Background: The thawing process is regarded as an essential step before the consumption of frozen foods. This study aimed to evaluate the possibility of ultrasound thawing of frozen red radish and to explore the characteristics of ultrasound thawing. The influence of low-frequency ultrasound (LFU) on the thawing efficiency of frozen red radish cylinders in air and water mediums was investigated. The effects of different ways of thawing, including air thawing (AT), water thawing (WT), refrigeration thawing (RT), ultrasound-assisted water thawing (UWT), and microwave thawing (MT) on the thawing time and quality of radish samples was studied.
Results: The results showed that thawing time decreased remarkably in air and water mediums assisted by LFU. As the LFU power level increased, the thawing time decreased and the value of the drip loss increased. The firmness of thawed radish samples also decreased significantly compared with the fresh samples. Microwave thawing had the highest thawing rate, but the microstructure of MT radish samples was damaged severely, resulting in the highest drip loss, and the lowest firmness, and vitamin C content. In comparison with the AT, WT, and RT, a significant reduction in thawing time could be achieved for UWT (P < 0.05). Ultrasound-assisted water thawing exhibited the highest retention of color and vitamin C, and a lower destructive effect on the microstructure.
Conclusion: The results showed that LFU could be used as an efficient method to facilitate the thawing process of frozen red radishes, and better preserve the color, vitamin C, and microstructure of the final product. © 2020 Society of Chemical Industry.
Keywords: microwave; scanning electron microscopy; thawing; ultrasound.
© 2020 Society of Chemical Industry.