Improvement of Functional Properties of Cellulose from Xuehua Pear Pomace by Steam Explosion Pretreatment

This study aimed to evaluate the effect of steam explosion (SE) pretreatment on the physicochemical (particle size, zeta potential, functional groups and thermal stability) and functional (water-holding capacity (WHC); oil-holding capacity (OHC); glucose adsorption capacity (GAC); and cholesterol adsorption capacity (CAC) properties of microcrystalline cellulose (MCC), acid-extracted cellulose nanocrystal (ACNC) and enzymatically extracted cellulose nanocrystal (ECNC) from pear pomace. Results showed that the particle size of cellulose nanocrystal (CNC) prepared with SE at steam pressure levels of 0.6–0.9 MPa was the smallest (140.12 nm on average). The surface of SE treated pear pomace cellulose was negatively charged and SE reduced the absolute potential value. MCC had higher absolute potential value than CNC. Fourier transform infrared (FTIR) spectroscopy showed that all pear pomace cellulose samples had the molecular structural characteristics of cellulose and the structure of CNC was not damaged. The best thermal stability of MCC and the best OHC of ACNC were obtained by SE treatment at 0.9 MPa and 0.3–0.6 MPa, respectively. SE at 0.6 and 0.3 MPa resulted in the best GAC and CAC of ACNC, respectively. Overall, the optimum conditions for the preparation of CNC from pear pomace with good properties were obtained as SE pretreatment at steam pressure of 0.3–0.6 MPa followed by sulfuric acid (64%) treatment for 50 min. The findings of this study lay a theoretical foundation for the high-value utilization of pear pomace.