Fast electrophoretic detection method of adulteration of caprine milk by bovine milk

Polyacrylamide gel electrophoresis (PAGE) in presence of urea (urea-PAGE) or sodium dodecyl sulfate (SDS-PAGE) was evaluated to detect the presence of cow milk added to goat milk. A method was optimized to prepare sodium caseinate from milk in few minutes. After that, the sodium caseinate was analyzed by PAGE. The urea-PAGE was the most appropriated method to identify adulteration as caprine and bovine a alpha(s1)-caseins displayed different migration rates. When cow milk was added to goat milk at different proportions, the presence of bovine a s1-casein was detected in the mixture by urea-PAGE for a minimal proportion of 2.5% of cow milk added to goat milk. The good sensitivity, the repeatability and the short time for execution indicate that the described method will be able to be routinely applied for the quality control of goat milk in dairy industry.