A novel biosensor method to detect cow DNA in milk and dairy products

Despite being the most popular, cow's milk and dairy products are one of the major allergens for infant, young children, and adults. We developed and validated a daPCR-CHA-FB assay to detect cow DNA in milk and dairy products. During optimization, we obtained a linear relationship between synthetic cow DNA and fluorescence signal (y = 0.0437x + 0.7966; r2 = 0.9814) and demonstrated that the assay could be used without any sample preparation. An accuracy of 100% was obtained with 50 vouchered cow's milk samples. No cross-reactivity was observed with nine other species. The detection limit was 1x10-4 ng of DNA. It is also highly robust, as demonstrated with almost 250 market samples (observed fraud ratio of 15.4%). The assay could be completed in less than 2 h, does not require any DNA purification and expensive equipment such as a real-time thermal cycler or a capillary electrophoresis.