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The aim of this study was to optimize sequential ultrasound-radio frequency–assisted extraction (URAE) of pectin from pomelo peel. Effects of sonication power and time, radio frequency (RF) heating temperature, and time on the pectin yield (PY) were evaluated. Based upon optimized URAE parameters, the yield, physicochemical, and structure properties of pectin recovered from sequential radio frequency-ultrasound–assisted extraction (RUAE), ultrasound-assisted extraction (UAE), and RF-assisted extraction (RFAE) were also compared. A maximal PY of 28.36 ± 0.85% was attained at the optimized URAE conditions including solvent pH of 1.5 (citric acid), sonication at 183 W for 24 min, and RF heating at 87 °C for 23 min. Although all four samples had a high degree of esterification more than 50%, URAE was the lowest. No significant changes were observed in the types of monosaccharides among different samples. Furthermore, all four samples (6.6–10.3 mg GAE/g) showed significantly higher total phenolic content than those of commercial citrus pectin (1.2 mg GAE/g), and among them, RFAE was the highest with the best antioxidant capacity. The water and oil holding capacities of the four samples were between 3.5 to 4.0 and 2.6 to 3.0 g/g, respectively, but there was no significant difference (p > 0.05) between each other. Structure properties indicated that there were no significant differences in the main chemical structures among the four pectin samples. Morphology analysis of URAE showed a more compact, smoother, and flatter surface than that of RUAE and RFAE. The results observed in this paper suggest that sequential URAE is an efficient strategy for the recovery of high-quality pectins. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Application of radio frequency (RF) treatment has been studied for disinfesting agricultural products, and RF heating non-uniformity has been demonstrated to directly influence pest mortality in treated products. The purpose of this study was to investigate the combined effects of holding time after conveyor movement, layer rearrangement, and sample mixing on the mortality of Rhyzopertha dominica (R. dominica) in milled rice treated with hot air-assisted RF heating. Results showed that hot-air assistance during the process of RF heating can lead to a rapid temperature rise and improve the temperature distribution. RF heating followed by holding samples in hot air for specific time periods effectively improved the heating uniformity of samples and raised the mortality of R. dominica in milled rice. Compared with the stationary conditions, conveyor movement, layer rearrangement, and sample mixing improved the hot air-assisted RF heating uniformity of the sample, raised pest mortality and reduced the thermal holding time after RF treatment required to achieve 100% pest mortality in milled rice. The findings of this study provide a valuable proof of concept for improving RF heating uniformity and optimizing parameters in RF disinfestation protocols for milled rice. [ABSTRACT FROM AUTHOR]

This review presents an analysis of the existing concepts for the utilization of electric power for heating chemical reactors, primarily those designed for heterogeneous catalytic processes. The paper provides a brief outline of major electric heating methods in the context of chemical applications, mentions important examples of the industrial implementation of electric heating, and evaluates the prospects for industrial use of electric heating instead of conventional heating systems. [ABSTRACT FROM AUTHOR]

This study investigated the optimal design of a radio-frequency (RF) bone tumor ablation device to achieve uniform heating. In a previous study, we confirmed the feasibility of this device, which could heat all regions of the bone to 70 °C or higher and maintain this temperature for more than 30 min. However, the temperature in each part was non-uniform. To address this issue, the shape of the electrode must be modified to create a uniform electric field. The design of the electrode was optimized to reduce temperature deviations. It is difficult to analytically model the relationship between the shape of the electrode and the electric field. The electrode's design factors were fine-tuned using the Taguchi method, a robust design of experiment approach. The primary objective in this optimization was to maximize the signal-to-noise ratio for temperature in each component, aiming for higher values. After four trials, the signal-to-noise ratio increased in comparison with the initial modified shape from 68.3 to 98.6. The experiment was conducted using an experimental device fabricated using the optimal design factors. In comparison to the previous experiment, the temperature standard deviation per part over time decreased from 10.56 °C 4.28 °C. The experimental results demonstrated the validity of the proposed optimal design approach. In the future, the proposed method can be used to optimize the design factors when a product is advanced to develop a device that can be applied to the human body. [ABSTRACT FROM AUTHOR]

This paper presents a new Monte Carlo algorithm intended for use in orbit following Monte Carlo codes (OFMC) to describe resonant interaction of ions with Radio Frequency (RF) waves in axi-symmetric toroidal plasmas. The algorithm is based on a quasi-linear description of the wave–particle interaction and its effect on the distribution function of a resonating ion species. The algorithm outlined in the present paper utilises a two-step approach for the evaluation of the Monte Carlo operator that has better efficiency and a stronger convergence than the standard Euler–Maruyama scheme. The algorithm preserves the reciprocity of the diffusion process. Furthermore, it simplifies how the displacement of the resonance position, as a result of wave–particle interaction, is accounted for. Such displacements can have a noticeable effect on the deterministic part of the Monte Carlo operator. The fundamental nature of guiding centre displacements of resonant ions as a result of wave–particle interaction is reviewed.

Copyright of Taiwanese Journal of Agricultural Chemistry & Food Science is the property of Agricultural Chemical Society of Taiwan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agricultural products usually contain a large number of spoilage bacteria and endogenous enzymes, which can adversely affect the quality of agricultural products. Radio frequency is a kind of dielectric heating technology, which has fast heating speed and high efficiency, can effectively inactivate microorganisms and endogenous enzymes in agricultural products and has little influence on the quality of agricultural products， such as color, texture and nutritional composition, etc. This review summarized the mechanism of action of radiofrequency sterilization blunt enzyme technology and its application in agricultural products processing in recent years, and the shortcomings and solutions of radiofrequency sterilization blunt enzyme technology was pointed out. Moreover, the future application of radiofrequency sterilization blunt enzyme technology in agricultural products and food was also prospected.

