J. Dairy Sci. 90:3153–3161 doi:10.3168/jds.2007-0038 © American Dairy Science Association, 2007. Evaluation of the MilkoScan FT 6000 Milk Analyzer for Determining the Freezing Point of Goat’s Milk Under Different Analytical Conditions A. Sa ´nchez,* D. Sierra,† C. Luengo,† J. C. Corrales,* C. de la Fe,* C. T. Morales,† A. Contreras,* 1 and C. Gonzalo‡ *Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de Murcia, 30071 Murcia, Spain †Laboratorio Agroalimentario y de Sanidad Animal, Consejerı ´a de Agricultura y Agua, Comunidad Auto ´noma de la Regio ´n de Murcia, El Palmar, 30120 Murcia, Spain ‡Departamento de Produccio ´n Animal, Facultad de Veterinaria, Universidad de Leo ´n, 24071 Leo ´n, Spain ABSTRACT The aim of this research was to evaluate the Milko- Scan FT 6000 (Foss Electric, Hillerød, Denmark) for determining the freezing point (FP) of goat’s milk under different analytical conditions. The FP was determined in duplicate in 1,800 milk aliquots obtained from 45 bulk tank milk samples from 10 Murciano-Granadina goat herds, using the MilkoScan method and a reference thermistor cryoscopy method (Advanced Instrument Inc., Norwood, MA). Five different preservation strate- gies—no preservative, preservation with azidiol (0.006 or 0.018 g of sodium azide/100 mL), and preservation with bronopol(0.020 or 0.040 g/100 mL)—were then used to preserve the milk. For each preservation strat- egy, 8 different amounts of water were added (0, 1, 2, 3, 4, 5, 6, or 7% total volume).The results obtained with each method under these 40 analytical conditions were examined by comparison of means,comparison of the standard deviations of repeatability (s r and its relative value s r %), and a regression analysis.Under most analytical conditions,the FP was recorded as lower by the MilkoScan method, with a mean difference of 1.5 m ° C compared with the reference method. Both methods showed similar repeatabilities (the overall s r % was 0.22% for the MilkoScan method and 0.20% for the reference method). In comparisons of the 2 methods, the highest regression coefficients were obtained with aliquots containing >3% added water. The best regres- sion coefficients (0.85 to 1.02) were obtained for milk samples preserved with bronopol at 0.020 g/100 mL. These results allow the MilkoScan method to be used with goat’s milk for screening purposes. The factors of added water,preservative,analytical method,lactose concentration, and the effect of the bulk tank milk sam- ple within each lactose group contributed significantly Received January 19, 2007. Accepted March 8, 2007. 1 Corresponding author: acontrer@um.es 3153 to the observed variation in FP. For practical purposes, either of the bronopol concentrations could be used when determining the FP of goat’s milk with the meth- ods tested. However, the increase in the concentration of sodium azide in the azidiol formula contributed to an important reduction in the FP recorded. Thus, the type and concentration of preservative should be taken into account when interpreting FP values. Key words: goat milk, freezing point, MilkoScan, milk preservative INTRODUCTION The freezing point (FP) of milk is measured to deter- mine the presence of added water in the bulk tank milk because of certain milking operations or as a sign of fraud. European law earlier established that heat- treated cow’s milk for human consumption should have an FP no higher than − 520 m ° C (Council Directive 92/ 46/ECC; European Community, 1992). However, given the variation possible, Council Regulation no. 2597 (Eu- ropean Community,1997) determined that such milk should have an FP close to the mean FP for raw milk in the collection region. Recent years have seen an in- crease in mean bulk tank cow’s milk FP values because of changes in milking and cleaning methods (Slaghuis, 2001). Official monitoring of milk for added water should therefore take into account the unavoidable ad- dition of water to each type of drinking milk, the natural variation in raw milk composition, and decisions on acceptability (based on statistical procedures; Glaeser, 2003). This is particularly important because FP is one of the factors taken into account in payment-by-quality schemes for cow’s milk (Van Crombrugge, 2003) and goat’s milk (Pirisi et al., 2007). The thermistor cryoscope method, as defined by In- ternational Dairy Federation standard 108:2002/ISO 5764 (IDF, 2002), is the reference method for the deter- mination of milk FP. This method is based on super- cooling and crystallizing the milk;the FP is reached