Theoretical And Experimental Study On Pressure Precooling Of Tomato

In this paper, the precooling effect of tomato in pressure precooling process was theoretical and experimental researched. Evaluation indexes for precooling effect are mainly half cooling time,7/8cooling time, uniformity and weight loss. The precooling effects under different precooling ways, different precooling temperature, different vent hole of carton and different palletizing styles of carton has analyzed.There are many factors, which affect the precooling effect. Precooling ways, precooling temperature, the vent diameters of carton and palletizing were chose to research in this thesis. Four different precooling ways of cold storage precoling,forceed air precooling,pressure precooling,water cooling;fourour different precooling temperatures of10℃,5℃,3℃,0℃Carton-packaged with six different vent diameters of3cm、4cm、5cm、6cm、7cm、8cm; Palletize three layers and three columns respectively between two kinds of carton with vent diameter of3cm and6cm were chose. The results imply that four kinds of cooling ways, water cooling was the best way, pressure precooling was secondary, but water precooling existed second time pollution and some fruits and vegetables were not suitable for water cooling, pressure pre-cooling was basically suitable for all fruits and vegetables, no pollution and little difference in precooling time and uniformity with water precooling, so it was proposed that use pressure precooling; Experimental investigations on tomato with different precooling temperature were conducted. The results imply that there is big difference between the precooling temperature0℃with5℃and10℃at the cooling time, cooling uniformity and weight loss, little difference with the precooling temperature3℃, further reducing the precooling temperature will receive little precooling effect. Based on the actual situation, it is suggested that the precooling temperature of tomato between0℃to3℃is appropriate; the pressure pre-cooling effect on tomato packaged by the vent hole of8cm is best, the half cooling time,7/8cooling time, cooling uniformity and weight loss is24min,60min,0.15, and0.79%, respectively; the vent hole of6cm is better than the vent hole of3cm in whole precooling effect, The half cooling time,7/8cooling time, cooling uniformity, weight loss of the third layer and the third column are45min,96min,0.18,0.72%and63min,115min,0.24,0.71%respectively, it is suggested that when palletizing should not be more than four layer four columns.