The Roles of a Native Starch and a Resistant Dextrin in Texture Improvement and Low Glycemic Index of Biscuits

Abstract

Low-GI biscuits are commonly produced using whole-grain flour, bran, or soluble dietary fibers, giving an undesirable texture. New low-GI biscuits containing dietary fibers and with improved palatability were formulated by substituting 60% of wheat flour (WF) with a native starch (ST) and 15% of WF with a resistant dextrin (RD), a source of dietary fibers. The botanical source of ST was common buckwheat (Fagopyrum esculentum Moench). Biscuits were also made with a single substitution by ST or by RD at the same level for comparison. The firmness of the biscuits was increased with the single substitution by RD due to its small average molecular size and high hygroscopicity, while it was decreased with the single substitution by ST. The double substitution by ST and RD not only produced the texture with the lowest firmness and brittleness, but also led to the lowest in vitro starch digestion rate and total starch digestibility. The human trial confirmed that the biscuits with the double substitution had a low GI of 47. The results indicated the additive or synergistic effects of ST and RD on the properties of the biscuits, demonstrating that low-GI biscuits can be produced with a substantial dietary fiber content without jeopardizing their palatability.