Function: Protection

This is often regarded as the primary functions of the packaging: to protect its contents from outside environmental effects, be they water, moisture vapor, gases, odors, microorganisms, dust, shocks, vibrations, compressive forces, etc., and to protect the environment from the product. This is especially important for those products such as toxic chemicals which may seriously damage the environment.In the case of the majority of food products, the protection afforded by the package is an essential part of the reservation process. For example, aseptically packaged milk and fruit juices in cartons only remain aseptic for as long as the package provides protection; vacuum-packaged meat will not achieve its desired shelf life if package permits oxygen to enter. In general, once the integrity of the package is breached, the product is not longer preserved.
Packaging also protects or conserves much of the energy expended during the production and processing of the product. For example, to produce, transport, sell and store 1kg of bread requires 1.4 MJ of energy. This means that each unit of energy in the packaging protects eleven units of energy in the product. While eliminating the packaging might save 1.4 MJ of energy, it would also lead to spoilage of the bred and a consequent loss of 15.8 MJ of energy.