Effects of Electromagnetic Heating on Quick Freezing

Kim, Jinse; Park, Jong Woo; Park, Seok-Ho; Choi, Dong Soo; Choi, Sung R.; Kim, Yong Hoon; Lee, Soo Jang; Yoo, Seon Mi; Han, Gui Jeung

doi:10.5307/jbe.2015.40.3.271

Cited by 3 publications

(2 citation statements)

References 25 publications

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“…The temperature immediately after this rise from the latent heat was considered as the freezing point, and the difference between nucleation temperature and the freezing point was considered as the supercooling degree (SD). To slowly lower the temperature of kimchi, a custom freezer (Sinhan freezing plant Co., Chungju, Republic of Korea) capable of stepwise control with 48 memories from 20 to −30 °C was used (Kim et al., 2015). The freezer temperature was decreased from 2 to −10 °C at 0.5 °C intervals.…”

Section: Methodsmentioning

confidence: 99%

Supercooling as a potentially improved storage option for commercial kimchi

Kim

Choi

Kim

et al. 2021

Journal of Food Science

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The supercooling degree (SD), which refers to the difference between the ice nucleation temperature and freezing point of kimchi, varies depending on the type of kimchi, manufacturer, recipe, and manufacturing season. The aim of this study is to investigate the major influencing factors for the supercooled storage of kimchi and to analyze the possibility of supercooled storage for commercial kimchi. Pearson correlation analysis determined that, in commercial kimchi manufactured between March and July 2018, the SD of kimchi correlated to the number of aerobic bacteria (P < 0.01), however, was not associated with lactic acid bacteria. Moreover, the ice nucleation temperature of saline solution inoculated with aerobic bacteria was reduced from –3.03 ± 0.04 to –6.18 ± 0.11 °C by 10 kGy gamma ray sterilization. Meanwhile, the ice nucleation temperatures of 1.8 kg of commercial red cabbage kimchi and 500 g of white cabbage kimchi manufactured in February 2020 were –3.93 ± 0.06 °C and −3.57 ± 0.06 °C, respectively, and they could be stored at –2.5 °C for 12 weeks without freezing. Additionally, supercooled storage of kimchi at –2.5 °C caused a fermentation delay effect compared to control storage at 1 °C, considering the acidity and amount of lactic acid bacteria. Therefore, if the number of aerobic bacteria is controlled during the manufacturing process of kimchi, supercooled storage at temperatures below −2.5 °C may extend the shelf life of kimchi. Practical Application We have shown that aerobic bacteria are the key influencing factor for ice nucleation of kimchi during supercooled storage. Aside from the initial sterilization process, fermentation of kimchi can also be delayed by lowering the storage temperature below −2.5 °C. Moreover, the method of direct cool refrigeration may have an industrial‐level application.

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Section: Methodsmentioning

confidence: 99%

Supercooling as a potentially improved storage option for commercial kimchi

Kim

Choi

Kim

et al. 2021

Journal of Food Science

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“…To prevent the surface from defrosting to fast via heat transfer from air to the food, a custom-built chamber with temperature control from -40 to 10℃ was used ( Figure 6(a); Kim et al, 2014;Kim et al, 2015). An RF generator (TX-20, ADTEC Plasma Technology Co. Ltd., Hiroshima, Japan) and an auto-matcher (TST-2720, TST Co., Sungnam, Korea) were used for the RF power source.…”

Section: Rf Thawing Methodsmentioning

confidence: 99%

Study of Radio Frequency Thawing for Cylindrical Pork Sirloin

Kim¹,

Park²,

Park³

et al. 2016

Journal of Biosystems Engineering

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Purpose: Radio frequency (RF) heating is a promising thawing method, but it frequently causes undesirable problems such as non-uniform heating. This can occur because of the food shape, component distribution, and initial temperature differences between food parts. In this study, RF heating was applied to the thawing of cylindrically shaped pork sirloin by changing the shape of electrodes and the surrounding temperature. Methods: Curved electrodes were utilized to increase the thawing uniformity of cylindrically shaped frozen meat. Pork sirloin in the shape of a half-circle column was frozen in a deep freezer at -70℃ and then thawed by RF heating with flat and curved electrodes. In order to prevent fast defrosting of the food surface by heat transfer from air to the food, the temperature of the thawing chamber was varied by -5, -10, and -20℃. The temperature values of the frozen pork sirloin during RF thawing were measured using fiber-optic thermo sensors. Results: After multiple applications of curved electrodes resembling the food shape, and a cooled chamber at -20℃ the half-cylindrically shaped meat was thawed without surface burning, and the temperature values of each point were similarly increased. However, with the parallel electrode, the frozen meat was partially burned by RF heating and the temperature values of center were overheated. The uniform heating rate and heat transfer prevention from air to the food were crucial factors for RF thawing. In this study, these crucial factors were accomplished by using a curved electrode and lowering the chamber temperature. Conclusions: The curved shape of the electrode and the equipotential surface calculated from the modeling of the parallel capacitor showed the effect of uniform heating of cylindrically shaped frozen food. Moreover, the low chamber temperature was effective on the prevention of the surface burning during RF thawing

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Recent advances in food processing by radio frequency heating techniques: A review of equipment aspects

Gao,

Wu,

et al. 2023

Journal of Food Engineering

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Effects of Electromagnetic Heating on Quick Freezing

Cited by 3 publications

References 25 publications

Supercooling as a potentially improved storage option for commercial kimchi

Supercooling as a potentially improved storage option for commercial kimchi

Study of Radio Frequency Thawing for Cylindrical Pork Sirloin

Recent advances in food processing by radio frequency heating techniques: A review of equipment aspects

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