The present study proposes an approach to overcome the problem of corner/edge overheating of foods undergoing radio frequency heating. For testing, a container with a central rectangular compartment surrounded by a frame of four compartments was used. Wheat flour, a representative of low-moisture foods, was packed inside the rectangular compartment to provide a density of 800 kg/m3. Afterwards, in the surrounding compartments, air, deionized water and NaCl solution were used for independent radio frequency heating tests. Two different electrode gaps (135 and 145 mm) were employed. The temperature of the sample was measured continuously using fibre optic probes at four different internal locations. The difference between the maximum and the minimum temperatures for three different cases (a: air, b: deionized water and c: NaCl solution) were as follows for electrode gaps of 135 and 145 mm, respectively: (a) 27.3 and 26.1 °C, (b) 2.5 and 4.8 °C and (c) 3.7 and 1.8 °C. Uniformity index values were also calculated. The results showed that temperature variation within the sample was greatly reduced when the sample was surrounded by deionized water or NaCl solution. PRACTICAL APPLICATION The project findings will provide processors with a practical means to achieve more uniform radio frequency heating of low-moisture foods. [ABSTRACT FROM AUTHOR]

Several numerical simulations of RF heating have been carried out previously on the estimation of heavy oil recovery capabilities. Experimental efforts, however, are needed to comprehensively evaluate the performance of RF heating technology. In this study, an RF heating experimental system with the maximum output power of 20 kW is designed. In this system four special custom-made experimental pipes provide the space where the interaction between EM waves and oil sands occurs. Temperature data are recorded continuously by fiber optic temperature sensors. Initially, the temperature profiles of oil sands and quartz sands at 10 kW are obtained. Afterward, the step changes in temperature of pipes bottoms are captured to investigate the drop process of heavy oil. The influences of different powers and distances from the antenna on temperature and recovery ratio are analyzed. Finally, according the measured data, the calculation for the energy to oil ratios under various combinations of time and power is done to evaluate the energy consumption of RF heating technology. Experimental results indicate that the power increase contributes to improve the oil sands temperature, shorten the time required for heavy oil to flow and cause high average recovery ratio. The capability of oil sand to absorb EM waves is stronger than that of quartz sands. Additionally, the effects of distance from antenna on average recovery ratio are in good agreement with the change rules of temperature. There exists an optimal combination of heating power and time that makes the lowest value of energy to oil ratio. [ABSTRACT FROM AUTHOR]

Copyright of Food & Machinery is the property of Food & Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Radio frequency (RF) heating of agri-food, especially low moisture viscous sauces (LMVS), have obvious advantages. However, uneven heating is one main problem of RF heating technology that has to be solved. Due to the unclear heating mechanism and the difficulty to measure the three-dimensional temperature distribution in the heated object, computer-aided analysis method was adopted. Based on the RF heating numerical calculation model after experimental verification and the characteristics of polyetherimide (PEI) assisted RF heating of peanut butter (PB), this study proposed an improved method for an existing protocol. Meanwhile, parameters of the new protocol were optimised by the Multi-objective Global Optimisation (MGO) of its surrogate model. Results demonstrated that the best size of PEI block in the new protocol was Φ100 × 9.5 mm and the positional height was 12 mm. When the pasteurisation temperature Tp was set to 70 °C and the control temperature Tc was set to 75 °C, the temperature uniformity evaluation indices, Over-shoot Temperature Control Index (OTCI) and Targeted Penetration Depth (TPD), were 0.920% and 3.975 mm, respectively. Compared with 4.845% and 4.940 mm before improvement, the new protocol achieved significant optimisation and improved the temperature uniformity effectively. This also proved the feasibility of MGO method of surrogate model in relevant studies. [ABSTRACT FROM AUTHOR]

Drying is one of the most important technologies for fruit and vegetable processing. The energy consumption during drying and the quality of dried products are highly correlated to the selected drying methods. As a new type of physical heating technology, radio frequency (RF) heating technology has attracted much attention in recent years because of its rapid heating, volume heating effect, long energy penetration depth, even microorganism control, and enzyme deactivation. This paper mainly summarized the mechanism and characteristics of RF heating technology, the factors that affecting RF heating technology application in fruit and vegetable. Moreover, the application status of RF technology in fruit and vegetable drying, microorganism control, and enzyme deactivation are also concluded. Finally, the existing problems, possible solutions and future development trends of RF heating technology in fruit and vegetable drying are also proposed. This review could provide theoretical guidelines for RF industrial application in fruit and vegetable drying in the future.

