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Background and Objectives: Harvest moisture content (HMC) and milling duration are important factors that influence milled rice quality. The goal of this study is to determine the effect of HMC and milling duration on the physicochemical properties of long grain and medium grain microwave‐dried rice. A long‐grain hybrid rice cultivar (XL753) and a medium‐grain rice cultivar (Titan) with initial HMCs of 16%, 18%, and 20% (wet basis) were sourced from rice farms in Arkansas, USA. The rice samples were dried with the 915 MHz industrial microwave at a specific energy of 525 kJ/[kg‐grain]. The control samples were dried with natural air in an equilibrium moisture content chamber set at 25°C and 56% relative humidity. Following drying, the samples were milled at milling durations of 30, 45, and 60 s, and physicochemical properties were determined. Findings: HMC had significant (p <.05) impacts on head rice yield, crude protein content, and final viscosity of microwave‐dried rice for both cultivars. There were strong positive correlations (Titan: 0.86, XL753: 0.88) between HMC and head rice yield and negative correlations (Titan: −0.85, XL753: −0.62) between HMC and final viscosity of microwave‐dried rice. Milling duration significantly influenced the surface lipid content and whiteness index of microwave‐dried rice for both cultivars. Furthermore, milling duration had significant impacts on the starch damage content and trough viscosity of microwave‐dried rice cultivar XL753 but no significant impact on cultivar Titan. Statistical models predicted HMC of 20% and milling duration of 45 and 42 s for processing microwave‐dried rice cultivars Titan and XL753 respectively, to obtain rice with superior characteristics. Conclusions: HMC and milling duration significantly influenced some physicochemical properties of microwave‐dried rice. We recommend that further studies should be conducted on the cooking, sensory, and storage properties of microwave‐dried rice, to provide information on end‐use and consumer acceptability. Significance and Novelty: This study provides science‐based information that is vital for optimizing the harvesting and processing conditions of rice dried using the 915 MHz industrial microwave. [ABSTRACT FROM AUTHOR]

This study investigated the impacts of selected and broadband infrared (IR) wavelength treatments with tempering step on inactivation of aflatoxigenic molds and the treatments' effects on head rice yield (HRY). Rough rice was treated with different IR intensities, product‐to‐emitter gaps, and heating durations. Afterward, the samples were tempered at 60°C for 4 hr. Selected IR wavelength treatment at intensities of 15.71 and 10.08 kW/m2 for 20 and 30 s resulted in complete aflatoxigenic mold inactivation; broadband IR wavelength treatment with intensity of 10.84 kW/m2 for 30 s resulted in 1.09 log (cfu/g) reduction in aflatoxigenic mold load. Selected IR wavelength treatment (15.71 kW/m2 for 30 s) resulted in 7 percentage points reduction in the mean HRY. Incorporating a tempering step into treatments at IR intensities of 15.71, 10.08, 7.27, and 4.13 kW/m2 resulted in a complete aflatoxigenic mold inactivation. Also, tempering increased the mean HRY of the treated samples. Practical applications: After optimizing the IR parameters tested in this study, the selected IR equipment can be scaled up and commercialized. This novel technique can be used to effectively inactivate aflatoxigenic molds and prevent aflatoxin accumulation on rice, while preserving the milling quality of rice. [ABSTRACT FROM AUTHOR]

In industrial milling of rice, the practice is to target certain degree of milling (DOM) which primarily depend on end-use requirement. Unlike convective heated air (CHA) drying, volumetric heating phenomenon which is associated with industrial microwave (MW) drying of rice at 915 MHz frequency could induce unique changes in rice microstructure; this is likely to impact the rice milling characteristics, especially the DOM. Medium grain rough rice at 24% moisture content (wet basis) at bed thicknesses of 0.01 and 0.05 m was dried in a one-pass, continuous drying operation for 8 min using pilot scale MW set at specific energy of 450, 600 and 750 kJ/kg. Samples from each treatment were milled for durations of 0, 15, 30, 45 and 60 s. The result shows that, more than 80% of the SLC were removed by 30 s of milling duration for both MW and CHA dried samples. Irregular and hexagonal structure typically alluded to starch granules reduced as the specific energy increased. At specific energy of 750 kJ/kg, the core of the MW dried rice kernel indicated features related to thermal decomposition. The study findings are crucial to determining MW drying condition that maintain the rice milling characteristics. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of achieving one-pass drying of high moisture content (MC) rice with microwaves (MWs) set at 915 MHz. Medium-grain rough rice at initial MC of 23% wet basis was dried using a MW dryer set to transmit energy at power levels 5, 10, and 15 kW for 4, 6, and 8 min for rice bed thicknesses of 5, 10 and 15 cm. Increasing MW specific energy up to 900 kJ/kg-grain resulted in increasing rice final surface temperature (FST) and drying rate which together had the effect of lowering the milled rice yield (MRY) and head rice yield (HRY). There was a statistically significant disparity in HRYs across the studied rice bed thicknesses. At the 10 to 15 cm (top) layer, the highest HRYs were observed (64.52%). The 0 to 5 cm (bottom) and the 5 to 10 cm (middle) layers had statistically similar mean HRYs that were both lower than the top layer. [ABSTRACT FROM AUTHOR]

Various processing methods are used in the food industry worldwide to produce numerous rice products with desirable sensory qualities based on cultural and cooking preferences and nutritional considerations. The processes result in variable degrees of macro- and micronutrient content, stability, and retention, depending on rice variety and original nutritional quality. In this article, modern and traditional premilling, milling, and postmilling processing methods of different rice types are comprehensively reviewed. The implications of industrial rice processing methods, especially milling, as well as techniques for nutrient extraction, transfer, and enhancement, such as rice parboiling, sprouting, and fortification, for macro- and micronutrient content and consumer acceptance of the products, are documented. Socioeconomic constraints facing various aspects of rice processing methods are also discussed. This article reviews up-to-date research on rice industrial processing worldwide and aims to benefit engineers dealing with food processing, nutritionists and dieticians, food companies, education and research institutions, and quality-control and safety managers. [ABSTRACT FROM AUTHOR]