Blue Cheese

Blue cheese is a mushroom lover’s cheese.  Over cheeses such as Stilton, Gorgonzola and Roquefort, fungus runs rampant.  This fungus that makes cheese blue sends out its mycelial roots through the flesh of the cheese and slowly digests it.  Stilton would be more like Cheddar were it not for the introduction of blue mould, which softens the cheese and spikes it with intense mushroominess.

The fungus that makes cheeses blue is known as Penicillium roqueforti.   Spores of this fungus are intentionally added to blue cheeses in their infancy.  As these cheeses age, the fungal spores germinate.  The fungus slowly spreads throughout the cheese, consuming and softening its flesh as it grows.  When the fungus reaches the surface of the cheese and finds itself in the presence of air, it realizes it has a chance to reproduce and begins to produce its spores.  What we see as fuzzy blue/green patches on blue cheese are in fact vast fields of microscopic mushrooms, emitting billions of spores.

Penicillium roqueforti is a member of the penicillium genus of fungi, known for their transformative effects on many types of food.  In short, the penicillium genus loves to decay food – its many species are found degrading various foods including fruit, vegetables, garlic, bread, meats and, most significantly, cheese!  Strangely enough, when this decaying Penicillium mould finds its way into cheese, it transform it into blue cheese.

Blue cheese would normally only turn blue upon its surface, where the Penicilium roqueforti fungus finds air.  To create blue veins throughout the cheese, cheesemakers trick the penicilium fungus into reproducing on the interior.  They do this by piercing their blue cheeses with skewers, thus introducing air into the cracks and crevices of the cheese, and thereby encouraging the fungus to sporulate where it normally wouldn’t.


Making blue cheese blue isn’t all that hard to do.  The Blue method is a slight variation of the soft-bodied curd methods of camembert, feta and washed rind cheeses.  This cheese is a four-stage process, with a total ripening time of two months or more. Two unique steps to making blue are the introduction of the appropriate mold spores, and the use of a skewer to introduce air to a cheese’s interior.  Otherwise, this type of cheese follows the same pathway as many other aged soft cheeses.

The whole process can be summarized as follows:

First: make soft bodied curds,  being sure to introduce Penicilium roqueforti mold spores into the ripening milk.  Form your curds into appropriately sized cheeses.
Second: salt and air-dry your cheese.
Third: create airways in your cheese to grow blue veins.
And fourth: age your fungus infected, skewered and salted cheeses in a cheese cave.

=====Here’s the complete recipe=======

Part One: Make soft-bodied curds.  (for more information on this part, see Soft Bodied Curds)

1. Get at least one gallon of GOOD Milk

One gallon is the minimum amount of milk I would suggest using for this recipe.   One gallon of whole milk will make three personal sized blue cheeses.  Typically I make just one blue cheese per gallon of milk – each cheese usually weighing in at a bit more than one pound – four inches round and four inches high.

Be sure your milk is at least unhomogenized.  It’s best if it’s raw.  The less processing the milk has been through, the better the milk will perform in its transformation into cheese.

2. Warm that milk to 90F

Blue cheese is typically made at a medium temperature.  This temperature will be maintained through the entire first part of the process.

3. Add your starter culture

Add the appropriate amount of starter culture. You can add a quarter cup of kefir per gallon of milk.  Or a quarter cup of active whey.   Or the right dose of freeze-dried mesophilic DVI starter culture.

4.  Add your ripening culture (penicilium roqueforti)

Cheesemakers now add their penicilium roqueforti spores.  Most contemporary cheesemakers used freeze dried fungal spores, available from most cheesemaking supply shops.  You can also use a small amount of ripe blue cheese- dissolving a teaspoon of mouldy cheese in water releases enough spores to inoculate one gallon of milk.  I use my own blue mould culture, which I keep in my cave on a piece of bread. I snap off a fingernail’s worth of dry, mouldy bread, and release the spores in water.  I then pour the water with its spores through a strainer to remove the bits of bread, directly into my gallon of milk.

5. Incubate at 90F for 1 hour

Keep the pot of milk covered with a lid and insulated with dishcloths to keep the warmth of the milk contained.

6. Add the appropriate dose of rennet

Dissolve a normal dose of rennet into a small amount of water, according to the directions of your particular rennet, and pour it directly over the warm milk. Stir the rennet into the milk slowly.

7. Incubate at 90F for 1 more hour.

Put the lid and towels back on the pot.  Warm up the milk slightly on the stove if necessary.  But do not add too much heat, which might burn the developing curd on the bottom of the pot.  And do not stir, which will impede the development of the curd.