A two-stage biodiesel production directly from wet microalgae (Chlorella vulgaris) assisted by radio frequency (RF) heating was optimized in this study with the response surface methodology (RSM) applied to both two steps. In order to apply RSM to the two stages rather than to a one-step reaction, a three-variable, five-level central composite design (CCD) was employed to evaluate the effects of three key parameters, i.e. HCl to MeOH ratio (v/v), MeOH volume, and RF heating time. Two regression equations (one regression equation for each stage) were obtained, and two sets of optimized production conditions with a slight difference were also determined. The best predicted FAME yield of 93.1% was obtained at a HCl to MeOH ratio of 4.27 (v/v), a MeOH volume of 28.5 mL, and a RF heating time of 19.2 min. Although the second stage of conversion increased the FAME yield from 82.9% to 93.1%, this process would cause additional consumption of time, solvent, and energy. Verification experiments were carried out at the optimized point and resulted in a yield of 92.7 ± 0.1%, which validated the reliability of the prediction model. All processing steps, including cell destruction, esterification, and transesterification, were carried out at temperatures below 100°C and atmospheric pressure. Therefore, no pressure-proof nor high-temperature apparatus was required. The procedure shows great potential for industrial application because of its high FAME yield, simple operation, low chemical consumption, and short processing time. The principles of the procedure can also be applied to other microalgae with high lipid contents. [ABSTRACT FROM AUTHOR]

Several recent studies have found that measuring the dielectric permittivity of soil can be used to determine the level of environmental pollution. However, there is limited research on the measurement of dielectric properties in soil contaminated with biodiesel-diesel blends from Thailand. This paper presents to monitor the dielectric properties of soil contaminated with biodiesel-diesel blends. Specifically, we use the commercial grade diesel B7 to contaminate a sample of sand soil. We also study the measurement of dielectric properties in contaminated soil with the diesel B7 using a dual electrode plate-based radio frequency (RF) heating system. This allows us to observe the behavior of the contaminated soil before and after RF heating treatment. The experimental result showed that the dielectric properties of uncontaminated and contaminated soil were different. In addition, the RF heating system utilizing the electric field intensities of 450 kV/m resulted in the dielectric properties of the contaminated soil becoming similar to those of uncontaminated soil. These findings suggest that using RF heating on contaminated soil samples improve the air in the pore space compared to unheated contaminated soil. This approach may be effective for the treatment of soil in Thailand using an RF heating system with dual electrode plates. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel combined RF and alkaline treatment shows significant synergistic effects. • Combining RF and alkali result in a 9-fold increase in VFAs production. • A 35.11% disintegration rate of sludge by combined pretreatment was reached. • An optimal ionic concentration for RF treatment was approximately 1000 μs/cm. Sludge pretreatment plays a crucial role in solubilizing particulate matters to release organic matter for subsequent anaerobic fermentation (AF). This study innovatively combines radio frequency (RF) heating and alkaline treatment, and finds that the combined pretreatment achieved a sludge disintegration rate of 35.11 %, which is 15.19 % and 8.48 % higher than single RF or alkaline pretreatment. The dissociated ions from the alkali are conducive to RF action on sludge. Furthermore, the combined pretreatment significantly benefits the subsequent AF experiments, resulting in a 9-fold increase in volatile fatty acids production. Considering cost-effectiveness, the optimal operating condition is a 10-minute RF treatment at pH 10 with a total cost of 4.35 × 10-3 dollars per kg soluble chemical oxygen demand (SCOD) increased. These findings provide a foundational basis for the development of a novel technology for sludge pretreatment. [ABSTRACT FROM AUTHOR]

Direct Ink Writing (DIW) is an extrusion-based additive manufacturing method where the print medium is a liquid-phase 'ink' dispensed out of nozzles and deposited along digitally defined paths. Conventional DIW of thermosetting resins relies on viscosity modifying agents, novel crosslinking chemistries, and/or long curing schedules in an oven. Here we demonstrate the use of a co-planar radio frequency applicator to generate an electric field, which can be used to rapidly heat and cure nano-filled composite resins as they are printed. This method avoids the need for an oven or post-curing step. This process consists of a sequential print-and-cure cycle which allows for printing of high-resolution, multi-layered structures. Every extruded layer is partially cured using RF before depositing the next layer; this allows the printed part to maintain structural integrity. The process enables both increased throughput and decreased touch time relative to traditional manufacturing. Commercial epoxy resin with varied nano-filler loadings were examined as DIW candidates. After printing, the thermo-mechanical properties, surface finish, and shape retention of RF-cured samples were comparable to conventionally cured samples. This method of manufacturing establishes RF heating as a suitable alternative to conventional methods, facilitating rapid, free-form processing of thermosetting resins without a mold. [Display omitted] [ABSTRACT FROM AUTHOR]

The storage and processing of grain are the basis for economic and social stability and development. As a new heating treatment technology based on electromagnetic wave, radio frequency technology has the characteristics of large penetration depth, rapid heating, volumetric heating and no chemical residue. It has been widely used in post-harvest research of grain and has potential industrial application prospects in some fields. To expound the research progress of the application of radio frequency heating technology in grain storage and processing, this review briefly described the basic principle and characteristics of radio frequency heating as well as the current commercial radio frequency heating system including free oscillation type and 50 Ω type. The basic research of radio frequency heating in grain storage and processing was summarized from three aspects: Dielectric properties of grain and pests, heat resistance of stored grain pests and heating uniformity of sample. The dielectric properties refer to the interaction between materials and electromagnetic waves in an electromagnetic field and determines the absorption and conversion of electromagnetic energy. It can predict the heating characteristics of grain and provide basic data for computer simulation to optimize process during radio frequency treatment. The heat resistance data of pests are necessary for the establishment and optimization of dis-infestations technology, so the kinetic date of thermal death of common stored grain pests were reported in this review. As a main hinder in the commercial application of radio frequency treatments, the heating uniformity has significant effect on heat treatment quality and results in potential food safety problems. The major factors causing heating non-uniformity are the non-uniformity of electromagnetic field, runaway heating and the sample shape effect. The improvement methods of heating uniformity were summarized from three aspects in this article including changing the electromagnetic field distribution, sample position, and optimizing the radio frequency working parameters. Based on the above basic research of radio frequency technology and combining with the practical problems in grain storage and processing, the applications of radio frequency heating in the fields of dis-infestations, sterilizing, enzyme inactivation and drying were also summarized. Finally, some suggestions on the application of this technology in grain storage and processing and future research directions were proposed. This review may play a certain guiding role for the application of radio frequency technology in grain storage and processing.

