A review has looked at a number of ways to try and ensure burgers served rare are as safe as those that are thoroughly cooked.

The sale and consumption of burgers served less than thoroughly cooked (LTTC) and pink in the middle is a growing trend, prompting concerns of an increased risk of E. coli O157 infections, according to the Food Standards Agency (FSA).

The FSA believes burgers served LTTC should have the same level of protection as thorough cooking gives the consumer, which is a 6 log reduction in microbial load. However, it is unlikely this will be achieved solely at the catering level. Safe production of LTTC burgers at caterers is likely to rely on controls and interventions to reduce microbiological risks at beef processing facilities earlier in the supply chain.

Food firms serving LTTC burgers must have documented and validated evidence of procedures in the supply chain that can achieve at least a 4 log reduction before the burger is served to the consumer.

No single intervention, apart from E-beam irradiation, can realistically deliver 4 log reduction of microbiota on carcasses or beef cuts, according to the review.

Consumer protection
“The integrated and coordinated use of multiple interventions in the ground beef production chain may be able to reduce microbial loads sufficiently to offer the same level of protection to consumers from burgers, which are produced with these interventions and are served LTTC as that of thoroughly cooked burgers originating from the conventional ground beef production chain,” according to the review by Dragan Antic at the University of Liverpool.

The work covered a range of GHP-based and hazard-based interventions from cattle received in abattoir up to and including finished product packaging and storage. More than 300 articles were used for data extraction and reporting.

It looked at effectiveness of each intervention in reducing indicator bacteria such as aerobic colony counts, Enterobacteriaceae, total coliform and generic E. coli counts and foodborne pathogens, primarily E. coli O157 and other Shiga toxin producing E. coli and Salmonella.

only potable water, thermal treatment with hot water and steam pasteurization, and lactic acid beef carcass washing have been permitted for use in European abattoirs.

Stage and type of measures
Multiple use of interventions featuring knife trimming, steam vacuuming, pasteurization treatments and organic acid washes had the biggest impact on microbial reduction on beef carcasses, more than any of them applied alone.

Pre-slaughter beef interventions included good hygiene practices such as lairage cleaning, proper cattle handling to prevent hide cross-contamination, and hide cleanliness assessment.

Post-slaughter interventions included good hygiene practices during carcass fabrication to prevent and minimize carcass cross-contamination post-chill. Hot water or chemical substances have shown good reduction effects but these treatments can only be used if optimized to retain acceptable sensory quality of final products.

Modified atmosphere packaging (MAP) and vacuum packaging are useful to extend shelf life of beef trim and ground beef, but they had very limited impact on E. coli O157:H7.

Novel technologies for beef, such as electron beam, gamma and UV light irradiation, high-pressure processing, cold atmospheric plasma and bacteriophage treatments, merit further investigation but commercial uptake will depend on consumer acceptance, according to the report.