Nutritional and Functional Attributes of Legumes: A Review of Processing Methods and Their Impacts

Legumes that are rich in nutrients account for approximately 20%-25% of global dietary protein, in addition to providing complex carbohydrates, dietary fiber, essential minerals, and beneficial phytochemicals. However, naturally occurring antinutritional factors (ANFs), like phytic acid, tannins, lectins, and trypsin inhibitors, impede the utilization of their nutritional value by hindering mineral absorption and protein breakdown. Processing plays a critical role in addressing these limitations by improving safety, palatability, and functionality and resulting in a wide range of food applications. This review examines the effects of both traditional and industrial processing techniques, including grinding, soaking, germination, fermentation, thermal treatments, agglomeration, and protein isolation, on the nutritional and functional characteristics in legumes. The degree of impact of these methods on legumes varies depending on the specific process and legume type. For instance, fermentation markedly diminishes phytates, tannins, and saponins by more than 60% while facilitating the production of bioactive peptides. Germination improves protein digestibility and micronutrient bioavailability, whereas soaking elevates soluble dietary fiber by as much as 33%, despite a reduction in phenolics and minerals that leached into the water. Moreover, thermal treatments effectively neutralize heat-sensitive ANFs but may reduce antioxidant capacity by 50%-95%, depending on the specific legume and processing conditions. As no single processing method could provide the desirable nutritional and functional attributes, this review proposes integrated processing strategies that balance nutrient retention against antinutrient reduction to support the development of functional legume-based food ingredients.