At present, steam-assisted gravity drainage technology has failed to meet the requirement for the large-scale development of abundant oil sands resources due to high production cost and serious environmental pollution caused by huge amounts of carbon emissions. Therefore, this paper proposes a radio frequency technology for heating oil sands and establishes a corresponding mathematical model that considers the phase transition of water. Then, a lab-scale experimental setup is designed to experimentally investigate the performance of radio frequency heating based on the phase change. Finally, the influences of phase transition of water on the temperature distribution of oil sand samples are analyzed in detail. The results show that the mathematical model of radio frequency heating can accurately predict the temperature distribution prior to the phase transition of water due to the little effect of phase transition on the thermal properties and density of oil sand samples. The failure to consider the effect of phase transition of water on electrical conductivity of oil sand in the mathematical model accounts for a large deviation between the measured temperature data and numerical results. So, in order to make the calculated temperature results more accurate, this effect should be considered during numerical simulation. [ABSTRACT FROM AUTHOR]

With the changing lifestyles and the rapid development of the prepared food industry, there are many different multi-component rice-based foods on the market today. Further, manufacturers of multi-component foods prepare different types of rice products and provide them to markets and restaurants. In this study, the multi-component rice was heated by a self-built small 50 Ω, 13.56 MHz radio frequency (RF) heating system to explore the effective scheme for improving heating uniformity. The dielectric properties (DPs) of the single-component material (cooked rice, carrot, and sausage) were first measured and the heating rates were recorded at a selected input power level of 500 W and electrode gap of 80 mm. Based on the above results and the occurrence of edge effect, three types (I, II, and III) of the multi-component test samples were designed to compare the heating performances and the quality changes after RF treatment with three different electrode gaps (70, 80, and 90 mm). Results demonstrated that the Type-I sample arrangement resulted in a relatively shorter treatment time and a lower heating uniformity index as compared to the other two sample arrangements (Types of II and III). It also resulted in a more uniform temperature distribution and better-quality retention than that was possible with the single-component treatment. Thus, the layered scheme (Type-I) based on the DPs of the material could effectively improve the RF heating uniformity of multi-component food. • Extended application of small-scale RF systems was conducted in multi-component rice. • Three sample distribution arrangements were designed to improve the RF heating uniformity. • Type-I sample arrangement resulted in a shorter treatment time and better heating uniformity. • RF heating uniformity in multi-component rice was improved based on layered component dielectrics. [ABSTRACT FROM AUTHOR]

Enzymatic browning is one of the main problems in the food industry, especially in juice and jam processing. An efficient approach to reduce enzymatic browning is to inactivate key polyphenol oxidases (PPO) that cause color reactions. Radio frequency (RF) treatment has advantages of volumetric heating and no chemical residue, making it one of the most potential treatments to replace traditional heating for pasteurization. In this study, a finite element model was established using the commercial software, COMSOL, to investigate the feasibility and effectiveness of PPO inactivation in non-Newtonian characteristic liquid food with high viscosity during pilot-scale RF treatments. The PPO was represented by the tyrosinase, and four concentrations of carboxymethylcellulose (CMC) solutions were considered to have high viscosity and non-Newtonian characteristics for liquid food. The results showed that the relative residual enzyme activity rapidly decreased to 1.2% when the target temperature increased to 70 °C during a batch RF enzyme inactivation. Meanwhile, the simulated and experimental trends were consistent with an acceptable RMSE value. The low-concentration CMC solutions (0.5% and 1.0%) with shorter heating times may be more suitable for developing the batch RF enzyme inactivation technology. During continuous-flow RF enzyme inactivation, the F -value increased with an increase in the solution concentration but sharply decreased with an increase in the volumetric flow rate. The exponential function could be used to describe the relationship between the relative residual enzyme activity and the volumetric flow rate of the CMC solution after RF treatment. The optimal volumetric flow rates for reducing the activity of PPO in 0.5%, 1.0%, 1.5%, and 2.0% CMC solutions to 20% were 426.13, 467.87, 552.05, and 566.07 mL/min, respectively. This study can provide valuable information for inactivating enzymes in non-Newtonian characteristic liquid food with high viscosity. • The relative residual enzyme activity decreased to 1.2% when the temperature increased to 70 °C. • The F -value increased with an increase in the solution concentration. • The F -value decreased with an increase in the volumetric flow rate of the CMC solution. • The optimal flow rates for reducing the activity of PPO increased with an increase in the solution concentration. [ABSTRACT FROM AUTHOR]

Summary: Radiofrequency (RF) heating is an alternative emerging technology to conventional thermal methods; it has been employed for food pasteurisation, providing fast and volumetric heating. However, non‐uniformity in the heating pattern has been reported. RF pasteurisation has been studied in different liquid foods. This review provides information about the RF heating mechanism and equipment used to pasteurise liquid food to control deteriorative or pathogen micro‐organisms and the effect of the RF treatment on the quality of liquid foods. Developing an effective RF pasteurisation for liquid foods requires knowing the food dielectric properties, which determine the heating uniformity, temperature distribution and heating rate. The efficiency of continuous RF heating systems could depend on the fluid rate, resident time and absorbed power. RF heating can pasteurise liquid food, decrease microbial population and preserve the product's nutritional and physicochemical quality. [ABSTRACT FROM AUTHOR]

