On the use of different hydrocolloids as electrospun adhesive interlayers to enhance the barrier properties of polyhydroxyalkanoates of interest in fully renewable food packaging concepts

This paper compares the effect of adding different high barrier nanostructured interlayers with adhesive properties, made of electrospun whey protein isolate (WPI), pullulan, zein and zein blends with WPI and pullulan, to a polyhydroxyalkanoates material, specifically, polyhydroxybutyrate-co-valerate with a valerate content of 3% (PHBV3) in a multilayer form. The attained morphology, thickness and inherent permeability of the electrospun nanostructures played an important role on oxygen and water barrier properties of these multilayer systems, since both permeability values were only improved when fibrillar morphologies (pullulan and/or zein fibres) were obtained. More specifically, oxygen and water vapour permeability values were improved between 38–48% and 28–35%, respectively, in multilayer systems prepared by the addition of electrospun zein and/or pullulan nanofibres. However, the electrospun WPI nanostructures, exhibiting a beaded morphology, did not significantly decrease the water vapour and oxygen permeability values of the PHBV3-multilayer systems as did zein and pullulan (fibres). These results add new insight, to other previous studies, into the potential of this processing method for the development of biodegradable PHBV multilayer systems of significant interest in food packaging applications.