Effects of temperature and time on gelatinization of corn starch employing gradient isothermal heating program of rapid visco analyzer

Abstract Two process parameters, temperature and time, are mutually interdependent in application of food and feed industries. In order to illustrate the influence of temperature and time on corn starch gelatinization, apparent viscosities of native corn starch samples were measured during different heating treatments by rapid visco analyzer (RVA). The gradient isothermal heating program was developed within 64–95°C. The viscosity gradient and viscosity difference (Δ μ value) before and after isothermal heating were used to determine the critical temperatures. The temperature and time dependence of starch gelatinization were observed, which meant certain temperature and sufficient time were necessary for complete starch gelatinization. Four critical temperatures, at 68, 74, 78, and 88°C, respectively, were obtained from the derivative curve of Δ μ value as the boundaries of different gelatinization stages associating with temperature and time dependence. This study should help starch‐based food and feed industries to better determine the processing parameters for saving energy consumption and cost. Practical Applications Gelatinization, as a functional property during thermal processing of starch, is applied extensively in starch‐based food industry and feed industry. Heat‐moisture treatment is one of the most conventional processing procedures for starchy raw materials. Furthermore, temperature and time, two controllable parameters influencing quality of products, should be carefully concerned. Since the temperature and time dependence of gelatinization during processing has not been specified sufficiently, the present study developed a gradient isothermal heating program through custom configuration files of rapid visco analyzer (RVA) for illustrating the effects of temperature and time on gelatinization of corn starch unlike previous RVA analysis. Critical temperatures and the sensitivity of holding time were obtained from viscosity characteristics. The results would be useful to control products quality in food and feed industry.