Changes in odor characteristics of pulse protein isolates from germinated chickpea, lentil, and yellow pea: Role of lipoxygenase and free radicals

Abstract

In this study, pulse protein isolates (PPIs) were extracted from 0, 1, 3, and 5 days germinated chickpea, lentil, and yellow pea flours by alkaline extraction–isoelectric precipitation method. The germination time had negligible impact on the proximate composition of PPIs. In total, 67 volatiles in PPIs were identified via HS-SPME–GC–MS/O. Among all the identified volatile components, seven of them, including hexanal (11), (E)-2-octen-1-ol (7), (E,Z)-2,6-nonadienal (17), 3-octen-2-one (33), 3,5-octadien-2-one (34), 2-methoxy-3-isopropylpyrazine (56), and 2-methoxy-3-(1-methylpropyl)pyrazine (57), contributed to the beany-related odor of PPIs but much less than that in raw flours. However, the overall beany-related odor of PPIs increased when the germination time exceeded 1 day. Both the activity of lipoxygenase and the free radical populations in PPIs were positively related to the overall beany-related odor. Our findings are crucial for the preparation of germinated pulse proteins with improved functionality but without increasing undesirable odor.