Impact of hydrothermal pretreatments on physicochemical characteristics and drying kinetics of starch from red rice (Oryza sativa L.).

The effects of different hydrothermal pretreatments on the physical chemical characteristics and drying kinetics of red rice starch (Oryza sativa L.) were investigated. The hydrothermal pretreatments chosen include the cooking, autoclave, and steam explosion processes. To obtain the starch in powder form, the pastes were dried at a temperature of 50°C with an air speed of 1.0 m/s. The mathematical models (empirical and diffusive) were adjusted to the experimental data. The starches were submitted to extraction yield, color, water binding capacity, and proanthocyanidins. The values for the diffusivity are between 3.08 × 10−7 and 2.74 × 10−6 m2/min for treatments. The pretreatments of cooking in the grain and autoclave in the starch gave better results than the other studied treatments (formulations), presenting shorter drying time (450 and 510 min) and higher yield (48.60% and 53.54%), respectively. With the application of pretreatments, it is possible to save energy and reduce thermal damage. Novelty impact statement: The results obtained in this study reveals the application autoclave pre‐treatment in red rice starch effectively saves energy and reduces thermal damage as the drying time is shortened. In addition, the drying process information can be used when designing future new equipments. [ABSTRACT FROM AUTHOR]