Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) films for food packaging: Physical-chemical and structural stability under food contact conditions
The objective of the present article is to bring new insights into the relationships between the structural and physical-chemical stability and the inertness of PHBV films with respect to the targeted food packaging application. It is concluded from overall migration tests that PHBV films can be used as food contact materials for any type of food. Functional properties of PHBV films (mechanical properties and water vapor permeability) were also very stable after contact at 40°C during 10 days with all food simulating liquids tested (water, acetic acid 3% (w/v), ethanol 20% (v/v), and iso-octane), except with ethanol 95% (v/v). Ethanol 95% (v/v) was identified as the worst case for PHBV films, with a high sorption value and an increase in the water vapor permeability. This was mainly explained by a significant plasticizing effect, together with a decrease in both the molecular weight and the crystallinity degree of PHBV films. From an industrial point of view, it allows assessing that the packaging functions of PHBV are fulfilled all over the food supply chain.