Summary: The present study aimed to investigate the influence of radio frequency (RF) heating at 70 and 80 °C, in comparison with the traditional conventional heating. The RF heating technology was applied for maintaining the colour and textural quality as well as inactivating the enzymatic activity of polyphenol oxidase (PPO) and reducing the Escherichia coli growth in packaged fresh‐cut peach samples. To evaluate this, 120 g of freshly cut peach fruit was placed in heat‐resistant plastic bags, and 50 mL of sugar solution (12°Brix) was added to each bag and vacuum‐packed for conventional heating and radio frequency (RF) heating. Our results demonstrated that the RF heating process could reduce the heating time by up to 83% at 70 and 80 °C as compared to conventional heating. Moreover, RF heating at 70 and 80 °C reduced the PPO enzymatic activity, which caused enzymatic browning, up to 85.46% and 93.5%, respectively, as compared to 40.86% reduction only for conventional heating. Furthermore, RF heating completely inhibited E. coli growth. Collectively, we demonstrated that RF heating is an emerging and promising technology for improving the quality of fresh‐cut fruits such as peach during various storage conditions. The present study provides relatively novel information on the effectiveness of RF heating in maintaining the quality of fresh‐cut peaches. In the future, we would like to investigate the effectiveness of RF heating on other agricultural products. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the effect of the milling degree (MD) of rice (Oryza sativa L.) on the heating rate, pathogen inactivation (Salmonella Typhimurium and Staphylococcus aureus), and color change resulting from radio frequency (RF) heating. Rice samples inoculated with pathogens were placed in a polypropylene jar and subjected to RF heating for 0 to 75 s. The heating rate of rice with a 2% MD was the highest during RF heating, followed by those with a 0, 8, and 10% MD; the reduction of pathogens showed the same trend. The reductions of pathogen levels in rice with MDs of 0 and 2% were significantly higher than those observed for rice with MDs of 8 and 10% under the same treatment conditions. For example, log reductions of Salmonella Typhimurium in rice by 55-s RF heating were 3.64, 5.19, 2.18, and 1.80 for MDs of 0, 2, 8, and 10%, respectively. At the same treatment conditions, log reductions of S. aureus were 2.77, 5.08, 1.15, and 0.90 for MDs of 0, 2, 8, and 10%, respectively. The color of rice measured according to L*, a*, and b* was not significantly altered after RF heating, regardless of the MD. Therefore, the MD of rice should be considered before RF heating is applied to inactivate foodborne pathogens. MD of rice significantly affects RF heating rate (ca. 30°C difference after 55-s treatment). Salmonella and Staphylococcus inoculated in rice were inactivated by RF (>5 log CFU/g). MD affected the rate of pathogen reduction (>3 log CFU/g difference after 55-s treatment). Color values were not significantly changed after RF treatment. [ABSTRACT FROM AUTHOR]

Spectral intensities emitted from high- $Z$ metal impurity ions of Fe22+ at 132.91 Å, Mo30+ at 115.999 Å, Mo31+ at 127.868 Å, W42+ at 129.41 Å, W43+ at 126.29 Å, and W45+ at 126.998 Å and their radial profiles have been observed in EAST plasmas using a space-resolved extreme ultraviolet (EUV) spectrometer. Local emissivity profiles of the emission lines are obtained from the line-integrated profile through the Abel inversion based on the magnetic equilibrium calculation from the equilibrium fitting (EFIT) code. Then, the density profile is analyzed for Fe22+, Mo31+, W43+, and W45+ ions in the $L$ - and $H$ -mode plasmas with lower hybrid wave (LHW) or electron-cyclotron-resonance (ECRH) heating using measured electron temperature and density profiles and photoemission coefficients (PECs) from the ADAS database. It is found that the density profile of Fe22+, W43+, and W45+ ions has a peak value of $0.48\times 10^{8}$ , $2.34\times 10^{8}$ , and 1.55 $\times 10^{8}$ cm−3 at $\rho$ = 0.13–0.17 in the LHW and ECRH-heated $L$ -mode plasmas, respectively. In the $H$ -mode plasma with higher ECRH power, on the other hand, the peak position in the density profile outwardly shifts toward radial positions of $\rho$ = 0.20–0.26. The density profiles also show an increase in the peak value in comparison with the $L$ -mode plasma case, i.e., increases to 0.7, 2.8, and $1.7\times 10^{8}$ cm−3 for Fe22+, W43+, and W45+ ions, respectively. When the ICRF heating is applied to the $H$ -mode plasma, the peak density significantly increases, i.e., 0.9, 3.6, and $2.3\times 10^{8}$ cm−3 for Fe22+, W43+, and W45+ ions, respectively. [ABSTRACT FROM AUTHOR]

