Effect of processing conditions on the characteristic and kinetic study of Malaysia parboiled rice MR297

MR297, also known as MARDI SIRAJ 297, is one of the new rice cultivars developed by MARDI. MR297 showed resistance to many diseases but with low milling yield and head rice percentages. Parboiling can enhance milling efficiency, yet limited research exists on parboiled MR297 rice in Malaysia, where domestic production relies on imports. Malaysia should consider the potential for enhancing and promoting domestic parboiled rice production. This study aimed to identify the effects of processing conditions on the physical, chemical, microstructure, and digestibility properties of parboiled rice MR297. Rough rice of the MR297 cultivar was soaked at a 1:1 weight ratio. Paddy was soaked at 50, 60, or 70 °C for 1, 2, 3, 4, and 5 hr, steamed at 100 °C for 20 mins, and dried for 24 hr at 38 °C. Results showed that soaking temperature and duration affected the physical properties of the rice. Kinetic models, including zero-order, first-order, and second-order reactions, were used to assess quality changes in parboiled rice. These findings emphasize the importance of different reaction orders in modelling quality changes, indicating that specific kinetic models can predict and optimize the quality of parboiled rice under various soaking conditions. Meanwhile, a study was done to optimize the effects of the soaking temperature (50–70 °C) and soaking time (2-4 hr) of paddy. Optimal soaking conditions were identified as 54.75 °C and two hours. The optimized parboiling process was then used to investigate the effects of different polishing durations (0, 20, 40, 60, 90, 120, and 150 s) on the physical, colour, hardness, chemical, and milling properties. This study revealed that increasing the polishing duration longer polishing times reducing dimensions, hardness, ash, lipids, and phenolic content while increasing lightness and amylose. The data related to the changes in properties during polishing was then plotted using linear, quadratic, and exponential models. The quadratic model obtained the highest R2 to explain the head rice percentage when the polishing duration increased. This accuracy is critical for optimizing polishing parameters in the rice industry, as it ensures the quality attributes, such as maximizing head rice yield, are maintained. Milled MR297 rice, unparboiled MR297, and local/Malaysian commercially parboiled rice were then cooked in water at 100 °C at selected cooking times (4, 8, 12, 16, 20, and 24 min). Parboiled MR297 showed similar cooking properties to commercial parboiled rice but cooked slower than unparboiled MR297. The data related to the moisture sorption, elongation, and hardness changes during cooking was fitted to nine different models. These models enable the prediction of how parboiled rice will behave during cooking by simulating changes in moisture absorption, grain elongation, and hardness. Its increased slowly digestible and resistant starch content suggests health benefits The optimized parboiling process of MR297 in this study enhance milling efficiency, product quality, and provide economic advantages by offering rice with better cooking qualities, texture, and nutrition.

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