Dry roller-milled yellow pea and chickpea flours with high cotyledon cell integrity reduce starch digestibility

The objectives of this study were to use dry roller milling to produce pulse flours varying in cell integrity and develop food ingredients with controlled starch digestibility. Yellow peas and chickpeas were milled into flours with coarse-, medium-, and small-sized particles (with volume-weighted mean particle sizes of ~940, 400 and 150 μm) but having essentially the same composition. These flours were analyzed for morphology, thermal properties, pasting characteristics, and in vitro starch digestibility. Raw coarse-sized flours retained more intact cotyledon cells as observed by confocal laser scanning microscopy, resulting in high resistant starch (RS) (~50%) and low rapidly digestible starch (RDS) contents. Upon cooking, the RS content decreased and the RDS content increased in all flours, but the coarse-sized yellow pea and chickpea flours still retained higher RS (~25-30%) and lower RDS contents compared with the medium- and small-sized flours. Coarse-sized flours exhibited the highest gelatinization temperatures and the lowest pasting viscosities because of intact cotyledon cells inhibiting starch swelling. These findings demonstrate that dry roller milling can be used as a scalable processing strategy to preserve cotyledon cell integrity and develop pulse ingredients with reduced starch digestibility.