John Bassett, a food safety consultant, microbiologist and risk assessment specialist, raised his concerns about Lm in ice cream at last month’s Institute of Food Science & Technology’s spring food safety conference.
“This is a worrying issue worrying issue of importance for European consumers and manufacturers,” Bassett remarked. “I’d be willing to bet listeria is not an uncommon finding in ice cream – if looked for.”
John O’Brien, head of food safety and quality at Nestlé’s research centre, expressed “astonishment” that the incidents of Lm in ice cream could have been around for three to five years. O’Brien called for more studies to evaluate the extent of the risk.
At the same event, the FSA’s chief scientific advisor Guy Poppy concurred that the potential risk of Lm in ice cream to vulnerable people should be examined.
The latest US recalls follow other major ice cream recalls in the US for Lm in December 2014, which according to food safety blogger Doug Powell, a former professor of food safety in Canada, suggested ice cream should now be added to the list of foods associated with Lm.
Survey for Lm in ice cream
Bassett told www.foodmanufacture.co.uk a survey for Lm in ice cream should be carried out, as well as an assessment of the risk it posed to vulnerable people, such as elderly patients in hospitals and care homes. “I think they [the FSA] should try to understand what the risks are,” he added.
Bassett, who formerly worked for Unilever and was until March 2014 a member of the Food Standards Agency’s (FSA’s) Advisory Committee on the Microbiological Safety of Food (ACMSF), expressed concern that because Lm does not grow in frozen conditions, risk managers had not considered it a risk to health in such foods.
However, he revealed that the US Food and Drug Administration had announced that the levels of Lm involved in the recent outbreak traced to frozen ice cream products made by US firm Blue Bell Creameries of Brenham in Texas, were between 1 and 10 colony forming units per gram (1–10cfu/g).
This is much lower that the limit of 100cfu/g legally permitted over the shelf-life of ready to eat (RTE) foods sold in the UK, which ice cream is classed as for microbiological purposes. Other RTE foods which are susceptible to Lm growth include soft mould-ripened cheeses, pâtés, smoked fish, cooked slice meat and sandwiches.
“While our belief about the likely dose causing illness being above 100cfu/g and lack of growth in ice cream temperatures has kept us complacent, the US outbreak is showing that 1–10cfu/g is infecting vulnerable consumers,” added Bassett.
In 2013, concerned about the risks Lm posed to vulnerable individuals, such as the elderly, pregnant women and those who were immuno-suppressed, the ACMSF considered proposing the introduction of stricter controls on Lmin RTE foods for vulnerable people. Changes proposed ranged from the complete absence of Lm, or a new low numerical value of less than 20cfu/g or less than 10cfu/g.
No guarantee of absence of Lm
At the time, director and secretary general of the Chilled Food Association Kaarin Goodburn said it was not technically possible to guarantee consistently achieving absence of Lm without applying post-pack processing. “The standard Lm methods used by industry have a limit of quantification of 20cfu/g,” said Goodburn.
Last week (April 29) Jeni’s Splendid Ice Creams in the US was reported to have destroyed 265t of ice cream and issued a product recall after listeria was found in its production facility. These recalls follow similar major ice cream recalls in the US for Lm in December 2014. Since these cases are unrelated, they suggest the problem with Lm in frozen foods is more prevalent than experts previously thought.
The British Frozen Food Federation’s technical manager Su Dakin said: “The application of hazard analysis critical control point [methodologies] and high standards of good manufacturing practices in processing, hygiene, raw material selection and environmental control will ensure that the hazards [from Lm] are controlled.
“Ice cream and dairy ice cream in the UK is produced to some of the most stringent standards in the world and is subject to high levels of routine microbiological testing by both manufacturers and brand owners.”