Resistant and Slowly Digested Starch in Grain Products
The consumption of slowly digestible and resistant starches results in a lower glycemic response compared with rapidly digestible starch due to the slower absorption of glucose in the small intestine. Resistant starch is the portion of starch that passes undigested to the colon, where it is fermented by microbiota. Slowly digestible and resistant starches contribute to the health benefits of whole grains and whole grain products. However, resistant starch differs from traditional fibres in that it is fermented in the large bowel, producing short-chain fatty acids which are known to promote large bowel health. The formation of resistant starch is primarily dependent on the activities of specific starch synthesis enzymes. The alteration of these enzyme activities by genetic mutations has led to the production of high-amylose grain cultivars rich in resistant starch. Commercially available resistant starch can be incorporated into grain-based products. The addition of resistant starch provides an avenue to increase the fibre content of foods, with superior sensory acceptability and nutritional value compared with other fibres. The ease of incorporation of resistant starch into foods combined with the profound influence on health makes resistant starch an excellent ingredient for grain-based functional foods.