Abstract:In the study of gelatinization characteristics and kinetics of starchy raw materials, hydrothermal treatment with controllable parameters was needed, but the effect of heating methods on homogenization of temperature distribution of samples was usually neglected. A device and method for clamping and heating feed samples with cast aluminium plates were presented. The moistureadjusted feed samples were sealed in zip lock bags and clamped in a set of parallel temperaturecontrolled cast aluminium plates for heating treatment. Based on onedimensional heat conduction equation, the temperature curves from room temperature to setting temperature were obtained by using the finite difference method of Matlab, and the temperature homogenization of feed samples during heating process was evaluated. The results showed that the device could achieve full homogenization of samples temperature distribution in a short time, and the time scale for achieving homogeneous temperature distribution of samples was much smaller than the gelatinization time scale, which indicated that the time for heat treatment of samples could be controlled accurately. On this basis, taking the formula feed for finishing pigs as research material, the pasting temperature, pasting time and feed moisture were selected as the influencing factors, and the degree of gelatinization was selected as evaluating indicators, thus the quadratic regression orthogonal rotatory combination experiments were carried out. As a consequence, the order of influence of each factor on feed gelatinization degree was feed moisture, pasting temperature and pasting time. A quadratic regression model (R2=0.9420) for feed gelatinization degree and three factors was established by regression analysis and response surface analysis with DesignExpert software, and the validity of the regression model was verified. In the analysis of chromatic aberration of feed samples after heat treatment, it was found that excessive heat treatment temperature would not increase the gelatinization degree of feed under certain conditions; on the contrary, it would intensify Maillard reaction leading to the deepening of feed color and affecting the appearance quality.
