Effect of Atomized Water Spray during Vacuum Pre-cooling on the Quality of Pakchoi during Low Temperature Circulation and the Shelf Life Period

This work aimed to study the effect of atomized water spray during vacuum pre-cooling on the quality of pakchoi during low temperature circulation and the shelf life period. Quality and nutritional parameters of pakchoi subjected to vacuum pre-cooling combined with atomized water spray were analyzed during simulated circulation for one day at (4 ± 1) ℃ and the shelf life period of five days at (20 ± 1) ℃. The results showed that the co-treatment not only decreased the pre-cooling time by 68%, but also reduced the water loss rate of pakchoi by 73.29% and the mass loss rate after the shelf life by 15.6% in comparison with vacuum precooling alone. The co-treatment also delayed the yellowing process, and maintained higher contents of titratable acids, soluble sugars, and soluble proteins in pakchoi. In addition, on the last day of shelf life, the contents of nitrite and malondialdehyde in the co-treatment group were decreased by 13.70% and 14.82%, respectively compared with the vacuum precooling group. To sum up, vacuum pre-cooling combined with atomized water spray could not only solve the problem of water loss caused by vacuum pre-cooling and shorten the pre-cooling time, but also delay the yellowing of leaves and maintain better nutritional quality of pakchoi.