Particle size of ginseng (Panax ginseng Meyer) insoluble dietary fiber and its effect on physicochemical properties and antioxidant activities

Dietary fibers (DFs) and associated phytochemicals in ginseng species are known to provide various functional and health benefits. The incorporation of ginseng insoluble dietary fiber (IDF) in food products often result in undesirable physicochemical properties. Thus, to overcome such demerits, micronization of IDF has been considered. This study investigated the effect of particle size on the physicochemical properties, antioxidant activities, structure and thermal analysis of ginseng IDF. Micronized IDF powder with median particle diameter of 15.83 mu m was produced through fine grinding. Reduction of ginseng IDF resulted in increased brightness, water holding capacity and solubility. Decreasing particle sizes also lowered bulk, tapped density, Carr index and Hausner ratio. Reduction of particle size caused greater extractability of mineral and phenolic content and thereby increasing the DPPH radical scavenging activity and ferric reducing antioxidant power. Increased polyphenol extraction with smaller particle size also lowered the mice erythrocytes hemolysis percentage while the hemolysis inhibition rate was increased. Particle size also influenced the thermal stability of ginseng IDF powders. FTIR spectra revealed lack of impact on the major phenolic structures due to superfine grinding. Hence,micronized ginseng IDF powders with improved physicochemical properties and antioxidant activities possess the potential to be used in food and pharmaceutical industries.