8. Test for a clean break

Stick your finger into the curd at a 45 degree angle.  Then lift your finger straight up. The curd should split cleanly into two as your finger breaks the surface.

9.  Cut your curds

Cut the curd with a long straight knife into 1-inch cubes with three series of cuts in the pot.  First, cut slices vertically from one side of the pot to the other. Wait five minutes, then proceed with the second series of cuts, vertically at an angle perpendicular to the first set of cuts.  Wait another five minutes, and cut at the curds on the final angle, 45 degrees to the horizontal.  Cut through the pot from both sides to assure that the curds are cut throughout.

10. Stir the curds intermittently until they develop their strength.

Stir the pot slowly at first.  Pick up your pace as the curds strengthen. 30 minutes to 1 hour of intermittent stirring (a thorough stirring every five minutes is ideal) is needed to develop the strength of the curds. Be sure that the temperature of the pot stays near 90F. When the curds have the consistency of a poached egg, whey off…

11.  Whey off

Allow the curds to settle in the pot for a few minutes- the whey will rise and will be easier to pour off.  Pour off the whey and reserve for Ricotta.

12. Strain the curds by hand into the appropriate sized forms.

A 1-kg yogourt container with holes punched throughout makes an excellent sized form for 1 gallon’s worth of soft curds. You can find a large selection of European cheese forms at cheesemaking supply shops.    Strain your curds directly into your forms.  Some cheesemakers salt their curds just before forming to help the curds firm up slightly before being formed.  This early salting keeps the curds from knitting together, and results in greater cracks within the cheese that results in more significant blue veining.

13. Let the cheeses form.

Allow the filled forms to sit upon a draining table and drain for 24 hours.  Protect your cheeses from flies and other pests by covering the forms with fine cheesecloth. The curds will come together and form into cheese.  Be sure to flip your cheeses so that they are evenly shaped on both sides.

14. Flip your cheeses

At some point during the 24 hours of draining, flip your cheeses in their forms.

Part Two: Salt and air-dry your cheeses

1. Salt the cheeses

Add 1 tablespoon of fine, non-iodized sea salt to the surface of each gallons worth of cheese.  If you make three cheeses out of one gallon of milk, apply 1/3 of a tablespoon of salt to each.  Spread the salt evenly over the surface of the cheeses.

2. Air-dry the cheeses

Place the cheeses back in their forms and let them sit out on the draining table for another 24 hours. The salt will pull moisture out of the cheeses, and they will begin to weep.  Flip the cheeses at some point during the 24 hours of drying to assure that the cheeses drain well on both sides.

Part Three: Introduce airways into your cheese

Get a fine skewer – wooden or steel.  Pierce the cheeses liberally.  The more holes you make, the more air will enter your cheeses, and the bluer they will get.  Pierce the cheeses from all sides.  A one-pound cheese can be skewered over 20 times.

Part Four: Age your cheeses in a cheese cave. Tend to your cheeses as they age.

After forming, salting, drying and skewering, place your cheeses into an appropriate ageing environment.  Just like most aged cheeses, blue cheeses prefer moist and cool conditions.  Temperatures below 12degreesC and humidity above 95% are ideal conditions.

My cellar works well, temperature-wise, for most of the year.  And I can age my cheeses within during the fall, winter and spring months.  In the summer, I move my cheeses into my refrigerator.

Humidity-wise, neither my cellar, nor my refrigerator are ideal – both environments are too dry.  To increase the humidity in these spaces, I keep my cheeses within closed containers.  I will often keep my cheeses inside Tupperwear containers, lined with bamboo mats to keep cheeses breathing on all sides, and to keep them from too much exposure to plastic.

Sometimes I wrap my cheeses in cheese wrappers.  You can wrap cheeses in wrappers known as mini cheese caves that promote ideal ripening conditions within – high humidity, but also breathability.

Your cheeses will need attention as they age. I examine mine twice weekly to see how they are evolving.  I check to make sure they are not too wet (if they are, I will let them dry out for a short time out of their wrapper).  I wrap and unwrap the cheeses, which allow them to breath, and keeps the mould growing evenly.

All told, your blue cheeses will need between one and two months of ageing until they ripen. The best way to tell if a cheese is ripe is through experience. And the best way to experience is to taste…It’s best to make multiple cheeses so that you can sample one – the others should ripen similarly.

Part Six: Enjoy. With friends.

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