Effects of ultrafine grinding on physicochemical, functional and surface properties of ginger stem powders.

BACKGROUND Ginger stem (GS) is a by-product from ginger processing. It can not straightly be edible as a feed or food, which leads to it discarded as wastes or burned. So it is it is very important to develop the new functional products in food or feed industry due to high nutritional and medicinal values. In this paper, the structure and physicochemical properties of ginger stem (GS) powders with different sizes were evaluated after ultrafine grinding by vibrating mill. RESULT The ultrafine powders exhibited the smaller particle size and uniform distribution. The higher values in bulk density (from1.07 ± 0.06 to 1.62 ± 0.08 g/mL), oil holding capacity (from 3.427 ± 0.04 to 4.83 ± 0.03 g/mL) and repose and slide angles (from 42.33 ± 1.52 to 54.36 ± 1.15 ° and 33.62 ± 0.75 to 47.27 ± 1.34°, respectively) of ultrafine GS powders were exhibited compared with coarse powders. With reducing particle size, the solubility of ultrafine powders increased significantly (P < 0.05), while water holding and swelling capacities decreased with particle size reduce and then increased. FTIR analysis showed that the ultrafine grinding did not damage the main cellular structure of GS powder. The reduce of fiber length and particle size in GS was observed by light microscopy and scanning electron microscopy. The X-ray diffraction patterns showed that the crystallinity and intensity of peak in in superfine GS powders. CONCLUSION The study suggested that the ultrafine grinding treatments influenced the structures and physicochemical properties of GS powders, the changes would improve the effective utilization of GS in food or feed industry. This article is protected by copyright. All rights reserved.