Antimicrobial and barrier properties of LDPE films containing imazalil and EDTA

Imazalil and ethylenediamine-tetraacetic acid (EDTA) were incorporated into low-density polyethylene (LDPE) aimed at producing antimicrobial packaging films for foodstuffs. Moulded plates (thickness 2 mm) containing 5% of EDTA inhibited Bacillus subtilis, whereas 0.05-0.25% of imazalil had strong activity against Aspergillus niger. Further tests for antimicrobial activity, migration and oxygen and water vapor barrier properties were carried out using biaxially stretched LDPE films containing different combinations of both substances. The addition of imazalil and EDTA increased the oxygen transmission rates and water vapor permeabilities, although the effects with imazalil films were not as significant. Transparency of the EDTA containing films decreased rapidly as a function of added EDTA, whereas imazalil films were optically faultless. Total migration into 3% acetic acid and 10% ethanol was below 4 mg/dm(2). Although imazalil retained its activity against A. niger on a high level (inhibition zones >30 mm), the activity of EDTA was gone. None of the samples inhibited Escherichia coli.