Chemical cross-linking reduces in vitro starch digestibility of cooked potato parenchyma cells

Intact parenchyma cells were successfully isolated from potato tuber and chemically cross-linked with 5–12 wt% sodium trimetaphosphate/sodium tripolyphosphate for investigating the effect of cross-linking on the structural characteristics and enzyme susceptibility of starch encapsulated within the cell walls. The results indicated that both starch and cell wall polysaccharides were cross-linked, and the swelling power of starch was significantly decreased with increasing degree of cross-linking. The cross-linking reaction also significantly reduced the rate and extent of starch digestion in both intact and disrupted cells after cooking. In addition, the cell-wall barrier effect on starch digestion increased with the degree of cross-linking, due probably to that limited starch swelling and pectin solubilization during cooking process partially protected cell wall integrity and thus decreased cell wall permeability. Overall, the study suggests that chemically cross-linking of cell wall polysaccharides can slow down the in vitro starch digestion of cooked potato foods.