Protein or carbohydrate films. A glassy type of material will not allow the passage of large flavour molecules. Lipid films --> The flavour is relatively non-polar, which means that a lipid may not be a good choice. It will absorb the flavour and readily transfer it to the air. Composites --> The granule is very small, so applying a composite film would be difficult, as it is difficult to get these defect-free in thinner films