Effects of Micronization Methods on Physicochemical Properties of Pleurotus eryngii Powders

The effects of micronization methods, such as shear pulverization, mechanical milling and jet milling, on the physicochemical properties of Pleurotus eryngii powders were investigated. Six powders from dried mushroom cap and stipe by the three grinding methods were prepared. Compared with shear pulverization and mechanical milling, jet milling effectively reduced particle size(cap14.16 μm and stipe 13.16μm) and brought about a narrow and uniform particle size distribution. Cap powders possessed higher protein(18.34 g/100 g, dry basis), fat and ash contents. With the same material(cap or stipe), powders from jet milling had higher values in specific surface area, bulk density, fluidity,water soluble index and solubility of protein and polysaccharide(p0.05), but lower values in the water holding and swelling capacities than other two processed powders. With the same grinding method, cap powders owned higher values in water soluble index, swelling capacity, bulk density, and solubility of polysaccharide than stipe powders. Under the same humidity environment, the water activity(Aw) of jet milling powder was less than the mechanical milling and shear pulverization powder, and aw of cap was less than that of stipe. The Oswin model was considered as the optimal regression equation of moisture sorption isotherms within different kinds of Pleurotus eryngii powders at 25 ℃, with the highest value of regression coefficient(0.9902~0.9943) and lowest value of relative errors.