Extrusion of hard to cook bean flour: Biochemical characteristics and functional properties

Beans are an important source of protein, starch, vitamins, and minerals. However, the presence of antinutritional factors and the development of hard-to-cook grains due to storage in high humidity (>75%) and high temperatures (30-40 °C) reduce the nutritional value and acceptance of these grains, causing significant losses. An alternative for the use of hardened beans is extrusion. The extrusion process eliminates haemagglutination and ¿-amylase inhibitor activity, in addition to significantly reducing the content of phytic acid and trypsin inhibitors. In relation to the functional properties analysed, extrusion causes an increase in solubility and water absorption and gel formation capacity, a reduction in emulsifying capacity and emulsion stability, and eliminates the foaming capacity of extruded flours. Protein and starch digestibility is also significantly increased after extrusion. Thus, extrusion is an interesting alternative for the re-inclusion of hard beans in human food.