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Diffusion of oxygen in cork.

Authors
  • Lequin, Sonia
  • Chassagne, David
  • Karbowiak, Thomas
  • Simon, Jean-Marc
  • Paulin, Christian
  • Bellat, Jean-Pierre
Type
Published Article
Journal
Journal of Agricultural and Food Chemistry
Publisher
American Chemical Society
Publication Date
Apr 04, 2012
Volume
60
Issue
13
Pages
3348–3356
Identifiers
DOI: 10.1021/jf204655c
PMID: 22369138
Source
Medline
License
Unknown

Abstract

This work reports measurements of effective oxygen diffusion coefficient in raw cork. Kinetics of oxygen transfer through cork is studied at 298 K thanks to a homemade manometric device composed of two gas compartments separated by a cork wafer sample. The first compartment contains oxygen, whereas the second one is kept under dynamic vacuum. The pressure decrease in the first compartment is recorded as a function of time. The effective diffusion coefficient D(eff) is obtained by applying Fick's law to transient state using a numerical method based on finite differences. An analytical model derived from Fick's law applied to steady state is also proposed. Results given by these two methods are in close agreement with each other. The harmonic average of the effective diffusion coefficients obtained from the distribution of 15 cork wafers of 3 mm thickness is 1.1 × 10(-9) m(2) s(-1) with a large distribution over four decades. The statistical analysis of the Gaussian distribution obtained on a 3 mm cork wafer is extrapolated to a 48 mm cork wafer, which length corresponds to a full cork stopper. In this case, the probability density distribution gives a mean value of D(eff) equal to 1.6 × 10(-9) m(2) s(-1). This result shows that it is possible to obtain the effective diffusion coefficient of oxygen through cork from short time (few days) measurements performed on a thin cork wafer, whereas months are required to obtain the diffusion coefficient for a full cork stopper. Permeability and oxygen transfer rate are also calculated for comparison with data from other studies.

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