Invited Speaker Australian Society for Microbiology Annual Scientific Meeting 2018

Salmonellosis and eggs: closing the feedback loop from research to regulation (#109)

Thilini P Keerthiratne 1 , Kirstin Ross 1 , Howard Fallowfield 1 , Harriet Whiley 1
  1. Flinders University, Adelaide, SA, Australia

Salmonellosis is a foodborne illness of public health significance. In Australia the incidence of salmonellosis has been significantly increasing over the last decade with eggs and raw egg products identified as the main source of outbreaks. Worldwide, the primary cause of salmonellosis is Salmonella enterica serovar Enteritidis; however, in Australia it is S. enterica serovar Typhimurium. Currently, in Australia it is not possible to produce eggs guaranteed to be free for Salmonella contamination and as such, post collection control methods are essential for protecting public health. Our research focuses on investigating the science underpinning food safety regulations for handling eggs. This research includes:

- An investigation into the impact of egg storage temperature on S. Typhimurium contamination. This study found that eggs stored at 4oC had reduced S. Typhimurium penetration through the egg shell and reduced internal contamination. This evidence suggests that the Australian guidelines should include regulation to enforce refrigerated storage of eggs.

- Examination of the Australian guidelines for producing raw egg mayonnaise free from Salmonella contamination found that they may not be supported by evidence. Current guidelines state that the mayonnaise should be prepared daily in small batches and refrigerated immediately. However, this is study found that temperatures protected S. Typhimurium from low pH reducing the effectiveness of this control measure.

- Characterisation of sous-vide pasteurisation of eggs as an on-site method to provide eggs free from contamination. The optimum conditions for the control of S. Typhimurium and the influence on eggs properties, including viscosity, colour, thermal coagulation and the egg protein quality were identified. The acceptance and usability of the produced pasteurised eggs for the production of raw egg mayonnaise was also tested through a blind control study of chefs.

Future research examining current guidelines and food handling practices is needed to continue to inform improved regulations for better public health protection.