Effect of superfine grinding on properties of ginger powder

The superfine grinding could produce a narrow and uniform particle size distribution in dry ginger. The physical-chemical properties of five types of ginger powders with particles size of 300, 149, 74, 37 and 8.34 mu m were investigated. The size was smaller for ginger powders, greater for the surface area (from 0.331 to 1.320 m(2)/g) and bulk density (from 0.3069 to 0.3426 g/ml) and smaller for the angle of repose (from 51.50 degrees to 46.33 degrees) and slide (from 45.80 degrees to 39.50 degrees). The values of water absorption index (WAI), water solubility index (WSI) and protein content significantly increased with decreasing the size of ginger particles (p < 0.05). Interestingly, the values of WAI, WSI and protein content of ginger powder with a particle size of 8.34 mu m during soaking reached 0.52 g/g, 33.70% and 84.93% for 60 min, respectively. SEM observations revealed the shape and surface morphology of five types of ginger powders. (C) 2008 Elsevier Ltd. All rights reserved.