The authors of this study (purchase required) have developed and validated a point-of-use test for bovine DNA in dairy products.
It is based on direct PCR within a closed-loop system (a single tube, using a portable PCR machine), which eliminates the need to extract DNA from samples. Visualisation is by SYBR Green I detection of PCR amplicons giving a fluorescent marker that can be read by the naked eye. This was enhanced with the use of a self-designed portable LED lightbox, which mitigated colour interference, enabling detection in coloured products such as yoghurts without any sample preparation. Analysis time was 50 minutes.
Validation studies revealed 100% specificity when tested with 13 other species, over 99% accuracy with 208 cow’s milk and dairy products in both liquid and solid forms, 1×10−5 ng limit of detection, and 100% accuracy with blind testing.
The authors then conducted a small market survey of “milk replacement” dairy products on sale in Thailand. They found that 10.7%, contained bovine DNA, an indicator of potential dilutions or substitution with cows’ milk.
Photo by Tijana Drndarski on Unsplash
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