 INDIVIDUAL AND COMBINED PERFORMANCE OF NISIN AND POTASSIUM SORBATE SUPPORTED IN TAPIOCA STARCH EDIBLE FILMS

C. BASCH; J. CARPENCO; R.J. JAGUS ; S. FLORES

Atenas

Congreso; International Congress on Engineering and Food (ICEF 11).; 2011

National Technical University of Athenas, School of Chemical Engineering

Individual and combined effect of nisin (N) and potassium sorbate (KS), supported in tapioca starch ediblefilms, on Listeria innocua and Zygosaccharomyces bailii, as well as the effect of antimicrobials on somephysical and mechanical properties, were studied.Results obtained showed that the starch films containing N or N/KS yielded a clear inhibition zone aroundthe film, showing antimicrobial diffusion to the solid medium. The barrier assay showed that films withoutantimicrobials or individuals one allowed the Listeria growth. On the contrary, films containing N/KSshowed a bacteriostatic effect. In the presence of Z. bailii, teasted films allowed the yeasts growth. However,N/KS films showed a final yeast count of 1.3 log cycle lower than the film without antimicrobials.Regarding mechanical properties, individual or combined antimicrobials exerted a plasticizing effect incomparison with films without preservatives. It was observed a decrease of tensile stress to around 0.62 MPaand an increase of the elongation at break until 3.2, being N/KS films the most extensible. The solubility inwater was higher, 25-36%, when antimicrobials were incorporated. Contrarily, water vapor permeability(WVP) was not affected by antimicrobials presence and it was determined a average value of 1.44 x 10-9 g /Pa m s. Color attributes showed a slight darkness for antimicrobial films as was established by an increase ofYI and b* values. Combined N/KS films displayed the highest YI (13.6) and b* (7.1) parameters.These results revealed that the antimicrobial film developed could act as an active packaging being a hurdleagainst microorganisms present in food systems and to act as a barrier to further product contamination. Thefilms with combined preservatives presented the best perfomance. It must be remark that, despite theantimicrobial agents modified the physical and mechanical properties of the films, they maintained a suitablebehaviour as a packaging material.