Physical Characterization and Manufacturing of Frozen Meal Kit Shredded Radish Using Various Freezing and Thawing Conditions

This study was conducted to find the optimal freezing and thawing conditions for shredded radish (0.5×0.5×5 cm), which was frozen by conventional slow freezing (−25°C), or individual quick freezing (air blast freezing, −25°C, and −35°C). The frozen shredded radish was thawed using natural air convection thawing (25°C), running water thawing (18°C), and refrigeration thawing (4°C). The freezing and thawing were stopped when the core temperature reached −20°C and 4°C, respectively. The freezing time for air-blast freezing (7 min) was faster than conventional slow freezing, and the thawing time was faster in the order of running water thawing, natural air convection thawing, and refrigeration thawing. The pH of the radish increased after freezing and thawing. But no consistent trend of pH or °Brix as per the variance in thawing conditions was observed. Moreover, there was no significant difference seen in the moisture content. The thawing loss was affected by thawing rather than freezing. The hardness of the radish decreased after being subjected to all the freezing and thawing conditions. However, air blast freezing (−35°C) was most similar to the raw radish. The nutritional aspects of the air blast freezing (−35°C) and running water thawing samples were most similar to that of the raw radish (vitamin C contents, antioxidant activity, and total phenol contents). The sensory attributes of texture, visual form, and taste showed high scores in the raw material, running water thawing, and refrigeration thawing samples, respectively. It was observed from these results that the thawing conditions had a greater effect on radish qualities than the freezing conditions. Also, based on these results, we recommend that a combination of air blast freezing (−35°C) and running water thawing (18°C) could maintain the quality of shredded radish.