Effects of dehydrofreezing conditions on carrot β-carotene and kinetics of β-carotene change in dehydrofrozen carrots during storage

Abstract

Dehydrofreezing is a food freezing method in which the foods are partially dehydrated before freezing. In this study, carrots were frozen with convective (-30,-35,-40oC and 2 m/s airflow) and cryogenic methods after dehydrating them by different methods (osmotic dehydration, convective and vacuum drying). The effects of dehydration method, freezing conditions and storage time on β-carotene amounts of dehydrofrozen carrots and the changes in β-carotene content of dehydrofrozen carrots during storage for six months at-20oC were investigated. The findings obtained in this study showed that the reaction representing the carotene change in the storage process took place in accordance with the first-degree kinetic model. The reaction rate constants (k) were affected by freezing conditions, and the k value decreased as the freezing temperature decreased. The β-carotene losses were less in the storage process in the cryogenically frozen carrots compared to those frozen by the convective method. As the freezing temperature decreased, the half-life period increased.