Is there horse in my wors?

Donna Cawthorn and Louw Hoffman

Introduction

There are few things closer to the hearts of South Africans than a tender, succulent piece of meat. Whether leisurely turning a coil of boerewors on the braai or devouring a handful of biltong or droёwors during a sports game, meat consumption is deeply entrenched in our culture and heritage. Nonetheless, as the local population has increased, so too has the demand for meat, making it among the most expensive food commodities in this country. The prices of beef and mutton have escalated particularly since the year 2000 and these are now considered as luxury items in South Africa, retailing at over double the price of chicken and 1.5-fold more than pork.

Although stringent food labelling regulations are being implemented worldwide, in this time of rapid globalisation – when a single processed food may contain ingredients sourced from a dozen different nations – numerous opportunities exist for unscrupulous suppliers to fraudulently substitute constituents for financial gain. Indeed, food fraud has become big business. The UK Food Standards Agency estimates that up to 10% of commercial food products may be counterfeit, practices estimated to cost the global food industry about £25 billion (over ZAR 300 billion) per year (Shears 2010). Products such as meat and fish are especially prone to substitution due to their high market values and these infractions are often simple to implement. The flesh of many meat species differs only subtly in appearance and texture, making visual identification difficult.  Once meat is comminuted and incorporated into value-added items, however, identification based on appearance and other sensory parameters becomes virtually impossible.

Typical cases of intentional meat adulteration involve the substitution of animal proteins (normally cheaper varieties) or plant proteins (such as soya or grain derivatives) not declared as such in the ingredient list.  While the presence of undeclared species in meat may be accidental in some cases, due to ignorance or cross contamination, such occurrences are generally no less negligent. Cross contamination can arise, for instance, when improperly cleaned equipment is used to process meat from multiple species. Whether deliberate or unintentional, the ability to detect less desirable or objectionable species in meat products is important not only for economic, health and religious reasons, but also to ensure fair trade and compliance with legislation (Singh and Neelam 2011, Nakyinsige et al. 2012). Today, DNA-based methods are considered the most appropriate means for making species identifications as DNA is present and identical in all tissue types, is relatively stable at high temperatures and the diversity afforded by the genetic code allows the differentiation of closely-related species (Singh and Neelam 2011, Lockley and Bardsley 2000).

Meat Examinations

During the lead author’s PhD studies in Food Science at Stellenbosch University (2008 – 2011), disturbingly high levels of fish species mislabelling were discovered on the South African market using DNA-based techniques: 9% of fish samples collected from seafood wholesalers and 31% of those collected from retail outlets were mislabelled in terms of species, with the majority involving processed products (Cawthorn et al. 2012).  The next obvious step to take on initiating post-doctoral research in 2012 at the Department of Animal Sciences, Stellenbosch University, was to use comparable methodologies to determine whether similar problems existed in the marketing of red meat commodities in this country. This novel study involved the collection and analysis of 139 packaged meat products over a five-month period (April to August 2012) from retail outlets and butcheries throughout the Western Cape, Eastern Cape, KwaZulu-Natal and Gauteng.

The five sample categories collected included mince, burger patties, comminuted deli meats (luncheon loaves and viennas), raw sausages (boerewors, species and mixed species sausage) and dried meats (biltong and droёwors).  The species declared in each product were recorded and taken into account when interpreting the results. Protein-based ELISA methods were used to detect two undeclared plant-derived components in the samples, namely soya and gluten, both designated as common allergens that require declaration on product labels according to the South African labelling legislation (R.146/2010). DNA-based techniques were used to detect and confirm the presence of undeclared animal species (beef, water buffalo, pork, sheep, goat, horse, donkey, hare, rabbit, chicken, turkey, goose and duck) in the samples.

