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2 pages, 151 KiB

Open AccessEditorial

Applications of Radio Frequency Heating in Food Processing

by Shaojin Wang and Rui Li

Foods 2023, 12(6), 1133; https://doi.org/10.3390/foods12061133 - 08 Mar 2023

Cited by 1 | Viewed by 1547

Abstract

Considering safety concerns regarding postharvest agricultural products or foods, environmental pollution caused by chemical fumigations, and increased international regulations to limit the use of fumigants, it is an extremely urgent task to develop novel and environmentally friendly physical alternatives to the postharvest control [...] Read more.

Considering safety concerns regarding postharvest agricultural products or foods, environmental pollution caused by chemical fumigations, and increased international regulations to limit the use of fumigants, it is an extremely urgent task to develop novel and environmentally friendly physical alternatives to the postharvest control of insect pests and pathogens [...] Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

Research

Jump to: Editorial

19 pages, 4559 KiB

Open AccessArticle

Radio Frequency Drying Behavior in Porous Media: A Case Study of Potato Cube with Computer Modeling

by Xiangqing Chen, Yu Liu, Ruyi Zhang, Huacheng Zhu, Feng Li, Deyong Yang and Yang Jiao

Foods 2022, 11(20), 3279; https://doi.org/10.3390/foods11203279 - 20 Oct 2022

Cited by 5 | Viewed by 1916

Abstract

To study the mechanism of heat and mass transfer in porous food material and explore its coupling effect in radio frequency (RF) drying processes, experiments were conducted with potato cubes subjected to RF drying. COMSOL Multiphysics^® package was used to establish a [...] Read more.

To study the mechanism of heat and mass transfer in porous food material and explore its coupling effect in radio frequency (RF) drying processes, experiments were conducted with potato cubes subjected to RF drying. COMSOL Multiphysics^® package was used to establish a numerical model to simulate the heat and mass transfer process in the potato cube and solved with finite element method. Temperature history at the sample center and the heating pattern after drying was validated with experiment in a 27.12 MHz RF heating system. Results showed the simulation results were in agreement with experiments. Furthermore, the temperature distribution and water vapor concentration distribution were correspondent with water distribution in the sample after RF drying. The water concentration within the food volume was non-uniform with a higher water concentration than the corner, the maximum difference of which was 0.03 g·cm⁻³. The distribution of water vapor concentration in the sample was similar to that of water content distribution since a pressure gradient from center to corner allowed the mass transfer from the sample to the surrounding in the drying process. In general, the moisture distribution in the sample affected the temperature and water vapor concentration distribution since the dielectric properties of the sample were mainly dependent on its moisture content during a drying process. This study reveals the mechanism of RF drying of porous media and provides an effective approach for analyzing and optimizing the RF drying process. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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16 pages, 4065 KiB

Open AccessArticle

Sterilizing Ready-to-Eat Poached Spicy Pork Slices Using a New Device: Combined Radio Frequency Energy and Superheated Water

by Ke Wang, Chuanyang Ran, Baozhong Cui, Yanan Sun, Hongfei Fu, Xiangwei Chen, Yequn Wang and Yunyang Wang

Foods 2022, 11(18), 2841; https://doi.org/10.3390/foods11182841 - 14 Sep 2022

Cited by 5 | Viewed by 1746

Abstract

In this study, a new device was used to inactivate G. stearothermophilus spores in ready-to-eat (RTE) poached spicy pork slices (PSPS) applying radio frequency (RF) energy (27.12 MHz, 6 kW) and superheated water (SW) simultaneously. The cold spot in the PSPS sample was [...] Read more.

