超微粉碎对桑叶粉理化性质的影响

为拓展超微粉碎技术在食品添加剂和药品开发中应用，以桑叶为原料，分别对桑叶粗粉进行干法超微粉碎2 、4、6、8 h，得到4种不同粒径大小的桑叶超微粉，并对桑叶粗粉与4种超微粉的理化性质进行比较。研究结果表明，超微粉碎能明显减小桑叶粗粉的颗粒粒径（P＜0.05），随着超微粉碎时间的增加，超微粉的粒径减小，粉体的粒径分布范围变窄，比表面积和体积密度显著增加（P＜0.05），休止角、滑角和膨胀性显著降低（P＜0.05），水溶性/持水力、持油力、蛋白质的水溶性和多糖的水溶解性均有不同程度的增加，但多酚含量变化不显著（P＞0.05）。扫描电镜结果显示，粗粉经超微粉碎后，其颗粒呈零散的分布形态。说明超微粉碎可改善桑叶粉的部分理化性质，可将这些性质应用于食品添加剂和常规食品开发与加工中。所得研究结果将为超微粉碎技术在桑叶食品中工业化应用提供数据支持和理论依据。

Effect of superfine grinding on physicochemical properties of mulberry leaf powder

Abstract: Superfine grinding technology is a type of food processing that used to produce powders with outstanding properties such as high solubility, dispersion, adsorption, chemical reactivity and fluidity. In order to expand the application of the superfine grinding technology in food additive and pharmaceutical industries, the physicochemical properties of mulberry leaf micro-powders were investigated. Four types of mulberry leaf micronized powders were prepared by pulverizing its coarse through superfine grinding for different periods of time (2, 4, 6 and 8 h). The physicochemical properties of the micronized powders and the coarse powder were then compared and investigated. The results showed that superfine grinding could effectively pulverize coarse powder to different micro-sizes. With increased superfine grinding time, the particle size significantly decreased (P<0.05). Furthermore, with narrowed particle size distribution, the specific surface area and bulk density significantly increased (P<0.05); the angle of repose and slide and swelling capacity significantly decreased (P<0.05); and water and oil holding capacity, protein and polysaccharide solubility and water solubility index improved to different extents. These indexes were tightly dependent on particle size with absolute coefficients beyond 0.6156. However, no significant difference was observed in flavonoid content among mulberry leaf particles (P>0.05). Scanning electron micrography observations revealed the shape morphology of the fragmented mulberry granules. The physicochemical properties of micro-powder D milled at 8 h were more satisfying than micro-powders A, B, and C (milled at 2, 4 and 6 h, respectively). These results suggested that superfine grinding could improve some physicochemical properties of mulberry leaf powder, thereby enabling its applications as a functional food additive and food product, as well as a material for the pharmaceutical industry.