Vacuum sealing is most useful for foods that need to remain moist. ... The process of vacuum sealing seals a plastic bag's contents through vacuum. Once the food is placed in a sealable bag, the air is removed by the vacuum sealer and the item remains fresh for a long time.
In vacuum cooking, meats are cooked at reduced pressure and temperature. In one vacuum technique, known as sous vide cooking, foods are cooked in their own juices, thus retaining their natural flavours and moisture. Cooking time is usually increased because of the low temperatures employed.