Physicochemical Composition and Antioxidant Activity of Five Gari Processed from Cassava Roots (Manihot esculenta Crantz) Harvested at Two Different Maturity Stages and Two Seasons

Abstract

Gari is a partially gelatinized roasted fermented granular white or yellowish product made from storage roots of cassava. It is consumed as fast foods in many countries across the world. Physicochemical composition, particle size, colour, and antioxidant activities of five gari (92/0326, 96/1414, IRAD4115, EN, and AD) processed from fresh storage roots harvested at 12 months after planting (MAP) and 15MAP compared to four (4) commercial gari (M1, M2, M3, and M4) were evaluated. The analytical results revealed that colour value $b^{\ast }$ and particle size varied significantly ( $p<0.05$ ) among the gari samples. Bound flavonoid contents were lower than free flavonoids (3.93 to 10.50 mgQE/100 g and 2.40 to 8.85 mgQE/100 g, respectively). Fourier transform infrared confirmed the functional groups in all gari samples. The antioxidant activity of the bound phenolics showed significantly ( $p<0.05$ ) higher DPPH scavenging ability than free phenolics (gari M2: 2.70 μgTE/g). Similarly, the bound phenolics showed significant ( $p<0.05$ ) variation of HRSA scavenging activity (0.18-35.09 μgTE/g). However, the best HRSA scavenging activity was found with bound phenolics of gari 96/1414, whereas HRSA scavenging activity was not detected in gari 92/0326, 96/1414, and AD. The value of ABTS scavenging activity of gari varied significantly ( $p<0.05$ ) from 20.60 to 30.17 μgTE/g and from 20.70 to 34.39 for free and bound phenolics, respectively, while free phenolics showed higher FRAP value (7.97 mgTE/g) than the bound phenolics (4.59 mgTE/g). Additionally, phenolics and antioxidant activities showed significantly ( $p<0.05$ ) a positive correlation. The present study has provided an insight into the physicochemical composition, bioactive compounds, and antioxidant activities of various gari processed at different season and maturity period of harvesting. It reveals that consumers of cassava gari can get health benefits apart from the nutritional values.