Food hygiene of mold-ripened cheeses
Although words like mold or bacteria might sound suspicious at first, not all microbes have a bad reputation. In fact, many are indispensable helpers in the food industry. Beneficial microbes shape the texture, flavor, and shelf life of products in ways that make some of our most beloved delicacies possible.
One of the most delicious examples of this is mold-ripened cheese.
Mold-ripened cheese perfectly illustrates how mold can not only be acceptable but absolutely essential in production. Carefully selected and deliberately cultivated mold strains give these cheeses their unique flavor, texture, and aroma, which are qualities that many cheese lovers find irresistible.
But while mold is a welcome ingredient in these cheeses, that doesn’t mean harmful microbes can’t also grow in them. So what separates “good” mold from “bad”? How should mold-ripened cheeses be handled and stored? And how do you know if a cheese is still safe to eat?
To find out, we asked food hygiene expert Anja Ekström and artisan cheesemonger Nelli Steer, owner of Rolling Cheese in Helsinki, to share their knowledge and insights.
Why Is the Mold in These Cheeses Safe to Eat?
Mold-ripened cheeses are generally divided into two main groups: white mold cheeses and blue mold cheeses.
Both are made using carefully selected strains of mold, usually sourced from commercial producers. These microbes and the enzymes they produce don’t just shape the texture of the cheese—they also create its distinctive taste, aroma, and appearance.
“Molds influence both the appearance and the flavor of cheese. White mold cheeses are often creamy and mushroomy, while blue mold cheeses are saltier, more intense, and complex,” Steer explains.
According to Ekström, the safety lies in the selection: “The molds used in mold-ripened cheese are developed specifically for that cheese. They are intentionally and carefully introduced, which makes the cheese safe to eat.”
For example, the best-known Finnish blue cheese, Aura, is made using Penicillium roqueforti. It is the same mold used in classics like French Roquefort and English Blue Stilton. Italian Gorgonzola, on the other hand, also employs Penicillium glaucum. These molds grow throughout the cheese, forming beautiful blue and green veins.
White mold cheeses, such as Brie and Camembert, use different strains. Their soft, velvety rinds are formed by Penicillium candidum or Penicillium camemberti. Unlike blue molds, these typically grow on the surface, giving the cheese its recognizable white coating.
Some cheeses combine both molds. A well-known example is German Cambozola, which has blue veins inside and a white mold rind on the outside.
Many famous mold-ripened cheeses also carry a Protected Designation of Origin (PDO) status granted by the EU. This ensures they retain their traditional qualities. “For instance, Gorgonzola, Roquefort, and Stilton must all be produced, processed, and matured in specific regions to carry their name,” Ekström notes.
When Has a Mold-Ripened Cheese Gone Bad?
Mold-ripened cheeses typically keep well, but their shelf life depends on whether the packaging is intact and how the cheese is stored.
Most carry a best before date rather than a use by date. This indicates the period during which the cheese will maintain its best qualities if unopened and properly stored.
“Like with other foods, if the packaging is unopened, intact, and stored under the manufacturer’s recommended conditions, at the right temperature and humidity, the cheese usually keeps at least until its best before date,” Ekström explains.
Once opened, however, the best before date no longer applies. From then on, you’ll need to assess the cheese using your senses.
Changes in color, smell, or taste are signs of spoilage. “If foreign mold contaminates the cheese, you may see fuzzy growth on the surface, or black spots on white mold cheeses,” Ekström says.
Steer adds: “Not all visible mold means spoilage. White mold cheeses often develop gray or blue tints as they mature. But unwanted mold, like black growth, along with a slimy texture or strong ammonia smell, clearly indicates spoilage.”
Taste can also give it away. “If the cheese tastes bitter or overly acidic, it’s gone bad. If it doesn’t smell or taste appealing, don’t eat it,” Steer advises.
How Should Cheese Be Stored Safely?
Cheeses are perishable foods and require refrigeration both in stores and at home. Manufacturers are responsible for defining storage conditions and shelf life.
