Abstract
Starch is typically a mixture of essentially linear amylose and highly branched amylopectin. The difference is in the nature of the covalent bonding, with multiple branch points emanating from 1–6 glycosidic linkages of amylopectin. Equally important as the chemical structure is the physical structure: single helices and double helices exist and may be the basis for crystallinity. Starch chemical structure has been modulated through breeding: high-amylose maize starch is well studied with respect to its potential to influence health. Its altered chemical structure leads to differences in the physical structure as well. Physical treatments can also lead to altered physical structure. Modulation of chemical and/or physical structures may influence health by altering the rate and extent of starch digestion in the small intestine. Undigested starch (resistant starch) reaches the large intestine where it is fermented to potentially beneficial microbial by-products that are absorbed there.