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2006 IFT Poster Presentation (PDF)
WPI film/coating with oxygen scavenging function by incorporation of ascorbic acid
Author
T.
Janjarasskul, J. M. Krochta; University of California, Davis, CA
Justification:
At present, residual oxygen in a package headspace can be removed by an
oxygen absorbing sachet, which could be harmful if swallowed by the
consumer, or by a chemically active plastic packaging film, which is
difficult to recycle. An edible, oxygen-absorbing film would avoid these
disadvantages.
Objective:
The objective of our research was to assess the oxygen-scavenging
potential of an edible whey protein isolate (WPI) film incorporating
ascorbic acid (AA).
Methods:
AA at 0.05M, 0.1M, or 0.2M concentration was added to 5% (w/w)
heat-denatured WPI film-forming solutions with WPI:glycerol ratio of
1:1, 1:0.8, or 1:0.667. The pH of solutions was then adjusted to 3.5
(below pKa1 of AA), in order to stabilize AA against
oxidation, before casting on Teflon casting plates. The mechanical
properties and oxygen permeabilities of films were measured, using
INSTRON and OX-TRAN instruments, respectively. Activation of the
oxygen-scavenging function of the AA-incorporated films was accomplished
by adjustment of the films to pH ≥ 7.Oxygen-scavenging ability of
AA-incorporated WPI films was determined by measuring residual oxygen in
the headspace of a high-barrier container, using GSA, gas stream
analyzer.
Results:
Lowering film-forming-solution pH to 3.5 without AA increased film
tensile strength, decreased % elongation, increased elastic modulus and
decreased oxygen transmission rate. Adding AA before adjustment of
film-forming solution pH to 3.5 increased film elongation and
flexibility and further reduced oxygen permeability at each WPI:glycerol
ratio. AA-containing films adjusted to pH ≥ 7 demonstrated oxygen
absorption proportional to AA content and consistent with theoretical
oxygen-scavenging capacity.
Significance:
The demonstrated oxygen-scavenging function, improved oxygen barrier and
acceptable mechanical properties of AA-incorporated films indicates
potential commercial usefulness