Food safety regulations also set clear temperature requirements:
- For cheeses made from raw milk without pasteurization: max +6°C
- For cheeses made from pasteurized milk: max +8°C
“There are exceptions for some aged cheeses, which are not considered perishable in the same way. In those cases, the producer must provide certification showing that cold storage isn’t necessary,” Ekström notes.
Unopened cheeses keep well in their original packaging, provided storage instructions are followed. Once opened, conditions change: hard and processed cheeses may last a couple of weeks, but fresh cheeses should be eaten within a few days. “It’s best to enjoy opened cheese quickly to keep its texture and flavor at their best,” Steer advises.
Hygienic Handling of Mold-Ripened Cheeses
The molds used in these cheeses are only safe when intentionally added during production. “If the same molds grow unintentionally in other foods, they spoil the product. That’s why it’s important to prevent contamination during storage, sales, and use,” Ekström emphasizes.
Careful storage is essential: packaging should be tightly sealed to prevent cross-contamination. “Even mold-ripened cheeses can be contaminated by unwanted molds in the air of a fridge. Proper wrapping prevents this and also keeps moisture from building up on the surface,” she explains.
Because cheeses are high in fat, they easily absorb odors and dry out without proper protection. “Cheese paper or wax paper is ideal because it breathes. Plastic is too tight and doesn’t allow cheese to breathe at home,” Steer advises.
In stores, mold-ripened cheeses should be clearly separated from others. “Each type should ideally have its own cutting board and knife. Wooden boards should be avoided in professional use, as they’re hard to clean and dry properly. Tools should be washed regularly, and hand hygiene is crucial. Washing hands and changing gloves after handling mold cheese are good practices,” Ekström recommends.
At home, the same applies. “Use a separate cutting board and knife for mold-ripened cheeses, especially if serving several varieties. This prevents mold from spreading between products,” Ekström adds.
Since mold spores are always present in the air, they can potentially contaminate any food. “Fresh cheeses are especially vulnerable. In industry, the risk is reduced with air filtration and strict hygiene practices. Good cleaning and hygiene in storage and sales areas also reduce contamination risks,” Ekström sums up.
Intense Flavor Experiences
Mold-ripened cheeses often divide opinion, but that’s part of their charm. “They’re bold and distinctive, and not to everyone’s taste. But that’s also what makes them fascinating: when the salty strength of blue cheese or the creamy richness of white mold cheese clicks, it can become a lifelong favorite,” Steer says.
She adds that new and interesting cheeses are constantly appearing alongside traditional classics. “Right now, some of our favorites include Stichelton from the UK, a raw-milk blue cheese with roots in the original Stilton recipe, but even more nuanced. From Italy, Blu di Capra—a rare goat’s milk blue cheese—combines freshness with depth. And from France’s Champagne region, Chaource, a white mold cheese that’s velvety, slightly tangy, and creamy,” Steer describes.
A Gateway to the World of Cheese
Mold-ripened cheeses show us that not all mold is harmful, in fact, it can be a cornerstone of flavor and culinary tradition. Steer believes their strength lies in their diversity and character:
“To us, mold-ripened cheeses are a kind of gateway into the wider world of cheese, they open up a spectrum of flavors and tell the story of cheesemaking traditions.”
Safe handling and proper storage ensure consumers can enjoy these cheeses just as they’re meant to be: intense, complex, and unique. They may divide opinion, but they rarely leave anyone indifferent.
Anja Ekström is a food science professional with extensive experience in food retail and industry. She has worked for over five years as a hygiene passport examiner and trainer at Hygieniapassi.fi, and through her own company, Loxia, she supports food businesses in safety and quality issues.
Rolling Cheese is an artisan cheese shop, deli, and wine bar in Helsinki’s Töölö district. It is Finland’s only dedicated cheese shop, sourcing handmade, high-quality cheeses directly from small producers across Europe. Alongside cheese, they offer wines, beers, and gourmet foods, host tastings, and create tailored cheese selections through their shop and online store.