Theoretical Simulation and Experimental Study on Effect of Vacuum Pre-Cooling for Postharvest Leaf Lettuce

Enhai Liu¹, Xiaobo Hu² and Shengyong Liu^1,

¹Key Laboratory of Renewable Energy of Ministry of Agriculture, Henan Agricultural University, Zhengzhou, China

²Department of Food Engineering, Henan University of Animal Husbandry and Economy, Zhengzhou, China

Cite this paper:
Enhai Liu, Xiaobo Hu and Shengyong Liu. Theoretical Simulation and Experimental Study on Effect of Vacuum Pre-Cooling for Postharvest Leaf Lettuce. Journal of Food and Nutrition Research. 2014; 2(8):443-449. doi: 10.12691/jfnr-2-8-3

Abstract

The effect of vacuum pre-cooling process on leaf lettuce was a complex process of heat and mass transfers. Based on the properties of leaf lettuce in vacuum pre-cooling process, an unsteady computation model was constructed to analyze the factors affecting vacuum pre-cooling. Some factors such as the pre-cooling temperature, pressure and quantity of the spray-applied water were verified throughout the experiment. The study showed that the measured and simulated values were basically the same, and the overall trend was similar. The lower the vacuum pressure, the greater the cooling rate lettuce and water loss rate. In this experiment, the water volume and pre-cooling pressure were the important factors during vacuum pre-cooling. This paper discovered that the quantities of leaf lettuce covered with water were equal to 4.211–5.977% of the total sample mass and the mass loss of the sample was 1.987–2.873%. Under pre-cooling pressure of 600, 1000, and 1500 Pa, the mass loss was 2.758, 2.701 and 1.929%. After that, the results of calculation indicated that the quantities of capture water of the water-catcher was 1.607–2.567 g, and the cooling capacity of the total sample was 3.722–5.946W in vacuum pre-cooling process. The results reveal that the model of leaf lettuce was fitted and it was confirmed by the experimental data.

Keywords:
theoretical simulation model leaf lettuce vacuum pre-cooling cooling capacity

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