In this study, a new device was used to inactivate G. stearothermophilus spores in ready-to-eat (RTE) poached spicy pork slices (PSPS) applying radio frequency (RF) energy (27.12 MHz, 6 kW) and superheated water (SW) simultaneously. The cold spot in the PSPS sample was determined. The effects of electrode gap and SW temperature on heating rate, spore inactivation, physiochemical properties (water loss, texture, and oxidation), sensory properties, and SEM of samples were investigated. The cold spot lies in the geometric center of the soup. The heating rate increased with increasing electrode gap and hit a peak under 190 mm. Radio frequency combined superheated water (RFSW) sterilization greatly decreased the come-up time (CUT) compared with SW sterilization, and a 5 log reduction in G. stearothermophilus spores was achieved. RFSW sterilization under 170 mm electrode gap reduced the water loss, thermal damage of texture, oxidation, and tissues and cells of the sample, and kept a better sensory evaluation. RFSW sterilization has great potential in solid or semisolid food processing engineering. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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12 pages, 3855 KiB

Open AccessArticle

Developing Radio-Frequency Roasting Protocols for Almonds Based on Quality Evaluations

by Ting-Yu Lian and Su-Der Chen

Foods 2022, 11(13), 1885; https://doi.org/10.3390/foods11131885 - 25 Jun 2022

Cited by 2 | Viewed by 1459

Abstract

Hot air roasting is a popular method for preparing almonds, but it takes a long time. We roasted almonds via dielectric heating using 5 kW, 40.68 MHz batch radio-frequency (RF) equipment and analyzed their quality and aroma using a gas chromatography/ion mobility spectrometer [...] Read more.

Hot air roasting is a popular method for preparing almonds, but it takes a long time. We roasted almonds via dielectric heating using 5 kW, 40.68 MHz batch radio-frequency (RF) equipment and analyzed their quality and aroma using a gas chromatography/ion mobility spectrometer and sensory evaluation. Almonds with an initial moisture content of 8.47% (w.b.) were heated at an RF electrode gap of 10 cm; the target roasting temperature of 120 °C was achieved at weights of 0.5, 1, 1.5, and 2 kg for 4, 3.5, 7.5, and 11 min, respectively; and the moisture content was reduced to less than 2% (w.b.). For comparison, 1 kg of almonds was roasted in a 105 °C conventional oven for 120 min. The darker color and lower moisture content, water activity, and acid value of the RF-roasted almonds were favorable for preservation. The aroma analysis using gas chromatography/ion mobility spectroscopy (GC–IMS) revealed that the aroma signal after roasting was richer than that of raw almonds, and principal component analysis (PCA) demonstrated that the aromas of roasted and commercial almonds were similar. The RF-roasted almonds presented a better flavor, texture, and overall preferability compared to commercial almonds. RF heating could be used in the food industry to roast nuts. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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12 pages, 2187 KiB

Open AccessArticle

Influence of Radio Frequency Heating on the Pasteurization and Drying of Solid-State Fermented Wolfiporia cocos Products

by Yu-Fen Yen and Su-Der Chen

Foods 2022, 11(12), 1766; https://doi.org/10.3390/foods11121766 - 15 Jun 2022

Cited by 3 | Viewed by 1785

Abstract

Rice bran and soybean residue are high in nutrients and active ingredients. They are used as media in the solid-state fermentation of Wolfiporia cocos. They not only reduce raw material costs, but also raise the economic value and applications of soybean residues [...] Read more.

Rice bran and soybean residue are high in nutrients and active ingredients. They are used as media in the solid-state fermentation of Wolfiporia cocos. They not only reduce raw material costs, but also raise the economic value and applications of soybean residues and rice bran. After 30 days of fermentation, the moisture content (w.b.) of the W. cocos product was approximately 40%, requiring it to be pasteurized and dried later. The objective of this research is to use radio frequency (RF) rapid heating technology to pasteurize and dry the solid-state fermented product. A 500 g bag of solid-state fermented W. cocos product took only 30 and 200 s at the RF electrode gap of 15 cm to pasteurize and reduce the moisture content (w.b.) below 15%, respectively; therefore, the methods can be used instead of the traditional 60 min autoclave sterilization and 100 min hot air drying at 45 °C. After RF treatment, the fermented W. cocos product was white, indicating that browning was prevented; the product contained 5.03% mycelium, 9.83% crude polysaccharide, 4.43% crude triterpene, 3.54 mg gallic acid equivalent/g dry weight (DW) of total polyphenols, and 0.38 mg quercetin equivalent/g DW of flavonoid contents and showed a good antioxidant capacity. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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13 pages, 5845 KiB

