What are they?
Mites are microorganisms that are found everywhere. You are probably familiar with some common mites, such as dust mites. There are also two common groups of mites found on cheese: Tyrophagus and Acarus. These are typically soil-dwelling mites, they feed on fungi in forest soils. When they encounter a cheesemaking or maturation facility, they thrive because of the high density of their favorite food: mould. They are also commonly found in grains and other types of stored foods where mould can grow. Outside of the cheese industry, these mites are commonly known as storage mites.
What kinds of cheese do they live on?
Cheese mites are found on aged cheeses with natural rinds. British examples include clothbound cheddars or natural rinded blues such as Stilton, French examples include Comté, Tomme de Savoie, Cantal and Mimolette, and in Germany there is a famous mite-ripened cheese called Milbenkäse.
How can consumers identify cheese mites?
Individual cheese mites are microscopic, so tiny that you cannot see them with the naked eye. Wherever hard cheeses with natural or clothbound rinds are matured or sold, you will usually have at least a few identifiable examples of cheese mites. If there is a cheese with lots of cheese mites, you will see brownish/grey powdery dust on the rind of the cheese. There is usually a sprinkling around the base of the cheese on the surface it sits on too. This dust is a sign of cheese mite activity.
Do they pose a risk to consumers?
According to microbiologist Benjamin Wolfe, “there is no published evidence that consumer exposure to cheese mites can cause any harm... Most pieces of cheese that a consumer would take home from a store will have just a few cheese mites on them, if any.” Whilst they aren’t risky, they are perhaps unappetising, which is why you may not have heard of them before. British squeamishness when it comes to cheese mites is longstanding. In 1903, this film of cheese mites on Stilton was reportedly the first film ever banned in the U.K., for fear it would hurt cheese sales.
How do UK maturers feel about them?
We asked Gareth, who leads our hard cheese maturing team; “They are annoying, but manageable. I see it kind of like the war on drugs. We have an unwinnable war on our hands, but an even keel is readily achievable. If you let things slide it could get really bad, but provided you have the staff and tools, it shouldn’t be too big of an issue in a maturing room.”
How do we tackle them in Neal’s Yard Dairy?
“A few cheeses demand a targeted approach, some cheddars, Red Leicester and Mature Kirkham’s Lancashire. Brushing these cheeses on a weekly basis when we turn them covers it. We just use a white brush on the cheese and flip the boards the cheeses live on so any mites fall to the ground and can be washed away. Some of the harder cheeses we select are matured on the farm until they are almost ready to go, so we do not house huge volumes that could become unmanageable for our small team” Gareth shares.
What happens if they run riot?
“There have been two considerations” says Gareth. “Firstly, they can cause skin reactions for cheese maturers who have sensitive skin. Secondly, there's a hypothesis that buildup of mite can have a negative effect on flavour. We don't really explore this, as we tend to want to avoid them running riot long before an effect on flavour happens." As we are reminded each time we talk to our maturing team, much of the work of cheese maturing is cleaning. Just as you seek to minimise dust in your house, the cheese maturers on our team seek to minimise cheese mites.
How do cheese mites affect the maturing process?
There may, according to Gareth, be an indirect positive effect, in that because we have to monitor them, it encourages us to keep a closer relationship with the cheese. "Many of the cheddars we sell don’t require weekly turning, but we do it as part of the brushing/mite maintenance process, so we are looking closely at the cheeses each week, observing their progress."
How does the cheesemaker/make affect how much mite we see?
"To take blue cheese as an example, the make, acidity and distribution of moisture in the cheese all play a part. If the cheese is too acid, it tends to be harder and drier and thus more prone to mite. Mites are aquaphobic, so the pinkish, rosy rind of a Colston Bassett Stilton won’t appeal as much."
What do the cheesemakers themselves do to stay on top of it?
"In Europe there are big pieces of machinery on the market, mostly for the likes of Comté makers. Westcombe Dairy’s famous “Tina the Turner” cheddar robot brushes the cheese as part of her process. Others use hoovers, blast with pressurised air or use manual brushing like us. I’ve heard of cheesemakers using food grade diatomaceous earth, but there’s a question over whether that dries out the cheese rind too, which would in fact make it more susceptible to mite. Until relatively recently, when it was banned by the EU, the easiest thing for cheesemakers to use had been regular gassing of the cheese stores with methyl bromide. Now, a more hands on approach is required."
How have attitudes to mites changed over time in the UK?
“I’d say they used to be more accepted as a part of the cheese maturing process, and that people tend to be more averse to them now” asserts Gareth. There is that oft cited Daniel Defoe quote from 1724 - “We pass’d Stilton, a town famous for cheese, which is called our English Parmesan, and is brought to the table with the mites round it, so thick, that they bring a spoon with them for you to eat the mites with, as you do the cheese.” Nowadays that might be considered an extremely sarcastic restaurant review...!
How does the British aversion to mites differ from, say, Germany or France?
There are cheeses on the continent which celebrate the action of mites and how this affects the matured cheese. Milbenkäse, a German delicacy, is matured in a wooden box together with cheese mites using a process that dates to the Middle Ages. There is even a cheese mite sculpture to memorialize this cheese in the German village of Würchwitz.
Likewise, the more commonly known Mimolette has cheese mites applied to its rind as part of the maturation process, giving it its characteristic craggy rind and no doubt contributing to its dense texture.
What should our customers do at home if they encounter a “mite-y” piece of cheese?
Cheese rinds that have mite damage tend not to be especially tasty anyway, and so are generally avoided. From a flavour point of view, mite on the cheeses we sell is only really an issue if a little of the dust from the rind has migrated onto the cut surface of the cheese. This should be gently scraped off, just as you would with surface mould, as it can bring a slightly musty flavour to the cheese.