Application of Vacuum Freezing to Improve the Quality of Thawed Carrot Discs

Freezing is a good way for food preservation. In addition to the process effectiveness, modern food freezing techniques should guarantee the high quality of the products after freezing. This study concerns the application of low pressure for food freezing covering a specific temperature range named freezing critical zone. Vacuum freezing (VF) allows a fast freezing rate without the use of a cryogenic medium. The application of VF allowed a comparable freezing rate as air freezing at − 80 °C in the temperature range of about 2 to − 6 °C, which constitutes an advanced technology. Carrot discs with VF (from 2 to − 6 °C) were still of good quality by controlling the duration of the freezing critical zone, even with subsequent slow freezing (SF) (from − 6 to − 20 °C). Carrot samples frozen under different conditions were extensively compared by the results in mass loss, textural property, and microstructural changes of SEM, quantifying the freezing damage. The results showed that carrot discs subjected to the freezing procedure of VF + SF contributed to a comparable texture to that of fast freezing, minimal mass loss, as well as reduced microstructure destruction. Even in the case of increased sample size, which requires more intense freezing conditions, the carrot discs maintained their good quality attributes after VF + SF. In conclusion, the application of VF in the temperature range covering the freezing critical zone can be a promising approach for improving the quality of frozen food products.