Open AccessArticle

Microstructure, Digestibility and Physicochemical Properties of Rice Grains after Radio Frequency Treatment

by Zhenna Zhang, Bin Zhang, Lin Zhu and Wei Zhao

Foods 2022, 11(12), 1723; https://doi.org/10.3390/foods11121723 - 13 Jun 2022

Cited by 5 | Viewed by 1810

Abstract

Radio frequency (RF) energy has been successfully applied to rice drying, sterilization, and controlling pests. However, the effects of RF treatment on the microstructure, physicochemical properties, and digestibility of rice have rarely been studied. This study investigated the alteration of a multiscale structure, [...] Read more.

Radio frequency (RF) energy has been successfully applied to rice drying, sterilization, and controlling pests. However, the effects of RF treatment on the microstructure, physicochemical properties, and digestibility of rice have rarely been studied. This study investigated the alteration of a multiscale structure, pasting, rheology, and digestibility of rice grains after the RF treatment. A microstructure analysis demonstrated that the RF treatment caused starch gelatinization and protein denaturation in rice grains with an increasing treatment time. After the RF treatment, indica and japonica rice (IR and JR) remained as A-type crystals, with the formation of an amylose–lipid complex. In contrast, the crystalline structure of waxy rice (WR) was disrupted. The RF treatment led to a decrease in crystallinity and short-range ordered structures. However, the DSC results indicated that the RF treatment enhanced the T_o, T_p, and T_c of IR and JR. The RF treatment resulted in an increase in the resistant starch (RS) of IR and JR, thereby reducing the digestibility. In addition, the pasting profiles of IR and JR after RF treatment were reduced with the increase in treatment time, while the RF-treated WR showed an opposite trend. The storage modulus (G′) and loss modulus (G″) of all samples after the RF treatment obviously increased compared to the control. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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14 pages, 1956 KiB

Open AccessArticle

Thermal Inactivation Kinetics and Radio Frequency Control of Aspergillus in Almond Kernels

by Yu Gao, Xiangyu Guan, Ailin Wan, Yuan Cui, Xiaoxi Kou, Rui Li and Shaojin Wang

Foods 2022, 11(11), 1603; https://doi.org/10.3390/foods11111603 - 29 May 2022

Cited by 2 | Viewed by 1700

Abstract

Mold infections in almonds are a safety issue during post-harvest, storage and consumption, leading to health problems for consumers and causing economic losses. The aim of this study was to isolate mold from infected almond kernels and identify it by whole genome sequence [...] Read more.

Mold infections in almonds are a safety issue during post-harvest, storage and consumption, leading to health problems for consumers and causing economic losses. The aim of this study was to isolate mold from infected almond kernels and identify it by whole genome sequence (WGS). Then, the more heat resistant mold was selected and the thermal inactivation kinetics of this mold influenced by temperature and water activity (a_w) was developed. Hot air-assisted radio frequency (RF) heating was used to validate pasteurization efficacy based on the thermal inactivation kinetics of this target mold. The results showed that the two types of molds were Penicillium and Aspergillus identified by WGS. The selected Aspergillus had higher heat resistance than the Penicillium in the almond kernels. Inactivation data for the target Aspergillus fitted the Weibull model better than the first-order kinetic model. The population changes of the target Aspergillus under the given conditions could be predicted from Mafart’s modified Bigelow model. The RF treatment was effectively used for inactivating Aspergillus in almond kernels based on Mafart’s modified Bigelow model and the cumulative lethal time model. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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14 pages, 3270 KiB

Open AccessArticle

Evaluation of Pilot-Scale Radio Frequency Heating Uniformity for Beef Sausage Pasteurization Process

by Ke Wang, Lisong Huang, Yangting Xu, Baozhong Cui, Yanan Sun, Chuanyang Ran, Hongfei Fu, Xiangwei Chen, Yequn Wang and Yunyang Wang

Foods 2022, 11(9), 1317; https://doi.org/10.3390/foods11091317 - 30 Apr 2022

Cited by 13 | Viewed by 2175

Abstract

Radio frequency (RF) heating has the advantages of a much faster heating rate as well as the great potential for sterilization of food compared to traditional thermal sterilization. A new kettle was designed for sterilization experiments applying RF energy (27.12 MHz, 6 kW). [...] Read more.

