To find a non-contact method that can reduce the weight loss of food during the vacuum cooling process

the mechanism of the water losing in tuber was studied firstly with the help of a high speed camera. Then

the effect of different depressurization schemes on the water loss in different tubers (with diameters of 27 mm，22 mm and 12 mm respectively) was studied based on the above conclusion. The results show that: 1) most of the lost water is launched out by the taylor bubble in the tube; 2) slowing the vacuum speed suitably while the total pressure is close to the flash point can reduce the weight loss significantly (the decreasing ratio was 72%); 3) using the tube with a smaller diameter can caused a higher weight loss when the pressure is close to the flash.