The company sold the raw unpasteurised drinking milk in its vending machine, home deliveries in the South Canterbury area and online.
It has suspended sales until further testing was clear of listeria.
New Zealand Food Safety had not received any reports of illness and the product had not been exported.
New Zealand Food Safety’s national food compliance services manager Jenny Bishop said she was advising customers to check the lot number and use-by date on the product and date of purchase.
“Listeriosis infection can be serious among vulnerable groups such as pregnant women and their unborn babies, newborn babies, people with weakened immune systems, and elderly people,” she said.
The incubation period for high-risk people could be up to two or three weeks before symptoms appeared, she said.
“Healthy adults are likely to experience only mild infection, causing mild diarrhoea and flu-like symptoms.
Real Milk Timaru is a registered provider of raw milk, owned by Stu and Andrea Weir, of Glenwillow farm.
The couple posted on social media that they were “very sorry” to customers who had bought milk from August 8 onwards.
The batch numbers were 210808, 210809, 210810, 210811, 210812 and 210813.
“Our regular testing has failed to meet a listeria limit on a test and we are following MPI advice to advise our customers to discard or boil this milk. We have also suspended all milk sales effective immediately until we gain clear testing of listeria,” they said.
“This is incredibly frustrating for us and you, our customers, especially as in all our years we have not had this issue with our beautiful milk. That being said, we have a duty to our customers and your safety is paramount.”
The couple has been selling raw milk for six years. It issued a recall notice and shut down production for a week in June after listeria was found in three lots of its milk.
Real Milk Timaru is the district’s only raw milk producer and delivers about 90 litres of raw milk four days a week and sells between 120 and 150 litres a day from the on-site vending machine from its raw milk.