Conventional hot air and solar energy processes have been used for apricot. These processes had adverse effects on the quality due to the longer process times, and this indicates the need for an innovative approach. Radio frequency (RF) processing has innovation potential for drying with its volumetric heating feature, but an optimal process should be designed for process efficiency in industrial‐scale applications. Therefore, the objective of this study was to confirm the RF process for industrial‐scale apricot drying. For this purpose, a mathematical model was developed to predict temperature and moisture content change of apricots during drying, and experimental validation study was carried out. For the RF drying process, pre‐dried apricots (0.58–0.75 kg water/kg dry matter, db) by solar energy were used. The purpose was to start the RF process at a suitable moisture content level as this process was not feasible to apply directly due to the high initial moisture content of apricots (up to 4 kg water/kg dry matter, db). RF drying experiments were carried out in a 10 kW hot air‐assisted (50–60°C) staggered through electrode system. Optimum electrode gap was 81 mm with 2500 V potential of the charged electrode. Final moisture content of the dried apricots was 0.25–0.33 kg water/kg dry matter (db). Following the model validation for temperature and moisture content change, industrial‐scale apricot drying scenarios were demonstrated to confirm the RF process for feasibility and process design. Practical Application: A comprehensive mathematical model was developed for radio frequency (RF) drying of apricots. This model was experimentally validated with respect to the temperature and moisture content change. Various process design studies were carried out for an industrial‐scale apricot drying process to confirm the process feasibility. With this background, the results of this study can be directly used in an industrial drying for an optimal process design and energy efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: Artifacts limit the application of proton resonance frequency (PRF) thermometry for on-site, individualized heating evaluations of implantable medical devices such as deep brain stimulation (DBS) for use in magnetic resonance imaging (MRI). Its properties are unclear and the research on how to choose an unaffected measurement region is insufficient. Methods: The properties of PRF signals around the metallic DBS electrode were investigated through simulations and phantom experiments considering electromagnetic interferences from material susceptibility and the radio frequency (RF) interactions. A threshold method on phase difference Δϕ was used to define a measurement area to estimate heating at the electrode surface. Its performance was compared to that of the Bayesian magnitude method and probe measurements. Results: The B0 magnetic field inhomogeneity due to the electrode susceptibility was the main influencing factor on PRF compared to the RF artifact. Δϕ around the electrode followed normal distribution but was distorted. Underestimation occurred at places with high temperature rises. The noise was increased and could be well estimated from magnitude images using a modified NEMA method. The Δϕ-threshold method based on this knowledge outperformed the Bayesian magnitude method by more than 42% in estimation error of the electrode heating. Conclusion: The findings favor the use of PRF with the proposed approach as a reliable method for electrode heating estimation. Significance: This study clarified the influence of device artifacts and could improve the performance of PRF thermometry for individualized heating assessments of patients with implants under MRI. [ABSTRACT FROM AUTHOR]

Copyright of Smart Agriculture is the property of Smart Agriculture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Several recent studies have found that measuring the dielectric permittivity of soil can be used to determine the level of environmental pollution. However, there is limited research on the measurement of dielectric properties in soil contaminated with biodiesel-diesel blends from Thailand. This paper presents to monitor the dielectric properties of soil contaminated with biodiesel-diesel blends. Specifically, we use the commercial grade diesel B7 to contaminate a sample of sand soil. We also study the measurement of dielectric properties in contaminated soil with the diesel B7 using a dual electrode plate-based radio frequency (RF) heating system. This allows us to observe the behavior of the contaminated soil before and after RF heating treatment. The experimental result showed that the dielectric properties of uncontaminated and contaminated soil were different. In addition, the RF heating system utilizing the electric field intensities of 450 kV/m resulted in the dielectric properties of the contaminated soil becoming similar to those of uncontaminated soil. These findings suggest that using RF heating on contaminated soil samples improve the air in the pore space compared to unheated contaminated soil. This approach may be effective for the treatment of soil in Thailand using an RF heating system with dual electrode plates.

Radio frequency (RF) sterilization of low-moisture, high-oil, high-protein, and viscous sauces for instant food (LHHVS) demonstrates many advantages, but uneven heating is a main problem that must be addressed. Main factors that affect heating uniformity are generally considered dielectric properties, shape and size of the sample and its position relative to the electrode plate, in addition the structure and voltage of RF electrode. A method based on texture characteristics of the solid–gel–liquid mixing system of LHHVS for adjustment and control of energy distribution in the RF field is proposed in this study to improve the heating uniformity. First, energy conversion principles and control equations of RF heating were analyzed on the basis of dielectric theory. Second, the influence of RF electromagnetic field-medium polyetherimide (PEI) on the RF heating of peanut butter (RHPB) was investigated on the basis of the numerical model of RHPB that was verified through experiments. Finally, the influence mechanism and its regulation and control effect were analyzed and discussed. The following conclusions can be drawn from this study: the increase of electrode gaps exerts minimal effect although it reduces the unevenness of the energy distribution. However, RF heating protocols must use the smallest possible electrode gap to heat agrifoods and increase the heating rate significantly. The energy distribution on the part of the sample close to PEI varies with the change of geometry and size of PEI when its placement is bias or symmetric. The area of energy enhancement continues to expand where the sample is in contact with PEI as PEI gradually increases. The area where the temperature increases under the influence of PEI will expand along the direction of the sample radius when the thickness of PEI remains unchanged and the radius gradually enlarges; otherwise, it will expand along the direction of the sample thickness. The influence of PEI on the energy distribution of RHPB demonstrates local characteristics. PEI significantly influences the energy distribution and heating mode of RHPB, which is easy to adjust and control, but does not reduce the processing speed and does not increases energy consumption. Hence, PEI is an effective means to interfere with energy distribution of RHPB. Uniform energy distribution can be obtained by selecting the appropriate PEI shape and size. Results of this study can help determine the experimental protocol for RHPB with the optimal uniform distribution and promote the fast commercial application of this technology. [ABSTRACT FROM AUTHOR]

