Modeling of radio frequency heating of egg white powder continuously moving on a conveyor belt

Effect of radio frequency pretreatment on the component of rapeseed and its product: Comparative study with microwave pretreatment under different oil extraction methods

Radio frequency (RF) is an emerging technology for rapeseed pretreatment, offering a comparison to the established microwave (MW) technique. This study investigated the effects of RF and MW pretreatment combined with different oil extraction methods on the oil yield, quality characteristics and lipid concomitant contents of rapeseed and its products. Results indicated that RF combined with pressing extraction yielded the highest tocopherol and canolol contents in rapeseed oil (839.6 and 1316.4 mg/kg, 8.0 % and 7.9 times higher than the control, respectively), and MW combined with supercritical carbon dioxide fluid extraction yielded the highest phytosterol content (8402.0 mg/kg, 16.6 % higher than the control). These results indicate the effectiveness of RF as a novel pretreatment method for rapeseed and its potentially greater advantage than MW. Results also imply that RF could contribute to sustainable and efficient oil extraction processes in the future food industry owing to its high efficiency and energy-saving capability.

Improvement of Temperature Distribution Uniformity of Ready-to-Eat Rice during Microwave Reheating via Optimizing Packaging Structure

The taste quality of ready-to-eat rice is influenced by the uniformity of temperature distribution during microwave reheating. The temperature distribution uniformity of ready-to-eat rice loaded in a rectangular lunch box is investigated under microwave reheating. The results show that with a 10-80 °C temperature increase in the ready-to-eat rice, the thermal conductivity increases, dielectric constant, and specific heat increase and then decrease, while the dielectric loss factor decreases and then slightly increases. The microwave-heating process of ready-to-eat rice exhibits a clear 'corner effect', and the observed 'hot spot' results in poor temperature uniformity in ready-to-eat rice. A metalized packaging structure design is subsequently proposed to ameliorate the temperature non-uniformity. According to comparative results of four metalized packaging forms, the spray film volume and film thickness corresponding to film volume are developed as 3.5×10-4 mL/mm2, 0.30 mm, respectively, which levels off the difference in temperature to improve the temperature distribution uniformity of ready-to-eat rice by microwave reheating.

Microwave heating process of moderate-minced surimi based on multiphase porous media model

Moderately processed surimi products exhibit better nutrient retention and enhanced gels, and the great potential of microwaves application and changes in the way of chopping meat has been reported by previous research. In this study, a systematic analysis of the novel surimi product was made to explore the heat and mass transfer characteristics. A porous media model combining electromagnetic heat and hygroscopic expansion was developed to evaluate this process, and its accuracy has been verified experimentally. It was found that the dielectric characterization of multiphase mixture system has great influence on the results, the complex refractive index mixture equation was used due to its lowest root-mean-square error value. In addition, the effect of moderate processing on microwave heating was examined in terms of porosity changes. However, nonuniform temperature distributions were found in the higher porous samples, especially when the porosity is greater than 0.81. Moreover, the developed model was coupled with the evaluation for gel properties and the results showed the significant effect of moderate crushing on the gel quality during the microwave heating process.