Physicochemical evaluation of okra residue obtained after pectin extraction

Abstract

This study aimed to evaluate the physicochemical properties of okra residue obtained after pectin extraction from three okra genotypes (Asha, Balabi, and Agbagoma). The okra residue was oven-dried. Proximate analysis and functional properties were determined using standard AOAC methods, whereas mineral content was determined using atomic absorption spectroscopy. Phenolics and antioxidant capacity were determined using the Folin-Ciocalteu and DPPH methods. The okra pectin extraction residues were rich in carbohydrates (70.0–71.7%) and ash (19.55–21.9%), but had relatively low proteins (0.87–3.62%) and moisture (4.71–5.94%) contents. The okra residue samples had high potassium (8.59–9.27 mg/100 g) and sodium (.380–3.93 mg/100 g) contents. The solubility index for the varieties ranged from 18% to 25%, whiles swelling power ranged from 8% (Balabi) to 10% (Asha). The pectin extraction by-products showed high water absorption (546% to 617%) and oil absorption (216% to 318%) capacities. Residues from all okra genotypes demonstrated antioxidant activity (7.13–15.15%) and contained varied amounts of phenolic compounds (13.85–33.58 mg GAE/100 g). The results showed that okra residue obtained after pectin extraction has high nutritive and functional values, and could be exploited for other economic utilization instead of discarded as waste.