The impact of cellular integrity on legume macronutrient digestion across different legume types

It has been repeatedly reported that preserving cellular integrity contributes to slow down starch digestibility in legumes. However, no study has isolated and quantified this effect across several legumes. In this study the impact of cellular integrity on in vitro protein and starch digestion was studied across different legume types (black bean, chickpea, kidney bean, green lentil and yellow pea). For the first time, the amylase activity trapped by intact legume cells was quantified and used to explain differences in starch digestibility between intact legume cells. The presence of a cellular structure primarily slows down the amount of starch digested in the first 20 min of intestinal digestion (RDS), while having little to no effect on total protein or starch digestion after complete in vitro digestion. The impact of cell integrity on RDS varied across legumes. Cellular disruption increased RDS by 12% for black bean up to 44% for kidney bean. The relative increases in RDS produced by the disintegration of the cell integrity of the intact flours did not strongly correlate with the α-amylase activities measured in the intact flours. This suggests that the amylase activity trapped by the cells alone cannot explain the effect on starch digestion in intact cells or that quantification of intracellular amylase activity requires separate quantification of the amylase-cell wall interactions.