Evaluation of Nutritional Composition and the Impact of Cooking and Soaking on Selected Underutilized Nigerian Legumes (Velvet and Lima Beans)

Abstract

Underutilized legumes velvet beans (Mucuna pruriens) and lima beans (Phaseolus lunatus) were assessed for nutritional composition and the effects of traditional processing treatments involving 24-hour soaking and 60-minute cooking, using proximate analysis and Gas Chromatography-Mass Spectrometry (GC-MS). Raw velvet beans contained significantly higher crude protein than lima beans, comparable to cowpeas. Processing reduced protein content from 9-29 % across legumes but led to increases in carbohydrate concentration. The analysis through GC-MS showed that L-DOPA (in velvet beans) neurotoxin decreased by 66.42% and the complete elimination of juglone, a protease inhibitor in lima beans. Although conventional processing methods worked well to lower anti-nutritional factors, they also lowered protein retention, showing an important tradeoff between detoxification and nutrient retention. This study highlights the value of using underutilized legumes like velvet beans which have a protein content similar to cowpeas, to diversify sources of protein in areas of food insecurity. By advocating for optimized processing strategies that prioritize both safety and nutritional quality, these findings contribute to sustainable dietary solutions aligned with global goals to combat malnutrition and promote resilient food systems.