Common chicken cooking techniques may not ensure safety, study warns

Widespread techniques for judging whether chicken is cooked or not may not ensure that pathogens are reduced to safe levels, according to Solveig Langsrud of the Norwegian Institute of Food, Fisheries and Aquaculture Research and colleagues.

Chicken can harbour the bacterial pathogens Salmonella and Campylobacter. High temperatures can kill these microbes, but enough may survive to cause illness if meat is undercooked. 

Pictures of chicken fillets at different end temperatures (50-70°C)
Credit: Langsrud et al, PLOS ONE, 2020

To help clarify consumers’ chicken cooking practices, Lansgrud and colleagues surveyed 3,969 private households across five European countries (France, Norway, Portugal, Romania, and the UK) on their personal chicken cooking practices. They also interviewed and observed chicken cooking practices in 75 additional households in the same countries.

The analysis indicated that checking the inner colour of chicken meat is a popular way to judge doneness, used by half of households. Other common methods include examining meat texture or juice colour. However, the researchers also conducted laboratory experiments to test various techniques for judging doneness, and these demonstrated that colour and texture are not reliable indicators of safety on their own: for example, the inner colour of chicken changes at a temperature too low to sufficiently inactivate pathogens.

Food safety messages often recommend use of thermometers to judge doneness, but the researchers found that the surface of chicken meat may still harbour live pathogens after the inside is cooked sufficiently. Furthermore, thermometers are not widely used; only one of the 75 observed households employed one.

According to Langsrud, these findings suggest a need for updated recommendations that guarantee safety while accounting for consumers’ habits and desire to avoid overcooked chicken. For now, the researchers recommend focusing on the colour and texture of the thickest part of the meat, as well as ensuring that all surfaces reach sufficient temperatures.

“Consumers are often advised to use a food thermometer or check that the juices run clear to make sure that the chicken is cooked safely – we were surprised to find that these recommendations are not safe, not based on scientific evidence and rarely used by consumers,” Langsrud added. “Primarily, consumers should check that all surfaces of the meat are cooked, as most bacteria are present on the surface. Secondly, they should check the core. When the core meat is fibrous and not glossy, it has reached a safe temperature.”