Because their perceived quality depends almost entirely on crunchiness: even minimal moisture absorption makes flakes and puffed cereals soggy, and also increases the risk of mould forming during storage.

Because fats tend to migrate through lower-performance films, causing stains, loss of aroma and, in the most critical cases, the transfer of unwanted flavours to the film itself. An adequate grease barrier, typically provided by laminates with PET or aluminium, prevents these effects throughout the whole shelf life.

The first three structures — BOPP/metallised PET/PE, BOPP/metallised PP and Paper/metallised PP — all offer a high barrier level and are suitable for high-speed flow pack packaging, but they differ in recyclability: the version with metallised PET/PE is a non-recyclable multi-polymer structure, while the versions based on metallised PP (as a film or laminated to paper) are designed for high recyclability, and are better suited to mass-market or organic/clean-label products that want to improve their sustainability profile. PET/ALU/PE stands apart: thanks to the aluminium it offers the highest barrier of all, but at the expense of recyclability, and is therefore reserved for products exported to hot and humid climates or for bars with a high fat and nut content, where the extra protection is essential.

Generally yes, but with a different approach for the two product families. For bars we recommend mono-PP, which is more stable and suited to the barrier and speed requirements of flow pack. For breakfast cereals both mono-PP and mono-PE can be considered, but the choice depends heavily on the customer’s packaging machine: mono-PE has a much narrower processing window at sealing temperatures, so it requires specific attention during set-up; if the packaging machine is not sufficiently performant or precise in its temperature control, the material may not run correctly. This assessment should always be made together with the technical department, also checking the customer’s machinery.