Investigation on extraction of oleoresin from ginger (Zingiber officinale Roscoe) and Its antioxidant properties

Abstract

Ginger oleoresin production has become an issue of interest nowadays due to a wide range of applications in food and pharmaceutical industries. In this study, several processing parameters which are considered to affect the performance of Randall method, solvent type, particle size and extraction time, were investigated. The yield of ginger oleoresin was then reported. The antioxidant activity of the extracted products was examined using the free DPPH scavenging method in comparison with standard ascorbic acid. Due to the lack of standards for HPLC performance, instead of ginger oleoresin, ginger essential oil was utilized for chemical analysis by GC-MS and all the substances present in the essential oil were identified. Based on the results, the two parameters, type of solvent and particle size, significantly affected the total yield. Ground ginger produced higher yield of oleoresin compared to hand-cut ginger in both cases of extraction with ethanol and methanol. Methanol, moreover, serves as a better solvent for ginger oleoresin extraction. The effect of extraction time is inappreciable on the extraction. The antioxidant activity of the ginger extracts, nonetheless, reached to 63% at the concentration of 80 μg/ml and was weaker than that of the ascorbic acid (84% at the same concentration). Keywords: Ginger, oleoresin extraction, Zingiber officinale Roscoe, antioxidant.