Quality of UHT goat's milk in Poland evaluated by real-time PCR

Abstract

The real-time polymerase chain reaction has been applied for the specific detection and quantification of goat's milk adulteration with cows’ milk. Beside cow-specific primers a primer pair targeting conserved regions in goats and cow's mitochondrial genomes was used to normalize the total quantity of DNA. The method has been shown to be highly specific, as the cow 300-bp amplicon was observed only in the presence of cow's milk and in mixtures of cow and goat milk-derived DNA. The usefulness of the primers used for normalization was confirmed with a dilution series of goat's milk containing cow's milk, showing that the results were not influenced by dilution of the DNA template. The standard curve with an R 2 value of better than 0.99 allows the quantification of cow milk addition in the range of 0.5–100%. The study presents also the high influence of heat treatment and somatic cell count on cow's milk quantification. The method was applied to assess the quality of UHT goat's milk in the years 2005 and 2009. Significant improvement in goat's milk quality was observed, what may be related to the tightening of quality control measurements introduced in Polish dairies in recent years.