Influence of chitosan on mechanical, thermal, barrier and antimicrobial properties of PLA-biocomposites for food packaging

The effect of chitosan (CH) concentration on the properties of biocomposites containing plasticized poly(lactic acid) (PLA) with tributyl o-acetyl citrate (ATBC) was studied both in respect with changes in properties and antifungal/antimicrobial activities. It was found that ATBC reduced brittlenes of PLA, the sheets and films obtained from plasticized PLA/CH biocomposites have satisfactory transparence, mechanical and improved thermal properties. The PLA/CH biocomposites are not toxics for germination of cucumber and radish seeds. Migration tests performed in two food simulants and one modified to avoid high temperatures which are near glass transition of PLA showed that such biocomposites are suitable materials for the packaging of non-fatty foods with a pH above 4.5 at refrigeration temperature. All prepared PLA-based materials showed good antifungal activity against Aspergillus brasiliensis ATCC 16404, Penicillium corylophilum CBMF1 and Fusarium graminearum G87 at the contact surface which increases by CH incorporation. As it concerns antimicrobial activity only biocomposites containing CH exhibit significant reduction in S. aureus and E. coli on the contact surfaces.