The intent is (usually) to remove oxygen from the container to extend the shelf life of foods and, with flexible package forms, to reduce the volume of the contents and package. By reducing the oxygen residual contents, the growth of aerobic bacteria is limited and the shelf life can typically be extended by a factor of 5 to 10.
Additionally, vacuum packaging prevents evaporation of volatile components, protects the flavor and texture, and reduces freezer burn by protecting the food from the dry cold air. Different processes / technologies are commonly used.
Food processing includes all the transformation steps of raw ingredients into food, or of food into other forms. It processing typically takes clean, harvested crops or butchered animal products and uses these to produce attractive, marketable and often long shelf-life food products. Similar processes are used to produce animal feed.
Food processing covers a very wide range of applications where vacuum is often used for various properties.