Characterization of the baking-induced changes in starch molecular and crystalline structures in sugar-snap cookies

•Baking-induced changes in starch molecular and crystalline structures are examined.•Baking decreases average sizes of both amylopectin and amylose molecules.•Baking slightly decreases the degree of branching of starch.•Baking also causes the loss of starch crystallinity.•Baking disrupts the periodic lamellar structure. This study aims to understand the starch molecular structural changes from baking sugar-snap cookies. Changes in the whole-molecule size distribution and chain-length distribution of the parent wheat flour and from final cookie products were measured by size-exclusion chromatography with and without enzymatic debranching, and the results fitted by two biosynthesis-based models. Fraction crystallinity was also analyzed. After cooking, there was a significant decrease in average molecular sizes of amylopectin and in the average lengths of amylose chains, and some starch granules lost birefringence. However, the chain-length distributions of amylopectin showed no noticeable difference, resulting in little change in relative crystallinity and gelatinization temperatures. Both the short-range ordered structure and the periodic lamellar structure were disrupted. This study provides new insight into starch structural changes in sugar-snap cookies after baking, which play an important role in determining final cookie quality. For example, a decrease in size of amylose chains influences cookie sensory properties, and thus can be used as an additional tool for choice of grains.