South African innovation in pasteurisation of shell eggs reduces risk of infection by Salmonella enteritidis and potentially Avian influenza
A research and development (R&D) consortium under the leadership of the CSIR announced today that it has successfully developed a new pasteurisation system that greatly reduces the risk of Salmonella enteritidis infections acquired from eggs. This has led to the first sales of pasteurised, whole shell eggs in South Africa. Preliminary laboratory data indicate that the pasteurisation system may also be effective against the virus that causes Avian influenza.
Salmonella enteritidis is a disease-causing micro-organism carried by infected chickens. The yolk and albumen of eggs can be infected by pathogenic micro-organisms. This means that uncooked and semi-cooked eggs and products containing raw eggs - such as many types of desserts, tiramisu, mayonnaise and salad dressings - can contain the pathogen that leads to salmonella poisoning.
With increased restrictions on chronic feed antibiotics administered to chickens, the incidence of salmonella and other pathogens is rising and numerous countries have had to take measures in the recent past to contain salmonella outbreaks. The World Health Organisation (WHO) cites infected eggs as contributing up to 40% of reported food poisoning cases in Europe.
CSIR Executive Director: Biosciences, Dr Gatsha Mazithulela, says an increasing number of food safety problems and rising consumer concerns have led to an intensified research focus on food safety issues. He says while healthy individuals will recover from salmonella poisoning (although they may become extremely ill), the consequences of infection could be more serious in immune-compromised individuals. South Africa, with its worrying HIV infection figures, is at risk of increased salmonella-related mortalities.
With the financial support of South Africa's Innovation Fund, a research consortium was formed, pooling the skills of food scientists and microbiologists at the CSIR, sensory evaluation experts at the University of Pretoria, design engineering expertise from Delphius Technologies and commercial experts at Eggbert Eggs, the country's second largest egg producer.
Explaining the new pasteurisation system, Nell Wiid, Managing Director of Eggbert Eggs, says eggs have to be kept at exactly the right temperature during the process to destroy the micro-organism, without significant changes in the eggs' composition (cooking it!), taste or functionality. The heat in the system is generated by a combination of microwave and hot-air technology, using a specially designed oven cavity and phased process, which had been developed by Delphius Technologies, specialists in the development of industrial microwave ovens.
"The most difficult task of the project was optimisation of the heating curve and hot spot identification. Eggs vary in shape, mass, position of the yolk and heating profile and the micro-organisms are sensitive to many of these variables," says Wiid.
By the time the consortium's R&D work rendered results, warnings by the World Health Organisation on Avian flu led the team to expand its initial research objectives to include testing on a low virulence strain of the Avian influenza virus. The WHO says in a summary on Food Safety Issues, dated November 2005, that "highly pathogenic viruses * spread to virtually all parts of an infected bird*" and that "* in countries with outbreaks, eggs may contain the virus both on the outside (shell) and inside."
"Preliminary results from these trials indicate that the new pasteurisation technology also destroys the Avian influenza pathogen. While all indications are that South Africa currently remains free of Avian flu, we are encouraged by these results and by the future potential of this technology as one possible preventative measure," says Mazithulela.
Mazithulela says the research consortium has agreed on a commercialisation strategy as the technology moves forward from its R&D phase, and that an equity partnership addressing black economic empowerment forms part of the strategy.
While consumers will soon be able to make the choice to buy pasteurised eggs resulting from this new technology in selected retailers - those clearly marked as "Safe Eggs" and "Pasteurised Eggs" - the consortium is in discussion with local retailers, caterers and restaurants to consider using and selling pasteurised eggs. Pasteurised eggs will cost approximately 8c per egg more than unpasteurised eggs. Huge international interest in the technology has taken Wiid to Belgium and France and he is optimistic that South Africa could benefit significantly from this innovation.
"Eggs are a great nutritional food and we want - through this innovation - to remove all barriers that may prevent consumption of shell eggs," says Wiid.