Physico-chemical Properties and Antioxidant Potentials of 6 New Varieties of Ginger ( Zingiber officinale )

摘要

The physico- chemical composition and antioxidant potentials of 6 new varieties of Ginger was evaluated. Analysis of the percentage phenol, oleoresin, lipid, dry matter , crude fibre and ash contents of the ginger varieties using the Association of analytical chemists methods indicated that UGII7GY25 had the highest phenolic content (5.69±0.06) while UGII 7GY5 had the least (4.69±0.16) (p<0.05). In terms of ash content, while UGI5GY3 had the highest among the varieties studied (2.6±0.44), UGII5GY6 had the least (0.7±0.02). In addition, the ash contents of UGII5GY6 and UGII 11GY11 were higher than reported values for ginger unlike the values obtained for oleoresin, lipid and crude fibre that were lower than the reported values for ginger. The ginger varieties were also observed to possess strong antioxidant activities as seen from their scavenging activities on 2,2 diphenyl-1-picrylhydrazyl (DPPH) radical and reducing power tests. Correlation analysis carried out revealed that the total phenolic content s of the ginger varieties correlated negatively with their total oleoresin contents suggesting that the oleoresin contents of the ginger varieties may not have come from their phenolic constituents and that the oleoresins present could have little contribution to the antioxidant activities of the ginger varieties. In addition, the ginger varieties were observed to contain high quantities of phenols and this may be responsible for their high antioxidant activities. Finally, UGII5GY6 and UGII 11GY11 contains higher quantities of minerals than reported values for ginger.