The thing is, Peter, cheese is basically mould. Let’s take your example of blue: yes, the blue bits are mould, but so are the white ones. What we’re really talking about here is intentional mould versus mould that grows on the cheese, and for this, Dan Bliss, cheese buyer at Paxton & Whitfield, suggests thinking of your cheese as a petri dish: “It’s alive with mould, whatever style of cheese it is, and creates an environment where other moulds want to grow.” Those moulds aren’t necessarily going to do you harm, but they might affect the cheese’s taste. “If it’s surface mould, it’s fine to cut off, but if it has begun to ingress into the taste of the cheese, be it a hard or a soft cheese, it’s usually time to say goodbye.” As Max Melvin, senior cheesemonger and head of education at La Fromagerie, notes, “If something is so awful that you can’t get it near your face, you probably wouldn’t want to eat it anyway.”
Red moulds and “anything too actively yellow” are best avoided, Bliss advises, while “the greys, blues and whites” can be cut off a few millimetres from the mould’s surface. But don’t scrape it: “You can see the more active things [where it has bloomed up], but scraping may spread that across the face of the cheese. It’s better to cut it off and stop that process.” The same can be said for that fluffy mould on a cut camembert or brie.
Cheddar can form mould near the rind as well as on the surface. “You might get characteristic cracks in the cheese,” Melvin says, “which air can get into, and a blue mould similar to the one that grows in blue cheese can start forming.” For some, this is, ahem, cracking news (many of Melvin’s customers request it specifically), while others don’t like the flavour. It is, however, a different story with fresh cheese: “If you’ve got mould on that, it’s an indication not to go any further,” says Bliss, who recommends eating the likes of ricotta and mozzarella within a few days of opening.
Other cut cheeses will typically keep for about 10 days, but storage is key. “You want to create a sealed environment, but you don’t want your cheese to sweat too much,” says Bliss, who wraps hers in wax paper (or baking paper) and stores it in a plastic container in the fridge at “below 8C”. You could put a sugar cube in there, too, to suck up any excess moisture, “rather than creating condensation within the box or on the cheese”.
Having said all this, “contamination is a probability game”, Melvin says. “Cheese is generally low-risk, but obviously some are lower risk than others.” Young children, the elderly, pregnant or immunocompromised people should “generally stick to hard cheeses and be more cautious about the likes of mould and shelf-life”. As in life, though, manage your own risk: “The French have been doing so rather successfully with mouldy cheese for centuries.”