Author Topic: Lowering RH to preserve cheese moisture?  (Read 456 times)

Offline ArnaudForestier

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Lowering RH to preserve cheese moisture?
« on: April 07, 2014, 04:31:11 PM »
This is interesting.  My translation from a French (University Lille) paper on Beaufort, something that first struck me as very puzzling:

Quote
The choice of humidity must consider sensitivity to the Aw of the categories of microorganisms we seek to develop on the rind surface, or on the contrary, inhibit. Where a generally high relative humidity (90-95% relative humidity) for cheese to develop surface bacterial flora, a slightly lower humidity (85-90%) for those fungal flora.

For dry rind cheeses, humidity is adjusted to a lower value (80-85%) to minimize the development of contaminating surface flora. It also allows us to limit the evaporation of residual water contained in cheese especially if, as in the case of the Beaufort, the cheese is aged over a long period.

Everything made sense to me, but the last portion (emphasis mine).  I had to double check that I had it right, and I did.  Lower RH to preserve moisture?  The only thing I can come up with is that this keeps the rind dry - and thereby seals in the pate moisture better than a cheese with a high Aw at the surface, which may "leak" interior moisture to the outside.  But this goes against all received wisdom in my world, anyway - cheeses like Beaufort, getting a long aging process, must be kept at higher RH's precisely so they don't dry out inordinately. 

Anyone?
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Offline Anonymous

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Re: Lowering RH to preserve cheese moisture?
« Reply #1 on: April 07, 2014, 06:17:25 PM »
As I research here and there, I notice contradicting things too. Here's a similar one that basically throws out everything we read in cheesemaking guides:

According to Sartoni (a Wisconsin cheese producer), they air dry at a WARM temperature for one day and then chuck the wheel in a cold brine to quickly promote a rind/barrier. The curds were dry-salted prior to pressing, so the brining here is not about salting the cheese.

So I assume that the theory is to sweat it out like you would in a sauna and then abruptly seize the exterior and close of it's porous quality. 

That would be one way to preserve moisture.

That French Beaufort study sounds like another approach to a similar objective. Sorry Paul, I don't have anything to ad experience or knowledge-wise about the subject. Just wanted to share a recent head scratcher myself.

Offline ArnaudForestier

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Re: Lowering RH to preserve cheese moisture?
« Reply #2 on: April 07, 2014, 07:36:44 PM »
Huh, that's interesting, Eric.  Definitely another head scratcher. 

I don't mind scratching my head.  My only problem is, I need all the hair I've got.  ;D
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Offline jwalker

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Re: Lowering RH to preserve cheese moisture?
« Reply #3 on: April 08, 2014, 09:31:27 AM »
This is interesting.  My translation from a French (University Lille) paper on Beaufort, something that first struck me as very puzzling:

Quote
The choice of humidity must consider sensitivity to the Aw of the categories of microorganisms we seek to develop on the rind surface, or on the contrary, inhibit. Where a generally high relative humidity (90-95% relative humidity) for cheese to develop surface bacterial flora, a slightly lower humidity (85-90%) for those fungal flora.

For dry rind cheeses, humidity is adjusted to a lower value (80-85%) to minimize the development of contaminating surface flora. It also allows us to limit the evaporation of residual water contained in cheese especially if, as in the case of the Beaufort, the cheese is aged over a long period.

I guess it depends on what you read into a statement , myself , I would take that to mean basically a compromise , the author is just stating that 90-95 is good for bacterial growth , and 85-90 is good for fungi , but 80-85 is still good enough to prevent too much moisture loss while still keeping the rind fairly clean , a higher RH may be better at preserving moisture in the cheese , but would probably require more rind maintenance.

