Effect of Vacuum Pre-cooling on the Circulation and Shelf Quality of Postharvest Baby Cabbage

To optimize the treatment conditions for vacuum pre-cooling of baby cabbage and maintain the fresh quality of postharvest baby cabbage, a central composite response surface experiment with two factors and three levels was conducted on the basis of analyzing the effects of different vacuum pre-cooling final temperature (0, 2 and 4 ℃) and different vacuum pre-cooling final pressure (400, 600, 800 and 1000 Pa) on the pre-cooling of postharvest baby cabbage. The results showed that compared with the control without pre-cooling and the pre-cooling group with final temperature of 0 ℃, the pre-cooling with final temperature of 2~4 ℃ at the final pressure of 600 Pa could better maintain the appearance quality of postharvest baby cabbage, inhibit the increase of respiratory rate and malondialdehyde (MDA) content. Under the condition of final temperature of 2 ℃, compared with the control without pre-cooling and the pre-cooling group with a final pressure of 1000 Pa, pre-cooling with final pressures of 400~800 Pa could also better maintain the appearance quality of postharvest baby cabbage, inhibit the increase of respiratory rate and MDA content. Further central composite response surface experiments showed that the optimal conditions for vacuum pre-cooling of postharvest baby vegetables were final temperature of 4.0 ℃ and final pressure of 600 Pa. The vacuum pre-cooling condition not only maintained good quality of postharvest baby vegetable, but also increased the content of soluble protein, total phenols, and ascorbic acid by 18.78%, 18.47% and 33.23%, respectively. Therefore, appropriate vacuum pre-cooling treatment is a highly potential commercialization technology that could effectively maintain the good quality of postharvest baby vegetable during circulation and shelf life.