Effect of natural fermentation on antinutritional factor, b-vitamins and mineral profile of Okra (<i>Abelmoschus esculentus</i>) seeds

Abstract

Okra seed from fibrous okra that cannot be easily cut with kitchen knife was fermented using the conventional traditional method of chance fermentation used for condiment production in Nigeria. Samples were taken at 24 h interval for the determination of antinutrients, B vitamins (thiamine, riboflavin and pyridoxine) and mineral profile using standard methods. Mineral and molar ratios were calculated. Fermentation substantially decreased the phytate contents by 64.98%, tannin contents by 85.10%. oxalate content by 92.85% and saponin by 2.80%. The B vitamins reduced with fermentation but as the fermentation period increased from 72 h to 120 h, all the B vitamins were increasing in quantity, thiamine by 29.32%, riboflavin by 0.9% and pyridoxine by 22.11%. K, Ca, Mg and Na were the most abundant elements in the fermented and unfermented okra seed. At the end of the fermentation period of 120 h, P, Na and Ca increased, while K and Mg reduced. The mineral ratios Ca: P, Na: K, Ca: Mg, Ca: K, Fe: Zn and the miliequivalent ratio K: (Ca + Mg) were within the required standard for their availability for absorption. [Ca][Phytate]/ [Zn] molar ratio for both the fermented and unfermented okra seed (0.0015-0.0033 mol/kg) were below 0.5mol/kg the critical value. Fermented okra seed can be used as a condiment and as food for domestic animals in order to curtail the postharvest loss of fibrous okra. However, future studies to estimate the safety of the food could be carried out since it involved micro-organisms.

Keywords: Fermentation, okra seed, B vitamins, antinutrients, minerals