Pu-erh tea-derived cellulose exhibits superior water/oil holding capacity compared to black and green tea celluloses: A comprehensive analysis

In this study, residues from black, green, and Pu-erh teas were used as raw materials to extract cellulose through alkali treatment and two-stage bleaching process. The structure and properties of the tea celluloses were compared. The yield and purity of the cellulose ranged from 6.3% to 10.1% and 75.5% to 88.9%, respectively. The celluloses exhibited a typical bundle fiber morphology and an I-type crystal structure, with the Iβ structure being the predominant allomorph. Crystallinity was highest in Pu-erh tea cellulose (54.8%), followed by black tea cellulose (52.6%), and green tea cellulose (47.4%). Green tea cellulose displayed the highest initial thermal degradation temperature, while Pu-erh tea cellulose had the lowest. Pu-erh tea cellulose showed the highest moisture absorption rate (12.6%), water holding capacity (10.1 g/g), and oil holding capacity (5.7 g/g), whereas these values were lowest in black tea cellulose. The correlation coefficient between Iβ structure content and water holding capacity is -0.90, and -1.00 with oil holding capacity. This study not only opens new pathways for the recycling of tea residues and their application in food packaging but also highlights the potential of tea-derived cellulose as an innovative material for dietary fiber resources with excellent water/oil holding capacities.