Nutrient composition and anti-nutritional properties of okra (Abelmoschus esculentus) calyx flour

Abstract

Purpose Calyx of okra pods is usually cut off and discarded as a waste during processing, whereas the pulp and seeds are being used. This study aims to investigate the nutrient composition and anti-nutritional properties of okra calyx flour. Design/methodology/approach Calyces from four varieties (Ex-kwadon, Solar, Chalawa and Syria) of okra pods were processed into flour. The proximate composition, mineral content, vitamin content and anti-nutritional composition of the flour samples were analysed by using standard methods. Findings There were significant differences in moisture content (p = 0.012), crude fat (p = 0.001), crude fibre (p = 0.002), carbohydrate (p = 0.002), sodium (p < 0.001), magnesium (p < 0.001), iron (p < 0.001), zinc (p = 0.006), vitamin A (p < 0.001) and vitamin C (p = 0.001) contents of okra calyx flour. The values of proximate composition ranged 8.1-8.9%, 8.4-9.0%, 14.3-15.3%, 1.4-2.1%, 16.9-18.2% and 47.1-49.4% for moisture content, ash, crude protein, crude fat, crude fibre and carbohydrate, respectively, whereas the values of mineral contents ranged 7.6-8.7 mg/100g, 35.7-41.2 mg/100g, 26.5-28.1 mg/100g, 93.2-95.8 mg/100g, 1.6-1.8 mg/100g and 5.2-5.7 mg/100g for sodium, magnesium, potassium, calcium, iron and zinc, respectively. The values of vitamin contents of okra calyx flour ranged 0.2-0.3 µg/100g, 7.1-8.9 mg/100g and 0.1-0.2 mg/100g for vitamin A, vitamin C and thiamine contents respectively. Also, there were significant differences in the values of phytate (p = 0.023), oxalate (p = 0.011) and saponin (p < 0.001) contents with the values of anti-nutritional properties ranging 1.3-1.5 mg/100g, 2.5-3.3 mg/100g, 7.4-9.7 mg/100g and 2.3-3.6 mg/100g for tannin, phytate, oxalate and saponin contents, respectively. Research limitations/implications There are scanty published works/information on proximate composition, mineral content, vitamin content and anti-nutritional composition of okra calyx flour. Practical implications The study showed that okra calyx flour could be useful in fortification/supplement of carbohydrate-based foods in food system. Originality/value Okra calyx flour comprises high crude fibre, crude protein, ash and vitamin C contents. Also, calcium is the major mineral content of okra calyx flour followed by magnesium and potassium. However, the tannin content reported higher in okra leaf flour, and okra flour is low in okra calyx flour.