Comparative Study of the Nutrients, Anti-Nutrients and Phytochemical Properties of Two Varieties of Okra (Abelmoschus esculentus) Consumed in Southwest of Nigeria

Abstract

Okra (Abelmoschus esculentus) is a widely consumed vegetable in Nigeria that is prized for its excellent nutritional value. This study presents a comparative analysis of the nutritional, anti-nutritional, and phytochemical properties of long and short varieties of okra commonly consumed in southwestern Nigeria. Proximate composition was determined using standard AOAC methods. Calcium, iron, potassium, zinc, phosphorus, sodium, magnesium, manganese, copper and cobalt composition were quantified by Atomic Absorption Spectrophotometry. Fatty acid composition was analyzed by gas chromatography. Standard laboratory procedures were used to quantify phytochemicals and antinutrients. DPPH radical scavenging activity was assessed using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and ascorbic acid content was measured using a modified spectrophotometric method based on reduction of 2, 6-dichlorophenolindophenol (DCPIP).The short variety showed higher (p<0.05) moisture (11.20%), protein (17.10%), fat (1.70%), total ash (5.5%) and carbohydrate (63.20%) contents, while the long variety had higher (p<0.05) fibre (24.70%) contents. Mineral analysis indicated higher (p<0.05) levels of calcium, potassium, zinc, sodium and phosphorus in the short variety, whereas the long variety was slightly richer in iron and cobalt. Phytochemical screening revealed that the long variety contained higher (p<0.05) levels of saponins, flavonoids, alkaloids, terpenoids, and phenols, while the short variety had higher (p<0.05) cardiac glycoside content. Fatty acid composition varied slightly between the two, with linoleic and oleic acids being predominant in both. Anti-nutrient studies showed higher (p<0.05) oxalate content in the long variety, whereas the short variety had higher (p<0.05) levels of tannins and phytates. Additionally, the long variety exhibited greater (p<0.05) DPPH radical scavenging activity (85.43%) and higher (p<0.05) ascorbic acid content (0.09 g/100g) compared to the short variety (78.86% and 0.04 g/100g, respectively). The findings highlight distinct variations in the nutritional and phytochemical compositions of both okra varieties, particularly, in optimizing the selection of okra varieties for specific nutritional benefits or for targeted dietary interventions.