More on the subject of Penicillium roqueforti, aka Blue Mould

You know you’re a fermentation fetishist when you’re  nurturing a half dozen different mother cultures on your counter.  Amongst my counter-cultures (how I refer to these mother cultures on my counter) I count:  kefir, sourdough, kombucha, brevibacterium linens, and the one I’m addressing here today:  a blueish green slice of mouldy bread I use to make my blue cheese!


Blue cheese mould is the ultimate counter-culture.  It’s easy to grow on a piece of bread, and, once you-ve grown it and dried it out, the dry mould spores will last for years without any care.  Whenever you need a little bit of mould culture to make blue cheese, simply break off a very small piece of the  mouldy bread, dissolve it in some cold water, then pour it over your ripening milk.  The mould spores will come to life in the warm milk, and as the cheese ages, the blue mould will spread out its mycelial roots and transform your cheese into a blue dream


Now why would anyone keep a piece of mouldy bread Blue Breadabound on their  counter to inoculate their blue cheeses?  Tradition!  Once upon a time, cheesemakers would introduce mouldy bread into their blue cheeses to encourage them to bloom. Today, most cheesemakers inoculate their cheeses with the help of Danisco, the Danish biotech bought out by Dupont in 2011 that manufactures the vast majority of cheesemaking cultures worldwide.  You may say that Danisco is manufacturing not just cheesemaking cultures, but cheesemaking culture.

Danisco came to me one day and said:  why not buy our culture!  It’s a whole lot easier to maintain that your traditional cheesemaking culture, and really, not all that expensive.  Thank you, Danisco,I declined, but I’d rather not participate in your homogenization of the world’s culture.  And I need not pay a dime for my mould!

So I keep a mouldy piece of bread around for making cheese.  It’s easy to use, and much less expensive than a package of freeze-dried blue mould spores that were grown in a laboratory on a piece of bread just like mine. =======================================

Now I imagine at this point you’re shocked that I would use any old mouldy piece of bread to make my blue cheeses.  This is the point when I tell you that I’m not using any old mouldy piece of bread:  I’m carefully cultivating this mould culture on a carefully chosen slice of sourdough bread.

Commercial-yeasted-bread, when forgotten about in a bag in the back of the cupboard, will grow a forest of different species of moulds.  Introduce these moulds into a cheese, and you will contaminate it, possibly even poison it.  Sourdough, on the other hand, is resistant to many species of mould: its sour nature restricts the growth of most moulds.  But one species of mould tends to grow rather well on sourdough bread:  Penicilium roqueforti – blue cheese mould.

Penicilium roqueforti is a wild mould.  It is known for its transformative effects on cheese, but it also infects many other protein rich substrates and decomposes them.  Bread is another protein rich substrate, and blue mould will infect it, decompose it, and reproduce itself upon it, sending off billions of spores into the air as the mould ripens.

These mould spores move about in air currents all around us, and land on everything.  When a spore finds itself on another piece of bread or some other suitable substrate, the process repeats itself.  If these mould spores find themselves on a piece of cheese, we’re in for a treat!

As penicilium roqueforti mould decomposes cheese, its enzymes soften the cheese’s flesh.  The fungus also produces mycotoxins (fungal toxins) that give blue cheese its extraordinary taste, and sometimes make your mouth numb! Though blue cheese doesn’t produce the hallucinogenic effects of other well-known fungi, it is believed to have a powerful effect on our dreams.    This creamy, tongue numbing, dream-inducing cheese is such a delight, especially when you consider its humble, bready origins.

== Technique: ===========================

So here’s the technique for making your own culture of blue bread.

First: Get some sourdough bread

Either buy a loaf at a bakery, or bake some yourself.  I’d offer you a recipe but this is a cheesemaking blog.  Partisanship aside though, baking bread is a good exercise for making cheese.  And the two are very compatible.  As bread is baking in an oven, the top of the oven is the perfect place to ripen milk.

Second:  Infect it with some blue cheese mould

Borrow the blue cheese culture from some ripened blue cheese.  Smear a tiny bit onto a small patch on a slice of the sourdough bread.  There’s no need to spread the culture all over the bread:  the mold will grow there on its own!

Now one does not even need to intentionally introduce the mold spores onto the bread.  The mould spores will likely have already found their way onto your slice when you sliced it!  Penicillium roquefortii fungus is commonly found in our homes. It is a very opportunistic fungus that will find its way onto your food without any of your assistance…

Third: Incubate the blue bread

Place the blue infected bread in the perfect container for growing mould: Tupperwear.  Leave the container out on the counter for one week, and watch as the blue mould envelopes the bread.  The mould will start out as a small whitish patch.  This patch will spread over the bread, and as the mould growth ages, it will turn greenish blue.The greenish blue hue is a visible sign of the ripening of the mold spores upon the basidia (the microscopic mushrooms) of the blue mould culture.

Fourth: Dry the blue bread

Once the mould has completely enveloped the slice of bread, dry it out.  Open up the tupperwear, and leave it out on the counter undisturbed for another week.  The bread will dry out completely.  Put the lid back on the Tupperwear, the mouldy bread will be perfectly preserved within for years to come.

Instructions for use: dissolve in water, and pour over ripening milk.

To use this blue mould to start a blue cheese, all you have to do is transfer some spores from the bread to the milk destined to become the cheese.  To do this, I recommend breaking off a very small piece of the dry bread and dissolving it in a teaspoonful of cold water.  Sieve out the dry bread and pour the spore-rich water over the warm milk at the same time as you would add the cheesemaking starter culture to the milk.  The mould will have no noticeable effect on the cheese until it begins to grow on its surface in small white patches that ripen to a bluish green…Delicious.