Investigation of the effect of oscillating magnetic field on fresh-cut pineapple and agar gel as a model food during supercooling preservation

Authors: KANG, T. - University Of Hawaii; HER, J.Y. - Mokpo National University; HOPTOWIT, R. - University Of Hawaii; Wall, Marisa; JUN, S. - University Of Hawaii

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2019
Publication Date: 11/1/2019
Citation: Kang, T., Her, J., Hoptowit, R., Wall, M.M., Jun, S. 2019. Investigation of the effect of oscillating magnetic field on fresh-cut pineapple and agar gel as a model food during supercooling preservation. Transactions of the ASABE. 62(5): 1155-1161. https://doi.org/10.13031/trans.13285.
DOI: https://doi.org/10.13031/trans.13285

Interpretive Summary: During the process of freezing foods, the formation of ice crystals results in mechanical damage to food structure, leading to irreversible changes in food quality and texture. Supercooling is the phenomenon where the temperature of a food material is cooled below its freezing point without ice crystal formation, thereby completely avoiding freezing damage. In the present study, the effect of an oscillating magnetic field (OMF) on supercooling of fresh-cut pineapple was investigated. The pineapple was preserved in a supercooled state at -7°C and maintained for 14 days with the presence of the OMF, whereas the untreated sample was spontaneously nucleated within 24 hours. Supercooling effectively prolonged the shelf-life of fresh-cut pineapples with ensured freshness without freezing damage. The results suggest that the developed OMF technology could inhibit ice nucleation during supercooling preservation and can be utilized to preserve fresh-cut fruits at subzero temperature while ensuring the quality of foods.

Technical Abstract: In the present study, the effect of an oscillating magnetic field (OMF) on supercooling of fresh-cut pineapple and agar gel was investigated. The pineapple was preserved in a supercooled state at -7°C and its supercooled state was maintained for 14 days with the presence of the OMF, whereas the untreated sample was spontaneously nucleated within 24 hours. Agar gel was prepared as equivalent to the soluble solid content of pineapple and showed a comparable supercooling behavior when exposed to the similar OMF exercising protocols for pineapple. Examination of microstructures clarified that the cellular damage caused by ice crystal formation was not found in the supercooled pineapple and agar gel, implying that the OMF successfully inhibited ice nucleation during supercooling. The weight losses of pineapple samples preserved in the refrigeration, freezing, and supercooling for 14 days were determined to be 7.3, 23.8, and 0.8%, respectively. Furthermore, the visual appearance demonstrated that the supercooling preservation effectively prolonged the shelf-life of pineapple without freezing damages. The results suggest that the developed OMF technology could inhibit ice nucleation during supercooling preservation and can be utilized to preserve fresh-cut fruits at subzero temperature while ensuring the quality of foods. In addition, the solid model food could be used as a substitute for prediction of the supercooling behavior of food products.