ANTIOXIDANT ACTIVITY, GLYCEMIC INDEX AND GLYCEMIC LOAD OF BOILED AND ROASTED COCOYAM (Xanthosoma mafaffa Schott) TUBER

Abstract

Xanthosoma mafaffa Schott (XMS) is an underutilized cocoyam that is relatively rich in food nutrients and antioxidant constituents. However, information on the values of glycemic index (GI) and the glycemic load (GL) of XMS is limited. Thus, this study was undertaking to contribute information on antioxidant activity and nutritional data of GI and GL values using boiled and roasted XMS tuber. Anthropometric measurements, GI, GL and antioxidant constituents were determined according to standard methods. Results showed variations in the tested parameters. Antioxidant constituents varied for carotenoids (14.33 to 49.08 mg/100gfw), total polyphenols (122.02 to 159.45 mgGAE/100gfw), total flavonoids (62.05 to 161.32 mgQE/100gfw), ascorbic acid (2.04 to 6.17 mg/100gfw) and tocopherol (1.31 to 2.63 mg/100gfw). Antioxidant activity assayed by DPPH, ABTS and FRAP ranged from 14.21 to 36.73%, 11.28 to 77.15 µmTE/100gfw and 6.03 to 19.36 mgTE/gfw. Glycemic index of standard food (glucose) and processed Xanthosoma maffafa Schott showed variance in the glycemic response (GR) from 4.17 to 4.53 mmol/L at 0 min fasting blood sugar, 4.50 to 6.83 mmol/L at 15 min, 4.60 to 7.53 mmol/L at 30 min, 4.20 to 8.37 mmol/L at 60 min, 4.27 to 5.90 mmol/L at 90 min and 4.27 to 5.77 mmol/L at 120 min post feeding intervals. In general, GI of boiled XMS (91.30 mmol/L) was higher than the roasted XMS (68.69 mmol/L) meal. With high antioxidant compounds, strong antioxidant activity, and a medium GI of roasted Xanthosoma maffafa Schott meal, it can act as a functional food to scavenge free radicals, prevent degenerative disorders and boost physiological health of consumers.