INVESTIGATION OF THE EFFECT OF OSCILLATING MAGNETIC FIELD ON FRESH-CUT PINEAPPLE AND AGAR GEL AS A MODEL FOOD DURING SUPERCOOLING PRESERVATION

摘要

In this study, the effect of an oscillating magnetic field (OMF) on the supercooling of fresh-cut pineapple and agar gel was investigated. The pineapple was preserved in a supercooled state at -7 degrees 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 h. Agar gel was prepared as equivalent to the soluble solids content of pineapple and showed a comparable supercooling behavior when exposed to a similar OMF treatment. Examination of the microstructures showed that cellular damage due to ice crystal formation did not occur in the supercooled pineapple and agar gel, implying that the OMF successfully inhibited ice nucleation during supercooling. The weight losses of pineapple samples preserved with refrigeration, freezing, and supercooling for 14 days were determined to be 7.3%, 23.8%, and 0.8%, respectively. Furthermore, the visual appearance showed that supercooling effectively prolonged the shelf-life of pineapple without freezing damage. The results suggest that the developed OMF technology can inhibit ice nucleation during supercooling and can be used to preserve fresh-cut fruits at subzero temperature while ensuring the food quality. In addition, a solid model food could be used as a substitute for predicting the supercooling behavior of food products.