Efficiency of the proportion of azidiol on preservation in ewe’s milk samples for analysis

Accuracy of milk component analysis is very important to most dairy farmers and to the dairy industry. Many factors contribute to the variation of the parameters analysed for payment purposes; one of the these factors is the method used to preserve the sample of milk prior to analysis in milk-testing laboratories. The aim of this work was to test the efficiency of different proportions of azidiol on the preservation of ewe’s milk. Fresh ewe’s milk from several origins was incubated to obtain increasing bacterial contamination ranges. Control samples versus samples preserved with azidiol (Az) or with half dose of preservative (Am) were compared. Samples were stored at different temperatures for different periods of time. Both doses Az and Am were effective enough to preserve milk either at 6 ± 2 °C for three days or at room temperature for 15 h. A dose-dependent underestimation of Bactoscan counts was detected in preserved samples versus the original counts measured in control samples. Samples preserved with Am showed results more similar to Control samples and therefore appeared to reflect with more accuracy the bacteriological condition of raw milk at origin.