Professional paper
Determination of the freezing point in cow milk samples preserved with azidiol
Nataša Pintić-Pukec
; Croatian Agricultural Agency, Poljana Križevačka 185, Križevci, Croatia
Zdravko Barać
Ana Dakić
Danijela Stručić
Davorka Blažek
Abstract
The study involved determination of the freezing point of cow milk by a reference (thermistor cryoscopy) and an instrumental (infrared spectrometry) method. The aim of the study was to evaluate the possibility of milk freezing point determination in milk samples preserved with azidiol by using a reference and an instrumental method of analysis. Five hundred cow milk samples were analysed during three research periods. Samples were taken at milk collection points in north-western Croatia. Samples preserved with azidiol (0.3 mL azidiol/40 mL; 0.011 g sodium azide/40 mL) and without preservatives (control samples) were analysed. The freezing point of milk was determined in duplicate. Average freezing point results of azidiol preserved samples were lower compared to control samples. A statistically significant difference between the means of the results obtained for azidiol preserved and control samples was determined (P<0.05; P<0.01) in all research periods. The results revealed a significant influence of the preservative azidiol on milk freezing point determination regardless of the method of analysis applied, which could lead to wrong interpretation of the results.
Keywords
cow milk; freezing point; preservative; thermistor cryoscopy; infrared spectrometry
Hrčak ID:
75429
URI
Publication date:
27.12.2011.
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