Underutilized Legumes, Oilseeds and Tubers as Sustainable Protein Sources: Processing, Fermentation, Nutritional Quality and Food Safety of Plant-Based Foods

Abstract

Global demand for protein is rising at a time when the environmental costs of animal production and the climate vulnerability of major crops are becoming more apparent. Most plant-based protein ingredients are drawn from a very small number of crops, principally soybean, pea and wheat, which leaves food systems exposed to supply shocks and neglects a large reservoir of nutritious, climate-resilient species that are grown and eaten locally, particularly in Africa and Asia, but have received little research or commercial attention. This review examines underutilized legumes (including bambara groundnut, African yam bean, pigeon pea, cowpea landraces, winged bean, lupin, grass pea and mung bean), oilseeds (including melon seed, sunflower, cottonseed and moringa) and tubers and roots (including tiger nut, cassava leaves, yam and potato) as sources of protein for plant-based foods. For each group it considers composition, protein functionality and agronomic value, and it then reviews the processing technologies, including dehulling, soaking, germination, cooking, protein extraction and hydrolysis, that improve their nutritional and functional properties. Particular attention is given to fermentation, both the indigenous alkaline and lactic fermentations that have long been used to transform these crops in West Africa and Southeast Asia and the controlled, starter-culture-driven fermentations that can bring those traditions into modern food manufacture. The review then evaluates nutritional quality, including amino acid adequacy, digestibility and bioactive peptides, and food safety hazards, including natural toxicants such as cyanogenic glycosides, β-ODAP and gossypol, allergens, mycotoxins and microbial pathogens. It concludes that underutilized crops can make a significant contribution to sustainable protein supply, but that realising this potential requires investment in breeding, processing infrastructure, controlled fermentation, food safety assurance and the regulatory recognition of traditional foods.