Effect of Steam Explosion Pretreatment on Citrus Peel Pectin Structure and Emulsification Stability

In order to investigate the effects of steam explosion (SE) pretreatment on the structure and emulsification stability of citrus peel pectin (CP), different pressures (0.3 MPa and 0.45 MPa, 3 min) were applied to treat citrus peels. The structural characteristics of CP were analyzed by high-performance liquid chromatography (HPLC), Fourier-transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance spectroscopy (NMR). Meanwhile, emulsification stability of CP were assessed through surface interface tensiometer, laser particle sizer and confocal laser scanning microscopy (CLSM). The results revealed that the extraction yield of CP was significantly increased (P<0.05) after SE-0.3 MPa treatment from 7.59% to 21.17%. Moreover, molecular weight (Mw) of CP was reduced from 318.41 kDa to 114.22 kDa (0.3 MPa) and 48.26 kDa (0.45 MPa), respectively. Additionally, emulsion droplet size was significantly decreased (P<0.05) from 9.31 μm to 5.43 μm after SE-0.3 MPa treatment. No significant creaming, phase separation and increase of droplet size were observed in emulsion after storage at 25 ℃ for 21 days. This study provides a theoretical reference for the application of SE technology in the comprehensive utilization of citrus by-products.