Ideally, during storage a food product will not deteriorate. However, usually products need to be protected against loss of quality caused by external factors.

First of all the packaging must provide physical (mechanical) protection. It should remain undamaged during transportation from manufacturer to end user. Damage caused by sharp objects or rough treatment must be avoided.

In addition to this mechanical protection, the effect of other external factors must be limited. The, what are called, barrier properties of the material should be sufficiently high to prevent the absorption of moisture, and to provide protection against foreign odours. Like all foodstuffs with a high fat content, cocoa and chocolate easily acquire foreign odours, i.e. become tainted, leading to unacceptable off-flavours. The absorption of moisture may lead to a moisture content (water activity) that enables the growth of micro-organisms. It may also cause other problems, such as sugar bloom on chocolate.

Clearly, is it very important that the packaging material is both gas and watertight. Gas-tightness is important in order to preserve the aroma and to exclude oxygen that leads to oxidation. To prevent oxidation reactions, which are accelerated by light, chocolate products are best stored in the dark. For this purpose, packaging material is very effective.