Radio frequency (RF) heating has the advantages of a much faster heating rate as well as the great potential for sterilization of food compared to traditional thermal sterilization. A new kettle was designed for sterilization experiments applying RF energy (27.12 MHz, 6 kW). In this research, beef sausages were pasteurized by RF heating alone, the dielectric properties (DPs) of which were determined, and heating uniformity and heating rate were evaluated under different conditions. The results indicate that the DPs of samples were significantly influenced (p < 0.01) by the temperature and frequency. The electrode gap, sample height and NaCl content had significant effects (p < 0.01) on the heating uniformity when using RF energy alone. The best heating uniformity was obtained under an electrode gap of 180 mm, a sample height of 80 mm and NaCl content of 3%. The cold points and hot spots were located at the edge of the upper section and geometric center of the sample, respectively. This study reveals the great potential in solid food for pasteurization using RF energy alone. Future studies should focus on sterilization applying RF energy and SW simultaneously using the newly designed kettle. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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11 pages, 3913 KiB

Open AccessArticle

Hot Air-Assisted Radio Frequency (HARF) Drying on Wild Bitter Gourd Extract

by Chang-Yi Huang, Yu-Huang Cheng and Su-Der Chen

Foods 2022, 11(8), 1173; https://doi.org/10.3390/foods11081173 - 18 Apr 2022

Cited by 4 | Viewed by 2062

Abstract

Wild bitter gourd (Momordica charantia L. var. abbreviata S.) is a kind of Chinese herbal medicine and is also a vegetable and fruit that people eat daily. Wild bitter gourd has many bioactive components, such as saponin, polysaccharide, and protein, and the [...] Read more.

Wild bitter gourd (Momordica charantia L. var. abbreviata S.) is a kind of Chinese herbal medicine and is also a vegetable and fruit that people eat daily. Wild bitter gourd has many bioactive components, such as saponin, polysaccharide, and protein, and the extract is used to adjust blood sugar in patients with diabetes. The objective of this study was to investigate simultaneous hot air-assisted radio frequency (HARF) drying and pasteurization for bitter gourd extract, and then to evaluate its effects on blood sugar of type II diabetic mice. The results showed that the solid–liquid ratio of the wild bitter gourd powder to water was 1:10 and it was extracted using focused ultrasonic extraction (FUE) for only 10 min with 70 °C water. Then, 1 kg of concentrated bitter gourd extract was mixed with soybean fiber powder at a ratio of 2:1.1. It was dried by HARF, and the temperature of the sample could reach above 80 °C in only 12 min to simultaneously reduce moisture content (wet basis) from 58% to 15% and achieve a pasteurization effect to significantly reduce the total bacterial and mold counts. Type II diabetic mice induced by nicotinamide and streptozocin (STZ) for two weeks and then were fed four-week feeds containing 5% RF-dried wild gourd extract did not raise fasting blood glucose. Therefore, the dried powder of wild bitter gourd extracts by HARF drying had a hypoglycemic effect. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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18 pages, 2841 KiB

Open AccessArticle

Effect of Load Spatial Configuration on the Heating of Chicken Meat Assisted by Radio Frequency at 40.68 MHz

by Sandro M. Goñi, Matteo d’Amore, Marta Della Valle, Daniela F. Olivera, Viviana O. Salvadori and Francesco Marra

Foods 2022, 11(8), 1096; https://doi.org/10.3390/foods11081096 - 11 Apr 2022

Cited by 7 | Viewed by 1680

Abstract

Food heating assisted by radio frequencies has been industrially applied to post-harvest treatment of grains, legumes and various kind of nuts, to tempering and thawing of meat and fish products and to post-baking of biscuits. The design of food processes based on the [...] Read more.

