Significado higiénico de la presencia de estafilococos patógenos o sus toxinas en leche en polvo

Abstract

168 spray dried milk samples have been studied from Spanish dairies in order to establish the scope in the problem of food poisoning outbreaks due to staphylococcal enterotoxin of this origin.
The preformed tests to follow this line were: staphylococcal colony counts. biochemical characteristics of the isolated strains ( coagulase, fosfatase. desoxirribonuclease, manitol fermentation, lipolitic activity, potasium tellurite reduction), phage typing, detection of the types of entero­toxin, growth of the coagulase positive strains in evaporated milk and in reconstituted powdered milk.
From the results obtained it has been deduced that despite the small percentaje of enterotoxigenic strains among the studied microflora, and the low proportion in the number of staphylococci per gram, with an ave­rage of 370, it would be dangerous to maintain, at room temperature, for several hours, the reconstituted milk.
In a normal spray dried milk process, with a holding period of the concentrated milk, before drying, less than one hour, it would not be possible, whatever the temperature mighy be, to cause enterotoxin to be produced, which avoids its presence in the final product.