València Parc Tecnològic
Calle Gustave Eiffel, 4
In the last years, the Technology Plastics Centre, AIMPLAS, has been developing active packages with antioxidant properties and good thermal and mechanical resistance properties. This packaging is manufactured through co-injection moulding and has been used for the following products: fish, sauces, meat, cheese and fruit and vegetable.
There are two fundamental aspects in material selection in order to obtain these active packages. On the one hand, structures with oxygen barrier materials. On the other hand, packages compatible with sterilisation techniques, which these packages will have to undergo.
When choosing structural and sealing material, it has to be taken into consideration which one is the most rigid and will withstand sterilisation temperatures. In this line on work AIMPLAS has used polypropylene (PP) and EVOH (Ethylene-Vinyl Alcohol Copolymer) as barrier towards gases.
Additives with antioxidant properties which are already in the market are evaluated before making the choice. The main antioxidant systems consist on oxygen scavengers and natural antioxidants.
The following criteria has to be kept in mind when deciding which additives are going to be used: ease of activation and effectiveness, compatibility and stability at high temperatures, commercial availability and suitability to manufacturing packages coming into contact with food.
Additives prevent degradation of fatty compounds which cause food rancidity and spoilage after preserving processes: thermal sterilisation, high pressure sterilisation, modified atmosphere packaging and pasteurisation. They also help to dissipate and minimise residual oxygen after treatments.
A plastic material which brings together all properties necessary for optimum preserving of perishable foodstuff, is rare. As a consequence, the introduction of multilayer structures is needed. Co-injection moulding is a good option to obtain these structures. This process main characteristic is the capacity of completely encapsulating an injection moulded material inside another one.
This process favours the introduction of barrier materials in injection moulded packages, so that they can compete in food preserving with other materials such as metal or glass.