Phaseolins are one of the major types of storage proteins, the 7S globulins, of common beans, Phaseolus vulgaris. They accumulate in the seed cotyledons and serve as nitrogen reserves mobilized during germination. In food science and nutrition, phaseolins are significant as the principal proteins determining the nutritional quality of beans: they are relatively low in sulfur-containing amino acids, which limits their biological value unless complemented with cereal proteins. Processing such as soaking and cooking denatures phaseolins, improving digestibility and inactivating lectins and trypsin inhibitors present in raw beans. Understanding phaseolin composition helps breeders and processors improve bean protein quality for human diets.