted extraction is time-saving and more efficient than hot water extraction because the mechanical, cavitation, and thermal effects of ultrasonic waves are used to improve the penetration ability of small-molecule substances in a medium (Sanz et al, 2020).…”