This study aimed to assess the impact of various processing parameters including electrode gap, packaging geometry, and particle size on the heating efficiency of radio frequency (RF) processing for peanut thermal decontamination. In addition, interlayer displacements were presented to evaluate the effect of the mixing on heating uniformity. Experimental studies were carried out using 3D-printed polylactic acid (PLA) containers (square, rectangular, and cylindrical) to place the peanut samples with particle sizes ranging from 0.71 to 2.00 mm at 100–140 mm electrode gaps. Temperature changes within the samples were monitored using fiber optic sensors and surface temperature distributions were determined with an infrared camera. Heating uniformity index (λ) was then calculated to assess the effects of RF processing conditions on RF heating uniformity. Results showed that the cylindrical container exhibited a more consistent and uniform heating profile (λ = 0.12) with 1.58 °C min−1 heating rate compared to other containers, and a single interlayer displacement between top and bottom layers further improved temperature distribution uniformity. Smaller particle sizes also led to faster heating rates from 1.71 to 1.55 °C min−1 with more uniform heating due to the reduced porosity within the particles with increased thermal conduction and electromagnetic energy absorption. This study presented valuable insights for developing an effective RF process as an alternative to conventional thermal treatments for decontamination of low-moisture, high-fat particulate foods. This research presented an innovative approach applying RF heating for a possible decontamination process for peanut samples. The research tackled the growing worldwide consumer demand for food products to satisfy food safety regulations while peanuts were selected to demonstrate the process effect due to the recent food safety issues in peanut butter considering that a pre-process for decontamination would lead to a decrease in the resulting safety issues. • The effect of packaging geometry on RF heating uniformity and rate was studied. • The interlayer displacement (mixing) process on heating uniformity and rate in peanuts was evaluated during the RF heating. • The effect of particle sizes on heating efficiency in peanuts was determined. [ABSTRACT FROM AUTHOR]

• An electrode reversal device for radio frequency (RF) heating is proposed. • A multi-physics field numerical model incorporating the system is developed. • Optimal electric energy distribution when electrode width is 1.4 times product. • Electrode reversal during heating significantly improves RF heating uniformity. Radio Frequency (RF) heating technology exhibits potential advantages in the heat treatment of bulky products. The influence of electrode size on the RF heating performance by the electric field distribution, electromagnetic loss density, and temperature distribution was evaluated. An electrode reversal device was developed, facilitating the cyclic reversal of the positive and negative electrodes and the effect of electrode reversal was also investigated. Simulation results showed an optimal heating uniformity when the ratio of electrode to product width is 1.4. At that time, the influence of stray electric field between the positive electrode and the cavity on the electromagnetic energy was minimal. The variation in loss angle tangent caused by temperature change was the primary reason for the fluctuation of the electromagnetic-thermal energy conversion efficiency within the same radio-frequency field. The electrode reversal dramatically improved the heating uniformity in the direction of electromagnetic energy decay. The temperature uniformity index (TUI) can be reduced by 32.79 % to 75.41 % with the shorter reversal cycle, but the service life of the device was also curtailed due to more mechanical motions. Considering the stability of the equipment and the heating performance, the optimum reversal cycle was chosen to be 420 s. In this case, the maximum TUI didn't exceed 0.017, demonstrating better heating uniformity as compared with the commonly used for improving heating uniformity. In conclusion, a suitable electrode width and reversal cycle can effectively avoid the thermal offset effect of larger agricultural products during RF heating, thus improving the heating performance. [ABSTRACT FROM AUTHOR]

The effect of two food intrinsic factors (fat content, matrix structure) on the radio frequency (RF) inactivation of Salmonella Typhimurium and Listeria monocytogenes was investigated in dairy model systems: i.e., liquids with 0.08% and 5.9% fat and gels with 0.08% and 5.9% fat. In the liquid, higher fat content resulted in higher inactivation for both microorganisms. In gels, inactivation rate was higher with the lower fat content, while opposite behaviour occurred for L. monocytogenes above 70 °C. A gel matrix resulted in higher inactivation of S. Typhimurium, while complex temperature-dependent behaviour was present for L. monocytogenes. Sublethal injury was most significant for L. monocytogenes at 5.9% fat content and high temperatures. Overall, fat content and matrix structure impacted the microbial inactivation during RF heating and should be taken into account when designing novel RF heating food decontamination strategies. Radio frequency (RF) heating as a food processing technology has seen increased industrial application in recent years. The technology allows a more homogeneous heating of food products and also enables the treatment of low-moisture foods. The increased knowledge on the influence of fat content and food structure on RF thermal inactivation will lead to the development of improved and more efficient treatments. • Higher fat content increases RF inactivation at temperatures above 64 °C. • RF inactivation was higher in gelled than liquid matrices. • Sublethal injury was mainly seen in L. monocytogenes inactivation at 5.9% fat. [ABSTRACT FROM AUTHOR]

Radio frequency (RF) is a novel food processing technology, which has the advantages of strong penetration and uniform heating. The temperature of RF processing is typically not high (70–90 °C), which has little damage to the sensory quality of food and is very suitable for ready-to-eat foods for pasteurization and quality maintenance. Because of its relatively low temperature and suboptimal pasteurization effect, RF is often used in conjunction with other novel processing approaches to enhance its efficacy. This paper reviews the applications of RF in combination with additives, active packaging, conventional heat treatment, vacuum and other electromagnetic wave (EW) technologies in foods processing in the last five years. The mechanisms behind tissue integrity-induced changes in ready-to-eat, ready-to-heat, ready-to-cook, ready-to-use food texture (e.g., hardness, firmness) and corresponding changes in chemical composition were elucidated during novel assisted RF technologies compared to conventional heating methods. Future research regarding continuous industrial-scale production and innovative applications is required. [Display omitted] [ABSTRACT FROM AUTHOR]

