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The influence of diffusion and solubility on the reaction of oxygen in compact food

Der Einfluss von Diffusion und Löslichkeit auf die Reaktion von Sauerstoff mit kompakten Lebensmitteln
: Heiss, R.; Schrader, U.; Reinelt, R.

Linko, P.:
Food process engineering. Vol. 1: Food processing systems
London: Applied Science Publishers, 1980
ISBN: 0-85334-896-0
International Congress on Engineering and Food <2, 1979, Espoo>
Conference Paper
Fraunhofer IVV ()

Calculation of the shelf-life on an oxygen sensitive food in a package of distinct oxygen permeability is possible if the time dependent oxygen tolerance is known. Additionally, with compact food the local oxygen concentration differences have to be considered. To render the calculation of the distribution of dissolved oxygen and of the oxidation products possible, a CMC-gel has been used as a model in which the diffusion-constant of oxygen and the reaction constants for the oxidation of the model compounds indoxyl and L-ascorbic acid could be measured. The combination of a non-stationary diffusion with a second order reaction can be described by a differential equation. For comparative purposes the oxygen distribution in different depths of the gel was measured polarographically. An exact agreement between the calculated and the measured values could be found. This result was the prerequisite for the calculation of the oxygen distribution in compact foods in which polarographic measurements cannot be carried out. The reaction constant of linoleic acid in fatty foods has been determined by measuring the increase of the peroxide-value (POZ). The diffusion constant of oxygen in a compact food could be determined using the time-lag-method, which Barrer developed for plastic films. The quotient of reaction constant and diffusion constant is characteristic for the shift of the reaction front into the compact food. In most packaged oxygen-sensitive compact foods the gradient of the distribution of decomposition products is quite flat.