Taking all analysed products into account, undeclared plant and / or animal species were detected in 95 of 139 (68%) samples, the highest incidence being in sausages, followed by burger patties, deli meats, mince and then dried meats. Astonishingly, these findings come at a time when consumers are increasingly seeking information and transparency in food marketing and when the newly implemented food labelling legislation (R.146/2010) requires the declaration of all product components on labels of packaged foods.  Soya and gluten were identified as undeclared components in a large number of samples (>28%) and at fairly high levels, not only contravening R.146 regulations, but also posing considerable risk to allergic or intolerant individuals. Pork and chicken were the most commonly detected undeclared animal species in the meats – identified in 46 (37%) and 28 (23%) products, respectively – of concern from an economic perspective (both are cheaper than beef and mutton) and a religious viewpoint (Muslim and Jewish dietary laws prohibit the consumption of pork).  Somewhat less conventional species which were also discovered included goat and Asian water buffalo, which were each detected in four samples. Perhaps of greatest concern from a regulatory, health and ethical standpoint was the detection of undeclared donkey meat in one sample sold in KwaZulu-Natal as “quality sausage,” for which the only animal species declared was beef.  Since donkey is not commercially processed for human consumption in South Africa, there is a high likelihood of its intentional substitution for economic gain, coupled with uncertainty as to whether the animal in question was slaughtered, inspected and processed in a registered abattoir and posing questions on the potential risks to human health.

In a related study carried out by our group in 2012, the problem of species substitutions involving game meat served at local restaurants has been uncovered using DNA sequencing techniques. To date, a total of 33 samples have been collected from six expensive restaurants specialising in game in the upmarket areas of the Western Cape. Of these, 20 (61%) samples have been genetically identified as different species to those declared on the menus.  Transgressions have included samples marketed as “springbok carpaccio’ and “kudu carpaccio” substituted with ostrich and beef respectively, three samples of “warthog” substituted with domestic pig, three samples of “springbok” substituted with fallow deer, “kudu” steaks substituted with black wildebeest, blesbok and springbok, “impala” steaks substituted with warthog, “gemsbok” steaks substituted with waterbuck, springbok and kudu, as well as “ostrich” on a mixed game platter substituted with beef.

Conclusions

Overall, these findings raise significant concern on the functioning of the meat supply chain in South Africa.  While local regulations are in place to protect consumers from being sold falsely-described or inferior foodstuffs, without appropriate and continuous enforcement, it cannot be generally accepted that correctly described meat products will remain available on the market.  These results should thus compel not only meat purveyors to take more responsibility in ensuring proper traceability of their products and to comply with the relevant regulations, but also for government authorities to identify targets for improving meat labelling practices, to address the adequacy of authentication monitoring and to contemplate whether the penalties issued for non-compliance are sufficient to deter fraudulent practices.  Against this backdrop, DNA-based methods have been shown to be powerful, highly applicable tools for species identification in meat products, the use of which by industry and regulators could provide superior levels of precision to authentication monitoring and law enforcement. 

References

Cawthorn, DM, Steinman, HA and Witthuhn, RC (2012) DNA barcoding reveals a high incidence of fish species misrepresentation and substitution on the South African market. Food Res. Internat. 46: 30–40.

Lockley, AK and Bardsley, RG (2000) DNA-based methods for food authentication. Trends Food Sci. Technol. 11: 67–77.

Nakyinsige, K, Che Man, YB and Sazili, AQ (2012) Halal authenticity issues in meat and meat products. Meat Sci. 9: 207–214.

Shears, P (2010) Food fraud – a current issue but an old problem. Brit. Food J. 112: 198–213.

Singh, VP and Neelam, S (2011) Meat species specifications to ensure the quality of meat: a review. Internat. J. Meat Sci. 1: 15–26.

Peer-reviewed link

Cawthorn, DM, Steinman, HA and Hoffman, LC (2013) A high incidence of species substitution and mislabelling detected in meat products sold in South Africa. Food Control 32(2): 440-449.

http://www.sciencedirect.com/science/article/pii/S0956713513000236

*This article first appeared in FST (South African Food Science and Technology) magazine and is reprinted by kind permission. See www.safst.co.za

Dr Donna Cawthorn is a Post-Doctoral Research Fellow at the Animal Sciences Department, Stellenbosch University, Matieland 7600, South Africa who specialises in DNA-based identification of animal species, and a part-time consultant for Food & Allergy Consulting & Testing Services (FACTS) in Milnerton, Cape Town, SA; Professor Louw Hoffman is a meat scientist in the Department of Animal Sciences, Stellenbosch University, who is recognised as a world leader on factors affecting the meat quality of exotic meat such as game and ostrich