Food heating assisted by radio frequencies has been industrially applied to post-harvest treatment of grains, legumes and various kind of nuts, to tempering and thawing of meat and fish products and to post-baking of biscuits. The design of food processes based on the application of radiofrequencies was often based on rules of thumb, so much so that their intensification could lead significant improvements. One of the subjects under consideration is the shape of the food items that may influence their heating assisted by radiofrequency. In this work, a joint experimental and numerical study on the effects of the spatial configuration of a food sample (chicken meat shaped as a parallelepiped) on the heating pattern in a custom RF oven (40.68 MHz, 50 Ohm, 10 cm electrodes gap, 300 W) is presented. Minced chicken breast samples were shaped as cubes (4 × 4 × 4 cm³) to be organized in different loads and spatial configurations (horizontal or vertical arrays of 2 to 16 cubes). The samples were heated at two radiofrequency operative power levels (225 W and 300 W). Heating rate, temperature uniformity and heating efficiency were determined during each run. A digital twin of the experimental system and process was developed by building and numerically solving a 3D transient mathematical model, taking into account electromagnetic field distribution in air and samples and heat transfer in the food samples. Once validated, the digital tool was used to analyze the heating behavior of the samples, focusing on the most efficient configurations. Both experiments and simulations showed that, given a fixed gap between the electrodes (10 cm), the vertically oriented samples exhibited a larger heating efficiency with respect to the horizontally oriented ones, pointing out that the gap between the top electrode and the samples plays a major role in the heating efficiency. The efficiency was larger (double or even more; >40% vs. 10–15%) in thicker samples (built with two layers of cubes), closer to the top electrode, independently from nominal power. Nevertheless, temperature uniformity in vertical configurations was poorer (6–7 °C) than in horizontal ones (3 °C). Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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17 pages, 3089 KiB

Open AccessArticle

Temperature and Moisture Dependent Dielectric and Thermal Properties of Walnut Components Associated with Radio Frequency and Microwave Pasteurization

by Yuxiao Mao, Yujun Hao, Xiangyu Guan, Penghao Wang and Shaojin Wang

Foods 2022, 11(7), 919; https://doi.org/10.3390/foods11070919 - 23 Mar 2022

Cited by 5 | Viewed by 1942

Abstract

To provide necessary information for further pasteurization experiments and computer simulations based on radio frequency (RF) and microwave (MW) energy, dielectric and thermal properties of walnut components were measured at frequencies between 10 and 3000 MHz, temperatures between 20 and 80 °C, and [...] Read more.

To provide necessary information for further pasteurization experiments and computer simulations based on radio frequency (RF) and microwave (MW) energy, dielectric and thermal properties of walnut components were measured at frequencies between 10 and 3000 MHz, temperatures between 20 and 80 °C, and moisture contents of whole walnuts between 8.04% and 20.01% on a dry basis (d.b.). Results demonstrated that dielectric constants and loss factors of walnut kernels and shells decreased dramatically with raised frequency within the RF range from 10 to 300 MHz, but then reduced slightly within the MW range from 300 to 3000 MHz. Dielectric constant, loss factor, specific heat capacity, and thermal conductivity increased with raised temperature and moisture content. Dielectric loss factors of kernels were greater than those of shells, leading to a higher RF or MW heating rate. Penetration depth of electromagnetic waves in walnut components was found to be greater at lower frequencies, temperatures, and moisture contents. The established regression models with experimental results could predict both dielectric and thermal properties with large coefficients of determination (R² > 0.966). Therefore, this study offered essential data and effective guidance in developing and optimizing RF and MW pasteurization techniques for walnuts using both experiments and mathematical simulations. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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18 pages, 2885 KiB

Open AccessArticle

Effects of Radio Frequency Tempering on the Temperature Distribution and Physiochemical Properties of Salmon (Salmo salar)

by Rong Han, Jialing He, Yixuan Chen, Feng Li, Hu Shi and Yang Jiao

Foods 2022, 11(6), 893; https://doi.org/10.3390/foods11060893 - 21 Mar 2022

Cited by 5 | Viewed by 2461

Abstract

Salmon (Salmo salar) is a precious fish with high nutritional value, which is perishable when subjected to improper tempering processes before consumption. In traditional air and water tempering, the medium temperature of 10 °C is commonly used to guarantee a reasonable [...] Read more.

