Implications of hydration depletion in the in vitro starch digestibility of white bread crumb and crust

- The efficacy of decreasing dough hydration to improve bread digestibility was studied.
- Bread crust contained significantly higher slowly digestible starch than crumb.
- A hydration depletion did not prevent the starch in the crumb from gelatinization.
- Gelatinization of crust samples was reduced with a depletion in the dough hydration.
- Lower dough hydration significantly increased the SDS in crumb and crust.

The objective of this study was to provide understanding about the efficacy of decreasing dough hydration to slow down starch digestibility in white bread. Breads were made with 45 (low hydration bread, LHB), 60 (intermediate hydration bread, IHB) and 75% (high hydration bread, HHB) water (flour basis). A hydration depletion down to 45%, which is close to the minimum hydration found in commercially available white bread, did not prevent the starch in the crumb from complete gelatinization. However, LHB and IHB crumbs were more resistant to physical breakdown during in vitro digestion than HHB crumbs, resulting in a 96.81% increase of slowly digestible starch (SDS) from 75 to 45% dough hydration. The degree of gelatinization in crust samples was significantly reduced with a depletion in the dough hydration, ranging from 29.90 to 44.36%, which led to an increase of SDS from 7.41 in HHB to 13.78% in LHB (bread basis).