I received this email yesterday about unwanted moulds on cheese which I thought would interest the wider curd nerd community.

Here is the email from Aida.

Dear Gavin,

I need your advice asap! I just made Havarti cheese 10 days ago, it is in the
cheese cave ( adapted freezer unit ), yesterday I noticed reddish, maybe pink or
orange at the top of the cheese, it is minimal and faint, the rind is a bit
oily,anyway I wiped it with vinegar salt solution, it is probably in a humid
atmosphere, maybe that’s what caused to color, but I am so concerned, because I
saw the same discoloration again today…is this dangerous and should I throw
cheese away?

Please advise asap, this problematic cheese is still in the cave
with other cheeses, will it infect other cheeses? or is this faint discoloration
normal, how do I know if it’s a mold or bacteria …dangerous or not?
thanks
Aida

Well Aida, I am sure this is a question that many new cheese makers need to ask, because we are taught from early on in life that moulds are bad things.  Sometimes that is just not correct.  Moulds are sometimes good things, especially on cheese.

The good news is that I believe that the mould you have on your Havarti is a red mould called Brevibacterium Linens which is found on Limburger, Brick, and Muenster washed rind cheeses..  However without a photograph I cannot be sure.

So before you go throwing away your cheese, lets list the types of unwanted moulds that I have experienced in my cheese making adventures;

• Black moulds that look like cats hair
• Red moulds on heavily salted cheeses
• Orange moulds
• Green/blue moulds similar to P. Roqueforti, and
• Brown moulds

I wouldn’t exactly say these are harmful in small doses, they just need to be treated correctly.

You need to ask yourself why the moulds grew in the first place.  Did you observe proper sterilisation techniques at the start of the process?  Is there cross contamination between cheese types (use a ripening box for mould ripened cheeses).  Did you use enough salt?  Was the cheese dry before aging?

Once you determine the cause, then you can take action.  For a soft cheese, you can save your cheese by carefully cutting off a slice of the offending area, rubbing salt into the wound, and hope it goes away.  For hard cheeses, brine and vinegar as you have already tried, or try cutting off the affected area, re-salt, then letting air dry again before putting back into the cheese fridge/cave.

All that said and done, a small unwanted mould will not destroy your cheese, and may even add flavour.  The only real bad one to avoid is the black moulds which should be treated immediately.  Not because it is really harmful, but because it leaves a terrible taste in the cheese.

Moulds have not killed me, and I am still alive. I have had all sorts of unique, but friendly moulds in my cheese cave at various times!  Just make sure you sanitize well, and clean out your cheese cave with a vinegar spray every few months if you want to stop the moulds from taking up house in your aging area.

Hopefully that has cleared up any misconceptions about cheese moulds.