Modeling the combinatory effects of parboiling and cooking on red paddy rice (Oryza sativa L.) properties

Abstract

Rice is one of the most consumed cereals in the world. Rice parboiling is usually performed to increase its mechanical and nutritional properties. However, parboiling can cause alterations to the texture when it is cooked for consumption, and texture has a major effect on consumer acceptability. Therefore, quantitatively determining and modeling the relationship between parboiling conditions and postcooking characteristics is meaningful from a process control point of view. Thus, the objective of this research was to study and model the influence of steaming time on the properties of red paddy rice before and after cooking. Rice crystallinity decreases with steaming time, suggesting that starch gelatinization under isothermal conditions follows first-order kinetics. Composition, color, and density showed marginal changes as a result of parboiling, while the cooked texture was significantly affected by final cooking time. Although the samples steamed for extended periods of time presented high mechanical properties, they also demonstrated that they reached the final mechanical properties in less cooking time. A second-order kinetic rate equation best described the evolution of the texture properties during cooking and revealed the complexity of the process.