New types of proactive bio-based packaging material for grated, sliced and whole cheeses have been developed. On the basis of polyactides (PLA) and chitosan, the newly developed materials have further undergone modification procedures with the aid of plasma coating or nanoclay incorporation.
Provision has been made for the problem of mould growing at the surface of the cheese with the addition of preservatives encapsulated in cyclodextrines (CDs). This innovation of adding preservatives in CDs into a bio-based material could also be transferred to other packaging materials.
The new packaging concept involves PLA, preservatives encapsulated into CD, high capacity oxygen scavengers, chitosan-bioactive natural polymer for modification of PLA packaging materials, nanoclay and plasma coating. In comparison to other conventional materials the novel bio-packaging can be offered at a very competitive price.
Part of the project results involved production of PLA/nanoclay films that display low permeability to oxygen and water vapour unlike fully exfoliated films. There were two ways of production of nanoclay films. One is by compounding the material with nanoclay and another is by coating the material with multi-layers of nanoclay.
Nanoclays were added to various PLAs, both “flexibilised” and “unflexibilised” and extruded into a film by means of a pilot plant-scale twin-screw extruder. It was shown that this combination in dry form improved the thermal stability of PLA and nanoclay was compounded with acceptable appearance.
Analysis results showed that nanoclay compounding can reduce permeability, yet the desired targets were not reached in the case of nanoclays with “flexibilised” PLA. Critical factors that affect the permeability reduction in PLA films include processing conditions, extruder characteristics, and selection of the most suitable type of nanoclay.
Incorporation of nanoclays into the PLA films may positively influence properties by facilitating release of a cyclodextrin-encapsulated antimicrobial within the films. Further investigation and confirmation of this finding may play a significant role in future applications of food packaging.
SÖDERGÅRD, Anders (PhD)
Head of Research
Source: CORDIS-offer 2293 Jan. 02, 2006.