In the Journals

Frequently undercooked chicken liver propagates Campylobacter infection in UK

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June 15, 2016

Residents and chefs in the United Kingdom appear to prefer chicken livers cooked rare, resulting in a substantial portion of commercially served livers never achieving the internal temperature necessary to prevent Campylobacter gastrointestinal infections, according to recently published data.

“In the United Kingdom, increasing numbers of outbreaks are attributed to undercooked chicken livers despite the fact that the U.K. Food Standards Agency (FSA) has provided guidelines for safely cooking them,” Anna K. Jones, PhD, MSc, environmental research officer at Bangor University, Wales, and colleagues wrote. “These increased infections seem to have coincided with a trend among leading chefs to advocate minimal cooking of chicken livers, despite the need to maintain liver cores at 70°C for 2 to 3 minutes to ensure they are Campylobacter free.”

Jones and colleagues recruited 1,030 U.K. residents and 143 chefs to participate in a survey on cooking and serving preferences. They presented participants with photographs of seven batches of chicken liver cooked at various levels and asked whether each was prepared to each respondent’s preference or would meet FSA safe cooking guidelines. In addition, the researchers modeled Campylobacter survival by inoculating 60 livers with C. jejuni, cooking each at various temperatures and recording the presence or absence of bacteria.

The model predicted Campylobacter survival rates of less than 0.001% when livers were cooked in accordance to FSA guidelines, although livers cooked at core temperatures of 66°C and 52°C demonstrated 48% and 98% survival rates, respectively.

Forty-three percent of the surveyed public reported eating chicken livers and were included in the analysis. Of these, 30% identified livers with predicted Campylobacter survival rates of 48% to 98% as safe to eat, while only 9.8% of the surveyed chefs indicated similarly. Although chefs were generally better than the public at identifying livers meeting FSA recommendations, they falsely perceived customers as favoring livers served more pink than what would meet the guidelines (P = .008).

Based on these observations, the researchers hypothesized that 18.9% to 51.7% of livers being served in commercial U.K. establishments may never reach a core temperature of 70°C and have Campylobacter survival rates ranging from 48% to 98%.

“We contend that the explanation for the discrepancy between cooking practices and recommended guidelines is a cultural one, resulting in preferences for taste and texture overriding the desire to avoid foodborne illness,” they wrote. “Our interdisciplinary approach, using relatively large samples of chefs and members of the general public, provides a unique insight into the possible public health implications of a divergence between preferences and safe cooking.” – by Dave Muoio

Disclosure: The researchers report no relevant financial disclosures.

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