Listeria can pose special challenges for artisan cheesemakers. Many make their cheese right on the farm, where the bad bacteria are right outside the cheese room door. And small producers often lack the safety training and resources available at bigger companies.
For example, Sharon McCool got a shock last year as she prepared to begin selling the first batch of cheese she had made from milk produced at her family’s organic dairy, Rosecrest Farm, in Chehalis, Washington. State inspectors told her the Swiss cheese she had laboured over for months was contaminated with listeria.
Tests showed that the bacteria was contained in a mixture of wine, water and salt, called a smear, that McCool had been brushing on her cheese each day as it aged. Without knowing it, she was dosing the cheese with listeria.
McCool threw out 408 kilograms of cheese, changed some of her practices, got rid of the smear and started over.
McCool and her husband, Gary, have for years operated a dairy, where sanitation is paramount, so she thought she was well versed in food safety. But she now sees that she had overlooked some obvious pitfalls.
Before, McCool said, she had been so proud of her new business that she had often showed visitors around, possibly introducing listeria through their shoes or clothing.
Now, visitors are kept out. “Pretty much everything is really a whole lot stricter,” McCool said.
McCool’s story is a cautionary tale for cheese makers who are coming under scrutiny from regulators over food safety practices.
The number of small-scale, artisan cheese makers has boomed in recent years but little or no formal training is required. Safety rules and enforcement also vary.
One of the nation’s most acclaimed artisan cheese makers, Estrella Family Creamery, in Montesano, Washington, not far from McCool’s farm, was shut down in October over listeria worries after the U.S. Food and Drug Administration went to court over the matter. The bacteria was found in the company’s cheese and in its cheese making and aging rooms.
Federal regulations set a zero tolerance for listeria, and public health officials say that once the bacteria gets in a food product, it can grow to hazardous levels. In many cases, listeria causes flu like symptoms and nausea, but it can be more hazardous for the very young and the very old. Pregnant women who become infected can have miscarriages or stillbirths. Yet there is debate over the level of the health threat at small-scale producers.
No reported illnesses have been tied to the Estrella cheese, or to the cheese of another company, Morningland Dairy in Missouri, that recalled nearly 31,300 kilograms of Cheddar and Colby in August.
A small number of illnesses from listeria were linked earlier this year to soft, Hispanic-style cheeses made by two Washington state artisan producers, Queseria Bendita and Del Bueno, according to the FDA.
And at least 37 people in five states were sickened by another bacteria, E. coli, after eating gouda made by a California artisan producer, Bravo Farms.
Soft cheeses – including brie, mozzarella and queso fresco – are more likely to become contaminated with listeria because they have a relatively high moisture content and low acidity, creating a more hospitable environment for the bacteria. In addition, listeria grows well at low temperatures, so even it can thrive even in a refrigerator.
Listeria is a common bacterium that can be found in abundance on farms, where it lives in the soil, plant matter, water and manure. That means that cheese makers who work on farms, as many artisan producers do, have to be extremely cautious.
“If you have a farmstead operation, because you’re close to animals and green plant materials that can be sources, you’ve kind of got to operate a facility assuming it will be contaminated with listeria,” said Catherine W. Donnelly, co-director of the Vermont Institute for Artisan Cheese at the University of Vermont. “That means that every day, you’re going to be cleaning and sanitizing.”
But she said there was little money to train cheese makers on food safety.
The FDA began a program in April to test makers of soft cheese for listeria. Inspectors have visited 102 facilities, both large and small cheese makers.
The testing was done on buildings and equipment, not cheese, and in many cases, the level of contamination found was low.
The agency said it had found listeria in the facilities of 24 cheese makers. More than half of those were small, artisan-scale operations, including the Estrella Creamery. But the list also included big cheese factories, like one operated by Foremost Farms USA in Wisconsin, a dairy cooperative that sells cheese to food manufacturers and the restaurant industry and is one of the country’s largest cheese makers. Foremost said the FDA tested 103 locations in its plant and found three that harboured the bacteria. The company said it cleaned the contaminated areas.
“Foremost Farms’ dairy products go through extensive and rigorous safety and quality protocols before they are sent to market,” the company said in a written statement.
In at least one case, the FDA testing appears to have resulted in a recall. In July, Azteca Linda Corp. in Brooklyn, New York, recalled several Hispanic cheeses because of contamination in its plant.
Many in the artisan cheese industry fear the federal government is taking aim at the use of unpasteurized, or raw, milk in cheese making. Cheese makers believe that raw milk makes tastier cheese. But because the milk is not pasteurized to kill bacteria, federal rules require that cheese made from it be aged at least 60 days, a period during which unwanted bacteria is believed to be eliminated.
The FDA said it is inspecting both raw-milk and pasteurized cheese facilities for listeria, and recalls this year have been for both types of cheeses.
The agency also said it was reviewing the aging rules in light of evidence that the 60-day period might not be effective.