Effects of Selected Food Processing Methods on Nutrient, Antinutrient and Phytochemical Composition of African Yam Bean (Sphenostylics stenocarpa)

Abstract

African Yam bean (AYB) (Sphenostylics stenocarpa) is an underutilised legume with relatively high protein. The study was carried out to assess the effects of the four different processing methods on nutrient, antinutrient and phytochemical composition of African yam bean. The processing methods employed are soaking, cooking, fermentation and germination. African yam bean (AYB10) was obtained from seed store section of Institute of Agricultural Research and Training (I.A.R&T). For soaking methods, 200g of African yam bean were cleaned, sorted and soaked for 14 hours, after which the water was drained off. For cooking methods, soaked seeds of (AYB) were cooked in a pressure pot for 2 hours (121oC). For fermentation method, cooked seeds were transferred into a local calabash lined and wrapped with banana leaves and were left for 3 days for fermentation. For germination method, clean seeds of (AYB) were spread on a tray, lined with tissue paper, distilled water was sprinkle on the seeds and kept in a dark for 3 days. Samples were taken from each of the processing methods for laboratory analysis; Proximate (moisture content, crude protein, ash, crude fibre, crude fat and carbohydrate), phytochemicals (total phenolics and flavonoids)), antinutrients (alkaloids, phytate, tannin, saponin, protease inhibitor). The data were analysed using descriptive statistics and anova at (P≤0.05). The results showed that different processing methods examined significantly reduced the antinutrient, phytochemical and nutrient composition of AYB. However, an increased in the moisture content was observed in all the processing methods. This suggests that soaking for 14hours, cooking for 2 hours at 121oC, fermentation for 72 hours and germination for 72 hours could be appropriate methods for reducing antinutrients in African yam bean which could possibly increase its utilization.