Changes in total vitamin C content in 5 vegetables (paprika, spinach, parsley, broccoli, and pea) were investigated after the application of different food-processing techniques such as freeze-drying (FD), air-drying (AD), retort sterilization (RT). Drying characteristics such as rehydration and color of the vegetables were also evaluated. Among the 3 processing techniques, FD resulted in the highest vitamin C retention ratio in the vegetables. The rehydration ratios of the dried vegetables were determined after the vegetables were immersed in hot water at 80℃ for30min. The rehydration ratios obtained after FD were higher than the corresponding ratios obtained after AD. Moreover, the appearances of the FD-treated vegetables after rehydration were almost the same as those of the fresh vegetables. The degree of color difference between the fresh vegetables and the FD-treated vegetables was lesser than that between the fresh vegetables and the AD-treated vegetables. These findings confirmed that FD was the best method for processing of food items.
