Meat is the most widely consumed and used type of food currently (Bao, Ertbjerg, Estevez, Yuan, & Gao, 2021). Chicken, as a white meat, is a healthy food source with rich nutritional compositions (da Silva, de Arruda, & Goncalves, 2017). Compared with the red meat, for example pork or beef, chicken has relatively lower contents of fat and cholesterol, indicating a healthier eating effect for consumers (Jaturasitha, Srikanchai, Kreuzer, & Wicke, 2008). As a commonly used method of preserving meat products, freezing can effectively maintain the freshness of the samples by inhibiting the action of bacteria and enzymes in a cryogenic environment (Zhang, Sun, Chen, Kong, & Diao, 2020). Moreover, before further processing, for example machine slicing or manual cutting, frozen chicken breast usually needs to be tempered to −5 to −2 °C (Bedane, Altin, Erol, Marra, & Erdogdu, 2018). Therefore, it is necessary to explore an appropriate tempering method to achieve rapid and uniform heating effect for frozen chicken breast.

The processes of conventional tempering methods, for example air tempering (AT) and water tempering (WT) (Wang, Guan, Mao, Li, & Wang, 2023), are achieved through convection and conduction heat transfer effects. Due to the characteristics of heat transfer media, the temperature rise starts from the surface boundary, resulting in the attenuation of heat transfer inside the material (Altin, Marra, & Erdogdu, 2022). The sharp decreases in heat transfer due to lower thermal conductivity of chicken samples often results in a longer tempering time leading to some loss in quality attributes (Erdogdu, Altin, Marra, & Bedane, 2017) and nutrient losses. In addition, the long-term metabolic activity of microorganisms might also lead to the production of substances harmful to human health in products (Jiang, Zhou, Xian, Shi, & Wang, 2021). The criteria for selecting the optimal tempering process are: efficiency, temperature uniformity, and the ability to retain the nutritional content and freshness of frozen food. In recent years, several new tempering methods have been explored to achieve this requirement, such as radio frequency (RF) tempering (Chen, He, Li, Tang, & Jiao, 2021; Han et al., 2022), high-voltage electrostatic field (HVEF) tempering (He, Liu, Nirasawa, Zheng, & Liu, 2013; Rahbari et al., 2018), microwave (MW) tempering (Miran & Palazoglu, 2019; Seyhun, Ramaswamy, Sumnu, Sahin, & Ahmed, 2009), and ohmic (OH) tempering (Chen et al., 2022).

RF tempering (RFT) is a dielectric heating method using electromagnetic waves with frequencies ranging from 10 to 300 MHz (Zhou & Wang, 2019). Ionic conduction and dipolar rotation are the major mechanisms in which the RF wave heats up materials (Mao, Wang, Wu, Hou, & Wang, 2021). Different from conventional tempering methods, RFT allows the material to achieve overall temperature rise without contacting the sample surface. RFT also has longer wavelength and larger penetration depth than MW tempering (MWT) (Jiang, Ling, Zhou, & Wang, 2020). With the advantage of volumetric heating, RFT has been used for different types of materials (Choi et al., 2017; Jiang, Wang, Guo, & Wang, 2021; Zhu, Li, Tang, Wang, & Jiao, 2019). Recognizing the existing problems (edge effect and thermal runaway) during RF tempering (Llave & Erdogdu, 2022), several studies have been conducted to explore different measures to the improve heating uniformity (Bedane et al., 2018; Dong et al., 2021).

The current situation recognizes that conventional and MW tempering methods are widely used in household applications. Many studies have shown that RFT has significant advantages over conventional tempering. Most RF heating systems used in tempering studies are industrial-scale systems, but there are just a few applications with small-scale RF heating systems (Tian, Guan, Li, Ramaswamy, & Wang, 2023) suitable for home tempering treatments. There are only limited studies focusing on the RF tempering treatment, which can be used for household applications and satisfy the requirements of rapid and uniform tempering. Besides, there are a few of studies (Li et al., 2021; Zhang et al., 2021) on improving heating uniformity in RFT treatments by using additional covering materials, which are easily available in household environments as surrounding media, such as crushed ice. Accordingly, effective treatments of crushed ice assisted RFT are of interest to explore for improving the tempering rate, heating uniformity and retaining nutritional composition of chicken breast samples for household applications.

The purpose of this study was (1) to explore the tempering processes and surface temperature distributions of frozen chicken breast with different dimensions tempered by a custom designed small-scale 50 Ω RF heating system, (2) to compare the tempering rate and heating uniformity of chicken breast surrounded by crushed ice under different processing parameters of the RF system and MW oven, and (3) to evaluate the changes of the quality parameters, including drip loss, color, pH values, and total volatile base nitrogen (TVBN) content in the samples under the selected tempering treatments.