Effect of vacuum cooling on postharvest quality of chinese cabbage

Abstract

This research aimed to study the optimum parameter of the vacuum cooling process for Chinese

 cabbages with initial core temperatures of 20-23°C to obtain the final temperature of 4±1°C, and to study the quality of Chinese cabbages during storage. The experiment was conducted by using precooled trimmed Chinese cabbages packaged in perforated polyethylene bags using vacuum cooling. The process parameters were set by using the final pressures of 5.5, 6.0 and 6.5 millibar with 3 holding periods: 20, 25 and 30 minutes. The results showed that the optimum parameter of the vacuum cooling process for Chinese cabbages was at the final pressure of 6.0 millibar with the holding time of 25 minutes. The total cooling cycle time was 38 minutes and the electrical energy consumption was 5.8 kWh. The calculated cost of electricity was 0.04 Baht/kilogram of fresh weight. During the vacuum cooling process with this optimum parameter, the Chinese cabbages had a weight loss of 2.75%. These vacuum-cooled Chinese cabbages were then stored at 4°C with 80-85 % RH. The results showed that the vacuum-cooled Chinese cabbages had better appearance, longer storage life, and lower percentage of weight loss than the non-vacuum-cooled produce (P<0.05). However, the vacuum cooling process had no effect on leaf color, total chlorophyll content, vitamin C content, and total soluble solids (P>0.05).