In hazardous or microscale environments, it is valuable to have actuators that can be triggered without a direct connection to a power source and can exhibit site‐specific actuation. Thermal actuators use temperature to initiate motion, and prior reports use heat sources such as direct current (DC) power or light, which have drawbacks of a limited movement and complexity in design for selective actuation. It is previously shown that carbon nanomaterials show remarkable heating rates in response to applied radio frequency (RF) fields. Herein, a noncontact, site‐specific thermal actuation by using RF heating of carbon nanomaterials is demonstrated. The actuators based on two RF susceptors: carbon black tape and laser‐induced graphene (LIG), are shown. The actuator shows stable and reproducible heating and bending over repeated cycles. The heating and bending performance of actuators using Comsol Multiphysics is also simulated. By simply manipulating the field frequency, it is able to create site‐specific actuation in two different locations. As a proof of concept, a light emitting diode (LED) switch that can change colors at specific operating frequencies, where actuators are used as a barrier between lasers and receivers, is demonstrated. Such actuators have potential applications in soft robotics, and micromanipulation systems. [ABSTRACT FROM AUTHOR]

The isothermal curing kinetics of carbon nanotube loaded epoxy was investigated using rheometry and differential scanning calorimetry (DSC) at a range of temperatures. Rheo-kinetics was used to observe time-dependent rheological changes in elastic (G′) and viscous (G″) moduli, and complex viscosities of epoxy-CNT samples during isothermal curing. DSC measurements were also performed to monitor the curing reaction, in order to compare against the rheo-kinetic parameters. The Kamal-Sourour kinetic model describes the curing of the epoxy-CNT system for rheo-kinetics and DSC well. The activation energies of the curing reaction were found to be ∼36 kJ/mol and ∼33 kJ/mol using rheo-kinetics analysis and DSC, respectively. In addition, radio-frequency (RF) electromagnetic fields were used to heat and cure the epoxy-CNT sample; such heating techniques are valuable in a number of epoxy processing technologies. G ′, G ″, and complex viscosities of RF heated samples were measured to monitor RF-aided curing. This allows us to monitor the curing kinetics inside samples being heated by RF fields; the data indicate that RF-aiding curing is faster than curing rates for samples undergoing curing inside a measurement device such as a rheometer or DSC, because the heat generated is immediate and volumetric. Image 1 [ABSTRACT FROM AUTHOR]

The objectives of the study on a continuous flow hot air dryer combined with radio frequency heating at different temperatures (HA/RF) (38 °C, 42 °C, 46 °C, and 50 °C) in a large-scale process compared with conventional continuous flow hot air drying (HA) were (1) to investigate the drying characteristics, drying kinetics, and milling quality of the process and (2) to observe the cooking quality and compare the sensory differences of the cooked rice after treatment. The drying characteristics and moisture diffusivity showed that the higher the radio frequency (RF) heating temperature, the shorter the drying time. The specific energy consumption and energy cost decreased when the RF heating temperature increased. The optimal condition in terms of fissure percentage was HA/RF42. In addition, there were no significant differences in head rice yield and white rice color determination, amylose content, texture profiles, and pasting properties in all HA/RF treatments. In the triangle test, it was found that at least 6% of the population could perceive a difference between HA and HA/RF50. In conclusion, this study proposes the further development of the HA/RF drying process at low-temperature profiles and shows the great potential of RF technology for commercial drying in rice industry.

Disinfestation of insect pests is a crucial unit operation to save the quality of food grains during the storage. Several methods of disinfestation are available including chemical and non-chemical methods. However, the use of the chemical method is avoided because of its adverse effects on the environment and studies show that chemical methods have failed frequently in recent years. This paper reviews the recent applications of ionizing radiation, modified atmosphere, and dielectric heating for disinfestation of insect pests in stored grains. It is noted that the technologies mentioned have numerous advantages in applications, however, they also possess some inherent disadvantages that cause adverse effects to the grains being treated. To maximize treatment efficiency, the systematic integration of multiple non-chemical disinfestation methods with other unit operations is recommended. • Dielectric heating has an advantage of instantaneous treatment time. • Irradiation affects physio-chemical properties of grain. • Possibility of re-infestation exists after irradiation treatment. • Non-uniform temperature distribution in dielectric heating is major challenge. • Systematic integration of multiple non-chemical disinfestation methods is recommended. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Milk protein plays a crucial role in human diets. Thermal modification is one of the most widely used food processing techniques. Traditional heating methods used in food processing, especially for heat-sensitive products, may lead to unintended loss of quality. Therefore, it is urgent to preserve the nutritional value, taste, and appearance of milk as much as possible and to improve the utilization efficiency of thermal modifying heat energy during the thermal processing of dairy products. This review provides an up-to-date overview of studies focusing on the fundamental principles, features, and impacts on the structure and functional characteristics of dairy proteins. Furthermore, it provides insights into the current application status of five emerging thermal technologies: ohmic heating, microwave heating, radio frequency heating, infrared heating, and extrusion heating. Additionally, this review highlights the existing problems of these novel thermal technologies and presents potential solutions. These technologies modify protein structures, enhancing their functional and biological characteristics. At the same time, microwave heating is studied by most countries because of its simple operation and remarkable modification effect. Although microwave heating has the potential to be applied to large-scale industrial dairy processing, it is crucial to explore the characteristics of other technologies to broaden the thermal modifying methods. • The essence of most emerging thermal technology is electric heating. • The emerging technology directionally changes the secondary structure of protein. • Microwave treatment has great potential in reducing milk protein allergy. • There is the closest cooperation in microwave heating research among countries. [ABSTRACT FROM AUTHOR]