Contribution a l'étude des conditions de la reactivation de la phosphatase alcaline dans les crèmes pasteurisées

Abstract - Contribution to the study of reactivation conditions of alkaline phosphatase in creams pasteurized
In samples of cream pasteurized at high temperature (80 to 95° C) for short times (15 to 30 sec), reactivation of alkaline phosphatase occurs markedly. The conditions of this reactivation were studied and discussed. Three factors are of particular importance: temperature of heating, storage conditions and acidity of cream.
Thus, appreciable differences in the intensities of reactivation have been found when pasteurization was conducted at 80° C for 30 sec. or at 90° C for 20 sec. although the inhibitory effect exerted by these two " time X temperature" combinations on cream alkaline phosphatase were almost equivalent.
The intensity of the phenomenon is equally influenced by the temperature and the duration of storage. The maximum intensity is at a temperature around 300° C. At this temperature, reactivation is already very marked after a storage time of 12 h. At lower temperature (4° or even 11° C), the phenomenon only occurred to a small extent.
Finally, cream acidity has a marked inhibitory effect. When it reaches 4 to 4,5 g lactic acid per litre, intensity of reactivation is very low or nil.
These observations have pratical and important bearings as far as conditions of industrial treatment of pasteurized cream are concerned