In-vitro Comparative Antioxidant Effects and Proximate Composition of Peeled and Unpeeled Pigeon-pea (Cajanus cajan) Seed

Abstract

Background: Pigeon pea is an economical source of natural antioxidants and its use could be a means of attaining prospect in ensuring food safety. This in vitro study intends to compare the primary constituents and oxidation inhibition potentials of peeled pigeon pea (PPP) and unpeeled pigeon pea (UPP) seed. Methods: PPP and UPP samples were milled into flour and their corresponding soluble free phenolic extracts were prepared. Its flour was used to determine the proximate composition. The soluble-free phenolic extracts were used to assay for total phenols, total flavonoids, reducing property, DPPH radical scavenging ability iron-chelating ability and lipid peroxidation inhibition potential. Results: Proximate composition of peeled pigeon pea (PPP) had higher fat and carbohydrate content while the protein, fibre, ash and moisture content were higher in unpeeled pigeon pea (UPP). The phenolic constituents and reducing property of the Peeled pigeon pea was significantly (p < 0.05) higher than that of unpeeled pigeon pea with the value (12.80 mg/g >11.85 mg/g), (6.07 mg/g > 5.46 mg/g) and (7.40 > 5.62) respectively. The results showed that both PPP and UPP extracts have antioxidant potentials. However, PPP had higher nitrogen monoxide (NO) radical scavenging ability and iron (Fe) chelating ability than UPP. Contrary to this trend, UPP exhibited greater DPPH radical scavenging activity and more effective inhibition of lipid malondialdehyde (MDA), the final byproduct of lipid peroxidation. Conclusion: These findings provide additional evidence supporting the potential of pigeon pea as a natural source of antioxidants. The primary constituents, such as phenolics, flavonoids, and other bioactive compounds, are likely responsible for its remarkable antioxidant properties. This highlights its value as a functional ingredient in the food industry, promoting its application in developing health-focused food products.