Maintaining the freeze thawing characteristics of tomato through development and evaluation of magnetic field‐assisted freezing system

This study was conducted to investigate the effect of application of developed electromagnetic field system on freezing characteristics and quality of whole frozen tomato fruit. The system was developed with an electromagnetic field generating apparatus for applying magnetic field in the range of 2.5 mT (0.025 kGauss) and 3.0 mT (0.030 kGauss) in the existing deep freezing system. Freezing experiments were conducted to analyze the freezing curve so as to determine the effect of electromagnetic field on effective freezing time and rate in comparison with ordinary freezing process. Sensory characteristics were evaluated on the basis of visual appearance, texture, and thawing loss after thawing of samples at room temperature. Results indicated that magnetic field resulted in complete freezing of tomato samples in much shorter period of time (220–260 min) as compared to ordinary freezing (1460 min) with prominent lowering of freezing point and extending degree of supercooling. Thawing loss was significantly (p < 0.05) lower for electromagnetically frozen samples. It was 0.02% for the tomato samples frozen under the effect of magnetic field as compared to control (1.73%). Electromagnetically frozen tomato samples exhibited freshness and textural characteristics in terms of hardness of cell structure as close to the fresh samples even upon thawing and thus may represent a veritable means to retain the quality of perishables for longer period of time. Novelty Impact Statement The application of magnetic field along with the existing freezing method results positively in enhancing the degree of supercooling and helped in reducing the damage to the food products caused by the formation of non-uniform and larger ice crystals while speeding up the freezing process. The samples frozen with applied magnetic field differed significantly from the samples frozen conventionally in terms of appearance, freshness, and thawing loss. The fast freezing controlled the ice nucleation, decreased the freezing period, and maintained the stability of size, shape, and distribution of ice crystals in the food product. Drip loss was observed to be 1.73% after thawing when tomatoes were frozen without the influence of magnetic field. By the application of magnetic field, it was reduced to 0.02% for the same samples under similar thawing conditions just after the completion of the freezing process.