Abstract
The objective of this study was to investigate the processing parameters and quality of carrots under sequential infrared (IR) dry-blanching and (1) hot air drying (IRB-HAD), (2) infrared drying (IRB-IRD), and (3) Infrared-hot air drying (IRB-IRHAD). Water blanching at 90oC was used for comparison. The quality of dried carrot was evaluated based on vitamin C content, rehydration ratio, color, shrinkage and hardness. Applying IR dry-blanching for 15 min resulted in the reductions of about one log in peroxidase (POD) activities and 54 % in moisture reduction. A notable change in the surface color and retention of vitamin C were obtained with IR blanching. IRB-IRD and IRB-IRHAD had higher drying rates and higher quality. The recommended processing parameters for IRB-IRHAD are IR blanching for 15 min, followed by IR drying to a moisture content of 30–40 % wet basis (w.b.), and then finished by HA drying to a targeted MC (8 % w.b.).
