Impact of processing and storage on protein digestibility and bioavailability of legumes

The digestibility and bioavailability of plant protein are the key factors for meeting human nutritional needs and particularly when looking for alternatives for animal-based proteins. Legumes have great nutritional value, containing rich sources of proteins, carbohydrates, fibres, and other bioactive compounds. However, some antinutritional compounds presenting in legumes are found to adversely influence protein bioavailability and digestibility. Several food processing methods like soaking, dehulling, cooking, extrusion, enzymatic hydrolysis, fermentation, and germination have been proven to generally enhance the protein quality and lower the levels of antinutritional factors, increasing protein digestibility. However, due to the differences in legume types and applied methods, it is hard to conclude which particular processing method is the best for a specific legume type. The ways of accurately determining and improving the digestibility of legume-derived protein are still a scientific challenge, which may be solved by innovative or combined existing processing technologies. Storage of legumes may reduce their protein content due to the changes in proteolytic enzyme activity and decrease protein solubility and thermal stability caused by the reduction in pH levels within the tissues, which could be a pointer of legumes hard-to-cook defects.