Optimization of heat-moisture treatment on potato starch and study on its physicochemical properties

The object of research is the technology of modified potato starch obtained by heat-moisture treatment. Heat-moisture treatment (HMT) of starch is a hydrothermal treatment technique to modify their functional properties. Setback viscosity of potato starch gelatinization characteristic is the key factor that influences the quality of potato starch noodle. In order to obtain a green, safe and highly efficient potato starch product for vermicelli production, this study take setback viscosity as response value, a Box-Behnken model was established on the basis of single factor experiment results to optimize the modify technique. A response surface analysis was used to investigate the effects of moisture content of starch, heat-moisture treatment temperature and heat-moisture treatment time on setback viscosity of heat-moisture treatment modified potato starch. The viscosity properties, textural properties and retrogradation characteristics of HMT starch gel were estimated. The results of response surface methodology showed the optimal parameters of HMT were that moisture content of potato starch was 23.56 %, heat-moisture treatment temperature was 90 °C, and heat-moisture treatment time was 1.5 h. Under such conditions, setback viscosity of heat-moisture treatment modified potato starch (HMTS) paste was 3677 cP, which was higher than native starch (496 cP) obviously, indicating that the gel strength and hardness of potato starch was improved significantly. Compared with native potato starch (NS), HMTS had lower peak viscosity (2966 cP), lower hold viscosity (2882 cP) and lower breakdown viscosity (84.50 cP), but higher paste temperature (71.08 °C), higher final viscosity (6559 cP) and setback viscosity(3677 cP). The results of retrogradation was consistent with the viscosity properties, all of which indicating that potato starch modified by heat-moisture treatment was more prone to retrogradation. TPA tests demonstrated that HMT can enhance the textural properties of starch gel. Compared with native starch (NS) gel, the hardness, cohesiveness, gumminess, chewiness and resilience of heat-moisture treatment starch (HMTS) gel were increased significantly, and there was no significant difference in springiness. Compared with native starch gel, heat-moisture treatment starch gel had better functional properties.