That's what I get from it , but then , I tend not to overthink things , in fact , sometimes I barely think at all. ;D ;D ;D
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Offline ArnaudForestier

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Re: Lowering RH to preserve cheese moisture?
« Reply #4 on: April 08, 2014, 10:00:59 AM »
I hear that, Jwalker but the issue is the dehydration that is intrinsic to long-aged cheeses, throws me for a loop.  Forget what loss one can expect, I think 10% rings a bell, but that's in caves at 95%+, for cheeses aged 9-12 mos.  The 85% figure seems really low, for that reason - I would have thought not only a severe loss due to dehydration, but other issues as well. 

Not so much about the flora mix, but about the physico-chemical effects of such a low RH.  The main thing that puzzled me - how does lowering the RH in the cave - as low as 80%(!) - limit evaporation?
« Last Edit: April 08, 2014, 10:13:16 AM by ArnaudForestier »
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Offline mnml

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Re: Lowering RH to preserve cheese moisture?
« Reply #5 on: April 30, 2014, 10:11:58 AM »
How would temperature come into play here? And airflow?

I am having to carry out some serious rind duties on our hard, natural-rinds, mainly for blue mold. Even a batch that was made 2-3 weeks ago had some thriving. I am certainly glad to have come by this thread in the midst of my disheartening efforts.

Particularly, I like the previously mentioned concept of flash-brining the wheels in a cold brine. In general, I would presume using a refrigerated brine would benefit a solid, reliable rind formation for preventing moisture loss, but also for protecting from mold formation. Does anyone have experience converting their process from using an un-refrigerated brine to a refrigerated, and the effects on the cheese as it ages? Maybe it establishes a humidity threshold which allows more resiliency to your cheese through various RH?
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Re: Lowering RH to preserve cheese moisture?
« Reply #6 on: April 30, 2014, 07:57:49 PM »
Remember my rind sealing in the tomme thread? And the whole shmier discussion for rind formation that Alp started? And in another thread, I remember talking about using saturated brine to create an outer shell of dessicated casein. And somewhere else, I covered the various methods of rind treatment all with the purpose of creating a "skin" (natural or synthetic).

If you create a skin, it will slow down moisture loss. Case in point, parmigiano reggiano. thick crust, aged 12+ months, but still retains quite a bit of moisture. How? Skin, plus size to help stabilize.

The lower RH helps to maintain the outer dessicated rind, which in the style of cheese you want to make has an outer layer of polysaccharide-casein stuff (from the schmier) that acts as a sort of plastic. Increase RH too much and the cheese will soften. That skin will get smaller, ironically letting more of the moisture out from the cheese.

Pretty magical actually. Crude rudimentary old-timey approaches that prove very sophisticated when we examine them.
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Offline mnml

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Re: Lowering RH to preserve cheese moisture?
« Reply #7 on: May 02, 2014, 06:20:49 AM »
We may need to review in an organized manner over pm... But this cheese is definitely not a tomme style. Our goal is to reduce the amount of 'stain' from flora growth and have a basic rind made from mainly the outermost layer of cheese, and any airborne b. linens. Think a hard, asiago-style.
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Re: Lowering RH to preserve cheese moisture?
« Reply #8 on: May 10, 2014, 11:09:43 AM »
Emmentaler AOP has 2 options for aging, one in a 'dry' environment of 70-90% RH the other in a 'wet' environment of 90%+

The difference here is rind.

Most Emmentaler has a very minimal salt rind, this is achieved by maintaining it at a lower RH -less growth is likely-
Some has a bacterial rind, achieved by aging it in a moister environment

A lot of Alpine styles, you form the rind in a very wet environment and then move them to a drier environment for their aging period. This way, you have a proper bacterial rind, but this will remain tacky if the RH is above 90%. So we need to store it closer to 80 to 85% to let the rind harden.

What you read here is true, if the rind is tacky the cheese will be able to leech out moisture. But when it is allowed to become dry, it's almost as if you have a wax coating.
But we still need high RH to form the proper rind. That is why our rind formation is done in a separate space than the aging.

What we get with Alpkäse, the rind is formed in high RH so is bacterial by nature. Then when we store it, the RH is much lower. So the result is, we will often get some wild geo and similar fungal growth later.
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