Results revealed that 95 of 139 (68%) samples contained species which were not declared on the product labelling, with the incidence being highest in sausages, burger patties and deli meats.
The findings hold considerable financial, religious, ethical and public health ramifications, said the researchers.
They suggested the results could be due to deliberate substitution with cheaper species being harder to detect in processed meat by visual observation.
However, accidental cross contamination during processing due to improper handling and use of shared equipment could also be a factor, Cawthorn et al said.
Europe has recently been rocked after horse meat was found in frozen beef burgers and other products, from firms including Nestlé, Ikea and Findus.
Raw sausage test
The study of South Africa detailed that in raw sausages, donkey DNA was found in one sample labelled as “Quality beef sausage” after using the PCR detection method.
“Since donkey is not a species commercially processed for human consumption in South Africa, there is a high probability that this indicates a further case of intentional substitution for economic gain.
“The possibility thus exists that the meat may have been processed under non-sanitary conditions, which could pose potential risks to human health.”
Undeclared goat was found in three sausage samples and water buffalo was identified in a sample sold in a supermarket.
Regarding the goat findings, the researchers said: “This species comprises a very small percentage of the commercial livestock sector and its availability in supermarkets and butcheries is very limited in comparison to other domestic meat species.
“…such findings can likely be attributed to intentional addition of this species, rather than cross contamination.”
Asian water buffalo appeared to have been completely substituted for what was supposed to be “beef mince” in two products, according to the researchers.
Goat was also detected in one sample labeled as “mutton mince”, they added.
Pork was the most common undeclared species found in the mince products, with 15 of 40 (38%) samples testing positive for this species with the majority of the products labelled as “beef mince”.
However, horse, rabbit, hare, goose, mallard duck and muscovy duck were not identified in any of the samples evaluated.
A total of 139 processed meat products (minced meats, burger patties, deli meats, sausages and dried meats) were collected from retail outlets and butcheries in South Africa over a five month period.
Items collected included minced meats (41), burger patties (20), deli meats (33), raw sausages (35) and dried meats (10).
Samples were screened for the presence of 14 animal species, including water buffalo, sheep, horse, rabbit, donkey and goat using a qualitative LCD array kit.
Results were confirmed by species-specific polymerase chain reaction (PCR) and in some cases DNA sequencing.
The enzyme-linked immunosorbent assay (ELISA) was employed for the detection of undeclared plant proteins (soya and gluten) in the samples.
“In spite of the growing demands for transparency in the food industry, the results emerging from this study have revealed that the mislabelling of processed meats is a reality in South Africa…” concluded the researchers.
Journal: Food Control, volume 32, issue 2, August 2013, pages 440-449
Online ahead of print, doi: 10.1016/j.foodcont.2013.01.008
“A high incidence of species substitution and mislabelling detected in meat products sold in South Africa”
Authors: Donna-Mareè Cawthorn, Harris A. Steinman, Louwrens C. Hoffman