Nutritional and antinutritional evaluation of indigenous Ethiopian Okra (<i>Abelmoschus esculentus</i>) seed accessions

Abstract

Okra, of high nutritional potential, is one of the underutilized indigenous vegetables in Ethiopia. A food based-intervention specifically dietary diversification is an affordable and sustainable strategy to meet the demand of adequate food supply and population growth. One way of ensuring dietary diversity is to search and promote underutilized indigenous plant species such as okra. Therefore, the objective of this study was to determine nutritional and anti-nutritional factors content of the seeds of eight okra accessions (OPA#1, OPA#2, OPA#3, OPA#4, OPA#5, OPA#6, OPA#7 and OPA#8) grown at Assosa Agricultural Research Center in Benishangul Gumuz region, Ethiopia. Molar ratios of the seeds were also calculated and  compared to the critical values to predict the mineral bioavailability. All the analyses were conducted using official standard procedures and grade standard reagents. The results of this study revealed that the proximate composition (g/100 g) of the seed accessions varied significantly (P<0.05) and had respective ranges for moisture content 9.27-12.70, crude protein 22.51-38.09, crude fat 18.64-36.84, crude fibre 1.94-5.96, crude ash 4.53-6.05, utilizable carbohydrate 18.69-37.77 and metabolisable energy  324.88-423.84 kcal/100g. The mineral composition (mg/100g) also varied significantly (P<0.05) with range of calcium 66.37 to 103.66, iron 8.33 to 20.29, potassium 90.00 to 187.92, zinc 3.92 to 6.42, phosphorus 16.94 to 1497.23 and sodium 15.06 to 27.81. The seeds of accession of OPA#6 contained high amounts of crude protein and fat, whereas OPA#8 was high in calcium, iron and potassium. The range of phytate, tannin and oxalate content (mg/100g) of the seed of okra accessions ranged from 0.39 to 0.46, 0.71 to 3.78, 0.74 to 0.75, respectively. The calculated molar ratios of  phytate:calcium, phytate:iron, phytate:zinc, oxalate:calcium and  phytate*calcium/zinc were 0.0025 to 0.0037, 0.0017 to 0.0041, 0.0063 to 0.106, 0.0020 to 0.0051 and 0.0140 to 0.0175, respectively, below the critical value, indicating high bioavailability of calcium, iron and zinc in all accessions. The results of this study revealed that seeds of okra contain appreciable amounts of essential nutrients and are low in  anti-nutrient content implying high mineral bioavailability. Hence, increasing the production and consumption of these nutrient rich  underutilized okra seeds could help in food fortification, dietary diversification and alleviation of problems associated with malnutrition in the country.

Key words: Okra, Seed, Accession, Proximate composition, Minerals,  Anti-nutritional factors