Impact of Processing and Genetic Variation on Protein Quality and Protease Inhibitor Activity in Chickpea and Dry Bean Germplasm

Dry bean consumption in the United States remains low, and improving their appeal requires understanding how genetics and processing affect protein quality and antinutritional factors. This study examined how genotype and processing influence protein composition, in vitro digestibility, and protease inhibitor activity in six dry bean genotypes and one Kabuli chickpea. Chickpea showed the highest digestibility, and microwaving, with or without dehulling, consistently improved protein quality. In raw flours, trypsin inhibitor activity ranged from 14 to 28 units. Microwaving eliminated trypsin inhibitors and reduced chymotrypsin inhibitors by 53–86%, while roasting only partially reduced trypsin inhibitors and increased chymotrypsin inhibitors. Ethanol extraction enriched antinutritional proteins, including α-amylase inhibitor, trypsin/chymotrypsin inhibitors, and lectin, confirmed by immunoblotting and mass spectrometry. Amino acid profiles were similar across genotypes, though sulfur amino acids remained low. Overall, microwaving and 35% ethanol treatment effectively reduced antinutritional factors in bean flours.