INTECIN   20395
INSTITUTO DE TECNOLOGIAS Y CIENCIAS DE LA INGENIERIA "HILARIO FERNANDEZ LONG"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
INDIVIDUAL AND COMBINED PERFORMANCE OF NISIN AND POTASSIUM SORBATE SUPPORTED IN TAPIOCA STARCH EDIBLE FILMS
Autor/es:
C. BASCH, J. CARPENCO, R.J. JAGUS AND S. FLORES
Reunión:
Congreso; International Congress on Engineering and Food (ICEF 11).; 2011
Resumen:
Edible
films with antimicrobial activity based on preservative releasing
provide a promising form of active packaging systems applicable in food
processing. They allow a better efficiency in food protection as they
offer more stability on the antimicrobial agents, and ensure the
control of its release toward food.
The
objective of this research was to study the individual and combined
effect of nisin and potassium sorbate, supported in tapioca starch
edible films, on L. innocua and Zygosaccharomyces bailii, as well as the effect of antimicrobials on some physical and mechanical properties.
Films
were prepared by casting technique. The effect of the edible film as
antimicrobial barrier to external hazard as well as the diffusional
characteristics of the antimicrobials were studied. The physical
properties were evaluated through solubility test, water vapour
permeability (WVP), colour attributes, and mechanical characterization
by tensile strength and elongation at break.
Results
obtained showed that the starch based film itself could not inhibit
the bacterial or yeast growth at the film medium interface. On the
contrary, the starch films containing nisin or nisin/KS yielded a low
density of Wisteria growth at the film medium interface and a clear inhibition zone around the film disk (total diameter of inhibition: 2.00 and 1.70 mm for an initial disk diameter of 0.70 mm), showing antimicrobial diffusion to the solid medium.
The
barrier assay evaluated if the antimicrobials contained in the film
are available to act as a barrier for external microbial contamination.
Films without antimicrobials or individuals one allowed the Wisteria
growth. On the contrary, films containing nisin/KS showed a
bacteriostatic effect, reaching at the end of the storage a population
of 3.4 log cycle lower than the films without antimicrobials. In the
presence of Z. bailii, tested films allowed the yeasts
growth. However, nisin/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 in comparison with films without preservatives. It
was observed a decrease of tensile strength to around 0.62 MPa and an
increase of the elongation at break until 3.2, being nisin/KS films the
most extensible. The solubility in water was higher, 25-36%, when
antimicrobials were incorporated to film formulation. Contrarily, WVP
was not affected by the KS and/or nisin presence and it was determined a
WVP average value of 1.44 x 10-11 g / Pa m s. Colour
attributes of films showed a slight darkness for antimicrobial films
as was established by an increase of YI and b* values. Combined
nisin/KS films displayed the highest YI (13.6) and b* (7.1) parameters.
These
results revealed that the developed antimicrobial film could act as an
active packaging being a hurdle against microorganisms present in food
systems and as a barrier to further product contamination. In
addition, the antimicrobial agents might modify the physical and
mechanical properties.