粒径对铁皮石斛粉多糖释放及其粉体特性影响

Effect of Particle Size on Polysaccharides Dissolution and Powder Characteristics of Dendrobium officinale Powders

为明确粒径对铁皮石斛(D. officinale)粉中多糖溶出率及其粉体特性的影响,采用中药粉碎机结合球磨仪制备了8种不同粒径的铁皮石斛粉体,研究各粉体样本的粒径分布、比表面积、多糖溶出率、粉体流动性、水合特性、表面微观结构及色差变化。结果表明,[20,200)目粉体中多糖溶出率随粒径减小总体呈上升趋势,但≥200目时溶出率逐渐下降;粉体流动性参数(休止角、滑动角和Carr’s指数)与粒径呈负相关,即粒径越小流动性越差,尤其是[200,250)目较[150,200)目粉体的流动性明显变差;水合特性(WHC、WSC和WSI)随粒径变小先升后降,拐点同样出现在200目前后;色差分析表明,粉体色度参数(L*、a*、b*和ΔE值)也是在[150,200)目与[200,250)目的变化幅度最大。上述结果主要与[200,250)目粉体的比表面积较[150,200)目显著增加(68.1%)有关。综上,[150,200)目(d50=95.6μm)的铁皮石斛粉兼具较好的粉体特性和多糖释放率,同时保证了粉体细度。本研究结果为铁皮石斛的粉体化高效加工及高值化利用提供了理论参考。

In order to clarify the effect of particle size on the dissolution rate of polysaccharides and the characteristics of Dendrobium officinale powders,eight D.officinale powders with different particle sizes were prepared through coarse grinding.and ball milling.Changes of the specific surface area,polysaccharide dissolution rate,powder flowability,hydration characteristics,surface microstructure,and color difference were investigated.Results indicated that the dissolution rate of the polysaccharide increased with the decrease of particle size in the range of[20,200)mesh.However,a reduction of dissolution rate was observed when the particle size over 200 mesh.The flowability parameters of D.officinale powder,including the angle of repose,angle of slide and Carr’s index,were negatively correlated with particle size.This indicated that the flowability of powder was getting worse with the decrease of particle sizes,especially for powders with a particle size range of[200,250)mesh compared to that of[150,200)mesh.The water holding capacity,water stable aggregates and water solubility index increased initially and then decreased as the particle size decreased,which reached a turning point at 200 mesh.The color difference analysis showed that the parameters,including L*,a*,b*andΔE,also exhibited the largest variation between the[150,200)mesh and[200,250)mesh powders.The reason could be due to the considerable increase in the specific surface area of the[200,250)mesh D.officinale powder compared to the[150,200)mesh(68.1%).In conclusion,the D.officinale powder with a mesh size of[150,200)(d 50=95.6μm)demonstrated favorable powder characteristics,release rate of polysaccharides and a fine particle size.This study provided a theoretical basis for the improvement of grinding process and the enhanced utilization of D.officinale.