The vacuum degree of 97 ~ 100kPa packaging conditions actually reduced packaging. Low fat foods are generally used for high moisture, e.g., whole milk powder. Vacuum-packed role is mainly to exclude oxygen, reduce or avoid fat oxidation, and can inhibit mold and other aerobic microorganisms. But can not completely prevent the vacuum packaging oxidation problems. Such as whole milk powder in the hot air is made by spray drying of milk powder particle contains many tiny air bubbles, using a vacuum pump removing the air in the container can be completed within a few seconds, the air particles outwardly diffusion it takes a few days. Further requirements can be prolonged storability whole milk powder, the vacuum vessel at 8.3 × 104Pa need more, such as the use of more than 0.5kg metal cans, can easily be deflated atmosphere.