Cell wall permeability in relation to in vitro starch digestion of pea cotyledon cells

The role of cell wall permeability and rate of starch digestibility in intact cotyledon cells from four different varieties of pea seeds was studied. Pulsed-field gradient nuclear magnetic resonance (PFG NMR) coupled with light and confocal microscopy were employed to evaluate the cotyledon cells' diffusion coefficients and cell wall permeability. The cotyledon cells' diffusion coefficients and cell wall permeability followed a decreasing trend: White/yellow pea > Marrowfat pea > Maple pea > Blue pea. The varying size of internal cavities in the microstructure in the cotyledon cells, as observed by the light and confocal micrographs, may be responsible for this trend. The extent of starch hydrolysis recorded from the cotyledon cells followed the same trend of the cell wall permeability except for Blue pea cotyledon cells. Thus, indicating that the more permeable the cotyledon cell to the starch-degrading enzymes, the higher the extent of intracellular starch hydrolysis. The microstructure changes in the cotyledon cells during digestion also confirmed this observation.