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Shelf-life
of Whey-Protein-Coated Peanuts Analyzed by Static
Headspace Gas Chromatography
By
S.-Y. LEE and J.M.Krochta
Department of Food Science & Technology University of California, Davis, CA, 95616
Lipid
oxidation in peanuts results in ‘flavor-fade’ and off-flavor development.
Whey-protein-isolate (WPI)-based films have been found to be excellent oxygen
barriers. Thus, we hypothesized that WPI
films formed as coatings on peanuts would reduce the rate of peanut lipid
oxidation.
The
objectives of this study were to determine coated and uncoated peanut oxidation
in peanuts stored at ambient conditions.
Four different formulations of WPI-based coatings were used to coat the
peanuts. Besides an uncoated peanut
reference, controls were used to investigate the effects of other ingredients
in the coating formulation. The peanut
samples were stored in duplicate at ambient conditions for up to 68 weeks and
then analyzed using static-headspace gas-chromatography analysis of
hexanal.
The results
indicate that the coated samples were oxidized significantly slower than the
reference (uncoated peanuts); hence, the predicted shelf-life is longer for the
coated samples. The control samples also
showed a delay in oxidation.
The results
also indicate that the WPI coating coverage was incomplete and the coatings
suffered from some cracking and flaking.
Research continues on coating peanuts to achieve more complete (100%)
coverage and more durable coatings.
For more information on Dr. Krochta’s work and the Food Science and Technology Department at UC Davis, please visit Dr. Krochta's Web site - http://foodscience.ucdavis.edu/fst/faculty/KrochtaWeb/index.htm.