Effect of Cooking Time on Some Anti-Nutritional Compounds and Some Organic Acids of Bulbils Flour from Yam (Dioscorea bulbifera)

Abstract

Background: Dioscorea bulbifera bulbils are rich in nutrients but contain substantial levels of antinutritional factors that hinder mineral bioavailability and digestibility. Optimizing cooking time is therefore crucial to effectively reduce these compounds while preserving important organic acids and overall food quality. Aims: To assess the baking impact on antinutritional factors and the organic acid content of flours produced from the bulbils of the yam (Dioscorea bulbifera) cultivar «Dougou-won» with a view to determining whether this cooking method is suitable for human consumption. Study Design: Analysis of Variance (ANOVA) is employed in this work. Place and Duration of Study: Department of Food Science and Technology, Laboratory of Biocatalysis and Bioprocessing, University Nangui Abrogoua, Abidjan, Côte d’Ivoire, during the period from June 2015 to August 2016. Methodology: The bulbils of yam (Dioscorea bulbifera) used in this study are harvested at physiological maturity, six months after planting in a field in Agou, a village in south-eastern Côte d’Ivoire. After harvesting, the samples are immediately transported to the Biocatalysis and Bioprocesses Laboratory. 2 kilograms of this bulbils are washed in drinking water to remove any impurities, then peeled using a stainless steel knife. The peeled samples are rinsed twice in clean water and cut into pieces weighing approximately 50 grams. They are then baked at 100°C for periods of 10 minutes, 20 minutes and 30 minutes respectively. The hot samples are removed from the oven and left to cool in the open air for 25 minutes. They were then dried at 45°C in a forced-air oven (MEMMERT) for 48 hours. After removal from the forced-air oven, the dried samples are ground into various fine flours (FF10, FF20, FF30 means flours from bulbils of yam (Dioscorea bulbifera) baked at 100°C during 10, 20 and 30 minutes respectively). These different flours are obtained after sieving using a 250 micrometers mesh sieve. Finally the antinutritional factors and organic acids levels of flours from bulbils yam are analyzed using standard methods. Results: While the organic acid content of bulbil flours increases, the baking after 30 minutes decreases significantly (P≤ 0.05) the phenolic compound levels and antinutritional factors including total phenolic compounds (551±2,65 to 536±1,75 mg/100g of dry matters), total oxalates (317±1 to 312±2 mg/100g of dry matters), phytates (466±1,73 to 448±1,73 mg/100g of dry matters) and tannins (64±1 to 58±1 mg/100g of dry matters). However, the levels of the antinutritional factors studied remained below established lethal thresholds, posing no risk to consumers. Conclusion Consequently, baking appears to be a suitable cooking method for the safe consumption of bulbils flour from yam (Dioscorea bulbifera) cultivar «Dougou-won».