Behavior of Sweet Potato Starch After Spray-Drying Under Different Pretreatment Conditions

Abstract

There are a lot of potential uses of sweet potato as a source of starch in food and other industries. Pregelatinization, a physical modification that confers properties of interest for several industrial applications, is a way to expand the use of this starch. Processing conditions have significant impact on the properties of modified starch and therefore, the effects of the concentration of starch and preheating temperature on the physical properties of spray dried starch in this study are evaluated. This study is carried out by applying a central rotational compound experimental design to test two independent variables, starch concentration and preheating temperature, and consisted of a total of 11 treatments. Results showed that the granule size, gelatinization temperature, and breakdown viscosity are significantly affected by the preheating temperature. Besides this, preheating temperature and starch concentration also influenced the crystallinity percentage, enthalpy change, gelatinization degree, retrogradation properties, and final viscosity. The final products showed lower crystallinity percentage, enthalpy change, and onset and peak dissociation temperature, as well as, higher peak gelatinization temperature, retrogradation rates, swelling power, and solubility, independent of processing conditions, when compared with native sweet potato starch. Partially pregelatinized starch with high viscosity and resistance to heating under agitation can be obtained under the process conditions consisting of up to 8% starch concentration and a preheating temperature of 60 °C. These acquired properties can potentially boost the use of sweet potato starch in food industries.