Purification procedures meaningfully influence DNA quantification in milk

The isolation of highly purified DNA from milk has been one of the essential steps in an authentication process by PCR-based method. We considered the possibility that DNA quality could vary depending on the method of DNA purification used, and that these differences could substantively impact the subsequent PCR assay. In this study, we aimed to evaluate the effects of purification procedures on the DNA in milk. For this purpose, the DNA samples from milk were purified using organic solvent and two silica-based column methods, and the DNA quality was evaluated by amplifying long target sequences (> 900bp) from mitochondrial and nuclear genes, as well as by monitoring total DNA integrity, yield, purity and ratio of mitochondrial DNA (mtDNA) to nuclear DNA (nDNA). Results showed that the integrity of total DNA, mtDNA and nDNA was consistent, while the DNA yield, purity and mtDNA: nDNA ratio estimates were not uniform. The organic purification procedure produced the highest DNA yield (97 ng/mL), purity (1.58) and mtDNA: nDNA ratio (36). We concluded that purification method can profoundly influence DNA quantification in milk and organic purification can offer a potentially effective way of isolation high-quality DNA from milk.