The team from Chapman University published two separate studies on meat mislabelling, one for game meat and the other on ground meat, in consumer commercial products.
One found 10 out of 54 commercial game meat products tested were mislabelled.
The other revealed 10 out of 48 ground meat products tested were mislabelled and two products from online distributors contained horse meat – which is illegal to sell on the US commercial market.
Mislabelling appeared to be due to intentional mixing of lower-cost meat species into higher cost products or unintentional mixing due to cross-contamination during processing.
Ground meat study
For the ground meat products study 48 samples were purchased from five online and four retail sources, including supermarkets and specialty meat retailers, representing 15 different meat types.
DNA was extracted from each sample in duplicate and tested using DNA barcoding of the cytochrome c oxidase I (COI) gene.
The resulting sequences were identified at the species level using the Barcode of Life Database (BOLD).
Any samples that failed DNA barcoding went through repeat extraction and sequencing, and due to the possibility of a species mixture, they were tested with real-time polymerase chain reaction (PCR) targeting beef, chicken, lamb, turkey, pork and horse.
Meat samples from online specialty distributors had a higher rate of being mislabelled (35%) compared to those from a local butcher (18%) and bought at local supermarkets (5.8%).
Among the 39 samples found to contain just one species, sequence queries against BOLD allowed for positive identification at the species level for 38 of them.
All of these samples were found to be correctly labelled except one product purchased from an online specialty meat distributor which was labelled as yak burgers but identified as cattle.
“This distributor sells ground beef products for US $22.00/kg compared to their yak burgers which retail for US $43.98/kg. This is a case where economic gain is a likely cause of mislabelling, as substituting the lower-cost beef for yak can result in a two-fold profit for the company,” said the researchers.
Nine samples were found to contain multiple species with real time PCR.
Results for two turkey samples from the local butcher revealed lamb, chicken, and beef, while the sample from the online specialty meat distributor was positive for lamb and chicken.
“The undeclared species that were detected in the turkey samples with real-time PCR were either more expensive than turkey (beef and lamb) or considered about the same relative cost (chicken) as turkey, indicating that economic fraud was not the cause of mislabelling,” said the researchers.
“The presence of multiple species commonly found in ground meats, and the fact that these retailers sell the species detected suggests the possibility of cross-contamination at the processing facility.”
Game meat study
For the game meat study 54 samples of whole-cut game meats were collected from four online distributors in the US and 22 different types of fame meat were found.
Ten were determined to be potentially mislabelled - six were associated with economic incentives based on differences in retail prices, while four were priced lower than the list price for the identified species.
These were sequenced across a 658 base-pair region of the cytochrome c oxidase subunit I (COI) gene.
The resulting DNA sequences were identified based on top species matches in BOLD and GenBank.
Results showed that 18.5% were potentially mislabelled and 9.3% of samples legally contained a near-threatened or vulnerable species and were correctly labelled.
Two products labelled as bison and one as yak were identified as domestic cattle.
A product labelled as black bear was identified as American beaver and one as pheasant was found to be helmeted guineafowl.
“The other products appear to have been misbranded for other reasons, such as inadequate traceability systems and/or mishandling by the distributor or supplier. It is also possible that products may appear to be mislabelled due to cross-species hybridization or inconsistencies with classification, said the researchers.
Study 1 on ground meat: Source: Food Control Volume 59, January 2016, Pages 158–163
Online ahead of print, DOI: 10.1016/j.foodcont.2015.05.020
“Identification of species in ground meat products sold on the U.S. commercial market using DNA-based methods”
Authors: Dawn E. Kane, Rosalee S. Hellberg
Study 2 on game meat: Source: Food Control Volume 59, January 2016, Pages 386–392
Online ahead of print, DOI: 10.1016/j.foodcont.2015.05.043
“DNA barcoding reveals mislabeling of game meat species on the US commercial market”
Authors: Charles A. Quinto, Rebecca Tinoco, Rosalee S. Hellberg