Johannesburg - Popular supermarkets including Pick n Pay, Shoprite, Fruit and Veg City, Woolworths and Spar have been identified as stocking incorrectly labelled meat products, City Press reported on Sunday.
The newspaper reported that the retailers had largely suggested that the findings could be blamed on cross-contamination, where one type of meat was transferred to another on chopping boards, saws, hands and utensils.
Shoprite CEO Whitey Basson told the newspaper there was not "intentional adulteration to mislead consumers".
A University of Stellenbosch study found that nearly 60% of 139 products tested contained ingredients which were not listed on their labels, including donkey, water buffalo, goat and pork.
Of 32 Shoprite and Checkers products tested, 20 were wrongly labelled.
Basson said some of the findings did not make sense.
"No butcher in his right mind would intentionally add a small percentage of lamb, which costs more per kilogramme, to a pure beef sausage, which is cheaper."
PicknPay food director Peter Arnold said the quantities of undeclared animal products found in the Stellenbosch study were "minute".
He said there was an international threshold that meat could contain one percent of an undeclared product to allow for cross-contamination.
Spar group merchandise executive Mike Prentice said labelling needed to be "tightened up" and the industry as a whole needed to "jack itself up".
Louw Hoffman, the scientist behind the study, said the study had proved that the mislabelling of processed meats was "commonplace in South Africa.
"(The mislabelling) not only violates food-labelling regulations, but poses economic, religious, ethical and health impacts," he told The City Press.
The study examined meat products sourced from shops across Gauteng, the Western Cape, the Eastern Cape and KwaZulu-Natal.
Trade and Industry department spokesman Sidwell Medupe said an investigation into meat labelling was underway.