Enzymatic preparation and characterization of honey pomelo peel cellulose and its cellulose nanofibers

In this study, cellulose was extracted from honey pomelo peel (HPP) using the compound enzyme method and the cellulose nanofibers (CNFs) were prepared from it. The result of optimization experiment showed that the optimal extraction yield of cellulose was 36.57%. The optimal extraction scheme for cellulose was as follows: fixed pH at 4.8, temperature at 48 ℃, extraction time of 75 min, and supplemental amount of HPP powder, pectinase, hemicellulase and laccase were 10, 0.10, 0.10, 0.20 g, respectively. The cellulose samples extracted and purified from HPP contained 74.73% holocellulose, 64.98% cellulose, 59.74% α-cellulose and 366 polymerization degrees. CNFs were prepared by hydrolyzing the moistened cellulose solution with 15 U/mL cellulase at 50 ℃ for 15 h, with the average diameter and Zeta potential of 68.15 nm and −24.1 mV. The crystallinity and specific surface area of CNFs were 60.12% and 193.87 m2/g, while the hydrostatic contact angle of CNFs increased with the ultrasound time. Thermogravimetric analysis showed that both the purified cellulose and CNFs had better thermal stability. Purified cellulose and CNFs play important roles in various fields such as food, medicine, and industry.