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.
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
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?
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.
How does one differentiate between roquefortii and the myriad other possibilities of similar looking mould? And do you know of any good references or links for identifying cheese moulds? I inoculated a soft cheese with roquefortii, but i fear it could be a different mould from the air. Thanks!
myohmy1Joe Donnelly says
I have a 3 week old cheese which I notice has developed brown stain like marks. It doesn’t seem to be on the surface but appears to be within the cheese itself. Any ideas what this is and if it’s worthwhile keeping?
Gavin Webber says
Hi Joe, it sounds like a red smear caused by Brevibacterium Linens. It is fine. Just wipe it with a brine solution to keep other moulds at bay if you are trying to deverlop a natural rind.
Katherine Buchanan says
Excellent question and answer. The timing is perfect as I had been drying my Jack cheese before painting the liquid wax coating and yesterday noticed a very faint pink mould. I treated it with the salt, vinegar and let it dry. Now waiting for the coating to dry before popping it in the cheese cave. Now I'll just hope for the best and keep an eye on it. I didn't want to throw it out!
What a well-timed posting! We made Caerphily two weeks ago and I've been having to wipe the mould off it almost daily. Then this morning I noticed it was getting hairy. At that point we caved in . . . and ate it! Delicious.
Good work Goldilox. I just love the moistness of this cheese. However it does seem to attract moulds from nowhere!
However as you mentioned, the taste is delicious.
I never had a serious problem with moulds but when I had a little, I cut off the offending bit of cheese and rubbed salt into the wound. Your cheese cave at such high humidity sounds like the perfect environment for moulds to grow. My cheeses are mostly in the 1 kg range and dry out too much unless waxed so when I did get mould it was under the wax. Nowadays I coat all my cheese with the brush-on liquid wax before dipping in the hot-melt cheese wax. The brush-on product contains a fungicide and since using it I have never had any more trouble with mould. I realise that if I want a 100% natural product I shouldn't use the fungicide-containing brush-on wax, but there's so much time invested in making a cheese that I hate to see it spoil. And anyway the fungicide is on the outside and doesn't get eaten.
Hi Gavin. It is a very good question Aida Send you, and you explained in the best way how to handle mold on cheese. I get the same questions from new students, so I'd love to use your explanation of my Danish blog,if it's ok with you – that I translate it to Danish and brings it to the Danish cheese fans?
That would be okay Aase. The more Danish the better!
Dear Gavin, thank you so much for clarifying everything about molds, your answer is so enlightening! I don't feel like throwIng the cheese anymore, I will just treat it like you suggested.
when I ask myself why this mold appeared in the first place, I don't really find a good answer, because when I made the cheese I carried out proper sanitization through the process, but maybe the brining was not salty enough, or maybe most probably I didn't let it dry completely before putting it in the cave, or maybe the atmosphere is so humid in the cave because it is the old type of (used to be freezer) that has tubes of gas running through its shelves, the hygrometer always reads around 95 RH, and probably my cave needed sanitization not just cleaning , as a novice I didn't know that the cave should also be sanitized….But I will immediately spray
it with vinegar.
I feel confident now, but still concerned a bit only because of my limited knowledge and experience on the subject and because I once read on a website that red bacteria could be a deadly one called serrantia marcescens, I hope this is not the case With my cheese, as that bacteria is supposed to be blood red, and the mold I am seeing is more orange and very faint, ( I will try and send a photo), my concern is that it still comes back, anyway I will treat it as you suggested and we will see, I dared and tasted the cheese and it was ok, not tasty but probably because it hasn't aged properly.
thanks again for your great and valuable advice! I sincerely appreciate it, by the way I love your new book about cheese, and would start trying the receipes soon 🙂
You are more than welcome Aida. Happy to help