A new case study in South Korea that highlights the importance of pet food authentication to protect pets and their owners has successfully proven that DNA barcoding can help detect intentional and accidental product mislabeling.
Funded by the National Research Foundation of Korea (NRF) and published in March 2023, the case study applied DNA barcoding based on Polymerase Chain Reaction (PCR), cloning and Sanger sequencing to investigate the authenticity of 10 pet food products available in South Korea. The study didn't name the products or their brands, only saying that they are a collection of both single and mixed species labels for canned meats, jerky, particle and snacks. After rigid data analyses, four products were found to be potentially mislabeled, which can impact a pet's health if the substituents are harmful and mislead buyers in the process.
Researchers said 200 sequences of the partial Cytochrome c oxidase subunit 1 (COI) gene were generated from clones of the cat and dog food samples to detect species contents. The obtained sequences were compared to available public databases to identify species present in the ingredients. The tests showed that the labeled species were consistent with species detected by COI sequences in six of the products. However, the expected species were not detected in four products, revealing possible mislabeling in these samples.
Detection of species in pet foods by DNA barcoding
To identify the species found from the pet food samples, researchers used FishBase, Encyclopedia of Life, and NCBI taxonomy. Chicken (Gallus gallus) was the most common species that appeared in seven of the 10 examined pet food samples and they were labeled as such in six of the products, except for one product that referred to it as duck. Aside from chicken, other species detected in the tested samples included sheep (Ovis aries), cow (Bos taurus), Alaska pollock (Gadus chalcogrammus), Pink salmon (Oncorhynchus gorbuscha) and Chum salmon (Oncorhynchus keta).
Six of the 10 pet food products examined in this study were labeled correctly. All species that appeared on the product label were found in their samples, and undeclared species were not found throughout the study. In contrast, two types of dog food and two kinds of cat food were considered potentially mislabeled as they claimed to contain species that were not present on the product label or did not contain species that were present on the product label.
Since its introduction in 2003, DNA barcoding has gained popularity as a powerful method for species identification. The results of the South Korea case study and in previous studies conducted in other countries suggest a relatively high rate of pet food mislabeling, which could be from intentional or unintentional substitution by manufacturers, or from contamination in production plants that use same equipment to make various products.
Aside from DNA barcoding, researchers are suggesting an expansion of sample collection together with the use of minibarcoding and macrobarcoding to further advance pet food authentication. They say the problem of product mislabeling could only get worse as pet food makers, not only in South Korea, try to diversify the ingredients they use to expand their markets.
