Sweet potato microstructure, starch digestion, and glycemic index

Sweet potatoes are an important source of starch-based food in the Asian diet because of their superior nutritional and functional properties. The main carbohydrate of sweet potato is starch, which accounts for nearly 80% of the dry matter and also differs among the cultivars. The composition, granule morphology, and molecular structure of starch are the important characteristics which influence their functional properties and application in the food industry. Microstructural features of sweet potatoes, such as parenchyma cell shape, cell size and composition, and cell wall composition, play important roles in influencing the starch hydrolysis during gastrointestinal digestion. The type of processing method, for example, as boiling, baking, and roasting, has been observed to strongly influence the glycemic properties of sweet potatoes and their products. Several types of modifications including physical, chemical, and enzymatic have been reported for sweet potato starch to tailor its functional properties, which have also been reported to impact its digestive behavior. New healthy and nutritious food products can be developed from sweet potatoes by using suitable cultivars and processing methods.