The effect of some preservatives on natural microflora in milk samples
1995
Benda, J. (Vyzkumny Ustav pro Chov Skotu, Rapotin (Czech Republic))
A comparison of the efficiency of some preservatives used for instrumental analysis of microflora composition of milk is presented. The preservatives used in the trial involved potassium bichromate, Milkofix preparation on the basis of colloidal silver, sodium azide and Bronopol. Groups of microorganisms (mesophile microorganisms, coliform microorganisms, lactic fermentation bacteria, enterococci and staphylococci) were selected with respect to their expected occurrence with natural contamination of milk. There were highly significant differences (P=0.01 %) between the preservatives in preservation effect shown as the number of colonies of the particular groups of bacteria. The best preservation effect was determined in Bronopol for all groups of microorganisms somewhat worse preservation capacity was found out in potassium bichromate. Sodium azide and Milkofix had similar preservation characteristics; they had equivalent effects on lactic fermentation bacteria, Milkofix was more efficient in inhibition of enterococci while sodium azide was more efficient against mesophile microorganisms. The studied groups of bacteria can be divided on the basis of sensitivity to the used preservatives into organisms sensitive to preservatives including staphylococci and coliform microorganisms, and tolerant organisms that can grow even in the presence of preservatives, including enterococci, lactic fermentation bacteria and mesophile microorganisms.
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