Changes in Physical and Antioxidant Properties of Nanostructured Zingiber officinale (Ginger) Rhizome as Affected by Milling Time

In this study, Zingiber officinale (ginger) rhizome nanoparticles were prepared using a planetary ball milling process and the effect of prolong milling time up to 8 hours on the physical and antioxidant properties has been investigated. The particle size was successfully reduced to 222.3nm after 4 hours of milling process but agglomerated nanoparticles were observed for sample that was continuously milled. Sample milled for 4 hours showed higher Total Phenolic Content (TPC) (356.06 mgGAE/g extract) as well as Total Flavonoid Content (TFC) whereas lowest value shown by sample milled for 8 hours. The inhibition of DPPH reached up to 60% for all tested nanostructured ginger except very low percent of inhibitory shown by sample milled for 6 hours. The IC50 concentration for DPPH inhibition was 800ppm for sample milled for 2 hours, 400ppm for 4 hours and1000ppm for sample milled for 8 hours. However sample milled for 8 hours showed significantly (p<0.05) greater Ferric Reducing Antioxidant Power (FRAP) among other tested samples.