Effects of particle sizes on structural and physicochemical properties of pomelo peel powders

The structural and physicochemical properties of pomelo peel powders with different particle sizes were investigated. The MasterSizer and scanning electron microscopy observations indicated that three pomelo peel powders with different particle sizes were successfully prepared via jet milling, of which the average diameters ( d (90) ) were 53.43 ± 0.49, 27.73 ± 0.13, and 20.15 ± 0.17 µm. Fourier-transform infrared spectroscopy, X-ray diffraction, and low field nuclear magnetic resonance analysis indicated that the functional groups of pomelo peel powders were not affected by particle size; while the crystal region, proportion of immobile water ( A 22 ) and free water ( A 23 ) decreased with reduced particle size. The decrease in the proportion of immobile water and free water resulted in reduced solubility and water-holding capacity of pomelo peel powders with the smallest particle size. Our findings suggest that the desirable properties of pomelo peel powders can be designed by appropriate particle size. Practical application The study investigated the structural and physicochemical properties of pomelo peel powders with different particle sizes. The data indicated that the desirable properties of pomelo peel powders can be designed by appropriate particle size. The study may be useful for the utilization of pomelo peels as a raw food material.