Antioxidant Properties of Different Ginger Extracts (Zingiber officinale)

Chua, Thong Shuen (2021) Antioxidant Properties of Different Ginger Extracts (Zingiber officinale). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Ginger (Zingiber Officinale Roscoe) is one of the most widely used herbs that belongs to the family Zingiberaceae and contains several bioactive constituents and possesses pharmacological properties as antioxidant, antimicrobial, anti-carcinogenic and antiinflammatory activities. Although the antioxidant activity of various ginger species has long been established, however this provides evidence that ginger’ antioxidant activity is due to high polyphenolic content, which varies depending on the extraction parameters. The extraction was performed through solvent extraction using ethanol as the solvent at various temperature (40˚C and 70˚C) and time (1 hour and 4 hours). The crude ginger extracts were then analyzed for DPPH, TPC, TFC, ABTS and FRAP assays. The results demonstrated that all types of ginger extracts had significant differences (p<0.05) in the antioxidant activity in different extraction parameters. The highest TPC and FRAP values were 28.74 ± 0.20 mg GAE/100g and 81.24 ± 2.71 mg FE/100g, respectively, found in LN5 401 (ginger of 5-month old ginger powder at 40˚C for 1 hour). In contrast, ES 704 (China local ginger powder at 70˚C for 4 hours) showed the highest DPPH radical scavenging capacity (0.652 ± 0.01 mg AAE/100g). On the other hand, LN9 401 (ginger of 9-month old ginger powder at 40˚C for 1 hour) was found to have the highest flavonoid compounds (226.60 ± 20.75 mg QE/100g) while LN9 704 (ginger of 9-month old ginger powder at 70˚C for 4 hours) had the highest ABTS value (2.86 ± 0.33 mg TE/100g). Overall, ginger extracts showed the highest antioxidant activity in solvent extraction at 40˚C for 1 hour.