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J Sci Food Agric. 2013 Sep;93(12):2939-44. doi: 10.1002/jsfa.6120. Epub 2013 Apr 16.

Triggering mechanisms for oxygen-scavenging function of ascorbic acid-incorporated whey protein isolate films.

Author information

1
Department of Food Science and Technology, University of California, Davis, CA 95616, USA.

Abstract

BACKGROUND:

Incorporation of ascorbic acid (AA) into whey protein isolate (WPI) films has been shown to increase the film's ability to protect foods from oxidation. The O₂-scavenging function of AA-WPI films could be triggered upon being placed in contact with food products. Several food-related factors hypothesized to act as triggering mechanisms for activating the O₂-scavenging function of AA-WPI films were investigated, including change of water activity (a(w)), pH and/or metal catalyst presence.

RESULTS:

Rate of O₂ scavenging of AA-WPI films was observed to most closely follow first-order kinetics. The film a(w) level was found to control the O₂-scavenging rate. At high a(w) levels, O₂ scavenging occurred at a desirably rapid rate. Food models with pH 7.4 produced the fastest O₂-scavenging rate. The slowest rate at pH 3.0 was due to the lower concentration of O₂-sensitive ascorbate monoanion. The presence of Cu²⁺ accelerated AA oxidation at high a(w) level.

CONCLUSION:

The desirable activation of oxygen scavenging in AA-WPI film at high a(w) and neutral pH in the presence of metal catalyst suggests that such AA-WPI films can be used to protect foods that have the highest vulnerability to oxidation.

KEYWORDS:

ascorbic acid; edible films; kinetics; oxygen scavenger; whey protein

PMID:
23450783
DOI:
10.1002/jsfa.6120
[Indexed for MEDLINE]

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