Salmon (Salmo salar) is a precious fish with high nutritional value, which is perishable when subjected to improper tempering processes before consumption. In traditional air and water tempering, the medium temperature of 10 °C is commonly used to guarantee a reasonable tempering time and product quality. Radio frequency tempering (RT) is a dielectric heating method, which has the advantage of uniform heating to ensure meat quality. The effects of radio frequency tempering (RT, 40.68 MHz, 400 W), water tempering (WT + 10 °C, 10 ± 0.5 °C), and air tempering (AT + 10 °C, 10 ± 1 °C) on the physiochemical properties of salmon fillets were investigated in this study. The quality of salmon fillets was evaluated in terms of drip loss, cooking loss, color, water migration and texture properties. Results showed that all tempering methods affected salmon fillet quality. The tempering times of WT + 10 °C and AT + 10 °C were 3.0 and 12.8 times longer than that of RT, respectively. AT + 10 °C produced the most uniform temperature distribution, followed by WT + 10 °C and RT. The amount of immobile water shifting to free water after WT + 10 °C was higher than that of RT and AT + 10 °C, which was in consistent with the drip and cooking loss. The spaces between the intercellular fibers increased significantly after WT + 10 °C compared to those of RT and AT + 10 °C. The results demonstrated that RT was an alternative novel salmon tempering method, which was fast and relatively uniform with a high quality retention rate. It could be applied to frozen salmon fillets after receiving from overseas catches, which need temperature elevation for further cutting or consumption. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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18 pages, 29673 KiB

Open AccessArticle

Effect of Large-Scale Paddy Rice Drying Process Using Hot Air Combined with Radio Frequency Heating on Milling and Cooking Qualities of Milled Rice

by Karn Chitsuthipakorn and Sa-nguansak Thanapornpoonpong

Foods 2022, 11(4), 519; https://doi.org/10.3390/foods11040519 - 11 Feb 2022

Cited by 13 | Viewed by 6036

Abstract

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) [...] Read more.

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. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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14 pages, 4529 KiB

Open AccessArticle

Effects of Radio Frequency Tempering on the Texture of Frozen Tilapia Fillets

by Jiwei Jiang, Fen Zhou, Caining Xian, Yuyao Shi and Xichang Wang

Foods 2021, 10(11), 2663; https://doi.org/10.3390/foods10112663 - 02 Nov 2021

Cited by 7 | Viewed by 1600

Abstract

Radio frequency (RF) tempering has been proposed as a new alternative method for tempering frozen products because of its advantages of rapid and volumetric heating. In this study, the texture of RF-tempered frozen tilapia fillets was determined under different RF conditions, the effects [...] Read more.

Radio frequency (RF) tempering has been proposed as a new alternative method for tempering frozen products because of its advantages of rapid and volumetric heating. In this study, the texture of RF-tempered frozen tilapia fillets was determined under different RF conditions, the effects of related factors on the texture were analyzed, and the mechanisms by which RF tempering affected the texture of the tempered fillets were evaluated. The results show that the springiness (from 0.84 mm to 0.79 mm), cohesiveness (from 0.64 mm to 0.57 mm), and resilience (from 0.33 mm to 0.25 mm) decreased as the electrode gap was increased and the power remained at 600 W, while the shear force increased as the power was increased for the 12 cm electrode gap (from 15.18 N to 16.98 N), and the myofibril fragmentation index (MFI) values were markedly higher at 600 W than at 300 W or 900 W (p < 0.05). In addition, the tempering uniformity had a positive effect on hardness and chewiness. The statistical analysis showed that the texture after RF tempering under different RF conditions correlated relatively strongly with the free water content, cooking loss, and migration of bound water to immobilized water. The decrease in free water and bound water migration to immobilized water resulted in a significant increase in cohesiveness and resilience. Full article

(This article belongs to the Special Issue Applications of Radio Frequency Heating in Food Processing)

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