Author Topic: PSI per style  (Read 16715 times)

Baby Chee

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PSI per style
« on: October 26, 2009, 06:04:32 PM »
I've been wandering around looking for a chart or some information of PSI per cheese styles.

Now that I have a huge press that can get me 11+ psi, I am curious about what the proper PSI is for traditional cheddar, gouda, jack, havarti, etc.  All the darn instructions you find on the net are just arbitrary weight: 50 lbs.  What does 50lbs. mean?  Ricki Carroll uses a 7.5" mold with 50 lbs., but that's around 1.3 psi. Not much!

So, here is a thread to have everyone jot down the PSI for different styles, unless someone made a good chart of PSIs for styles.
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Saior Con Queso and others have been saying trad. cheddar is up to or over 25 psi.  But, what is a reasonable psi for cheddar, and how does the higher psi effect the final taste and texture?  Anyone have experience in super pressing home cheddar?

wharris

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Re: PSI per style
« Reply #1 on: October 26, 2009, 06:53:53 PM »
I pressed a 6 gallon (8in mould) of cheddar under 19(ish) PSI

I will say that I brok my follower, and the cheese doing that.  I pushed the center in and bent it. There was a fracture in the cheese. 
i would not use more than 10psi going forward for that amount of cheese.

My next 25 gallon batch, will get about 10psi.

FarmerJd

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Re: PSI per style
« Reply #2 on: October 26, 2009, 07:27:31 PM »
http://www.foodsci.uoguelph.ca/cheese/welcom.htm

This link has pressure in kilopascals which is newtons/square meter. One Kp = .145 psi The only recipes listed where real pressure is needed are the colby and cheddar ones; both 75 kp or 10 psi (but then he says 10-20 psi).

He makes this statment:

"Pressing varies from little or none for soft cheese up to 172 kPa for firm Cheddar cheese. The warmer the curd, the less pressure required. Mechanical openings may be reduced by vacuum treatment before, during or after pressing."

Look at the inidvidual recipes to see the variations. 172 kp is 25 psi. They also vacuum them while pressing it seems which must make a difference in knitting as Wayne has commented on. I am satisfied with 15 psi on my cheddars for now. I did a colby this week and just used the same pressure. Everything else seems to need much less. The max I used on gouda was 5 or 6 I think and I will let you know how it turns out in a month. (Or sooner if I get antsy)

I may very well be ignorant of some other hard cheeses though. This is a good question.

Baby Chee

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Re: PSI per style
« Reply #3 on: October 26, 2009, 11:03:45 PM »
Hm, they also have shorter press times on that site, which means there is a palpable equation somewhere for time in the pressing equation.  Pity we don't know it.

My goudas were all under 1.1-3 psi for 12 hours, and I love them.  With a bit of smoke and color in there, they will be even better.

Offline DeejayDebi

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Re: PSI per style
« Reply #4 on: October 27, 2009, 03:01:11 AM »
okay this may sound strange but what if ....

You put your curds in the mould ... slipped it in a vacumm sealer bag, vacuumed it then put the pressure on? It'd have to be a fairly small mould but it might answer some questions.

Sailor Con Queso

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Re: PSI per style
« Reply #5 on: October 27, 2009, 03:12:44 AM »
I use rubber heating mats for starting seeds, I have thought about wrapping my hoops with one of these during pressing. This would probably keep the curds at 80F and facilitate easier melding. However, this would also accelerate bacterial growth. Don't know if this would be a good thing or not.

Offline DeejayDebi

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Re: PSI per style
« Reply #6 on: October 27, 2009, 03:21:40 AM »
Sailor do you mean during aging or just while packing the mold?

Sailor Con Queso

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Re: PSI per style
« Reply #7 on: October 27, 2009, 03:55:06 AM »
As Farmer pointed out, the U of Guelph site says "The warmer the curd, the less pressure required." So I have been thinking for a while about wrapping my hoop with the warm seed starter mat, WHILE the hoop is in the press. I think this might be especially helpful on larger batches.

FYI, I use the seed starter mat all the time to make yogurt and cream cheese. I sit a bowl of Mozzarella curds on the heating mat until the Moz reaches a pH of 5.2 and then it's ready to stretch. Even with inferior milk, you can just wait for the pH drop. Works like a charm every time.

zrim

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Re: PSI per style
« Reply #8 on: February 05, 2010, 11:54:43 PM »
Hi Everyone,

I am looking to jump into this PSI discussion.  The reason is that I made a farmhouse cheddar from Ricki Carroll's book and pressed it in a large diameter cheese mold which resulted in a thin (2lb) cheese.  Is Ricki talking PSI when she says 25 lbs or is she talking gross weight?

If she is talking PSI and I am using a 5" cheese mold, are the following calculations correct? 

Mold Area = Pi * (2.5)^2 = 19.6"^2
Desired pressure = 25 PSI
Required Weight = 19.6 * 25 = 490 lbs

First of all, is this the correct way to calculate the weight required for a given PSI and mold diameter? 


Beyond that, is 25 PSI a crazy pressure to go for?  I hope so!

Sailor Con Queso

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Re: PSI per style
« Reply #9 on: February 06, 2010, 12:23:24 AM »
Most recipes for home cheesemakers refer to weight, not PSI. 25 pounds means 25 pounds, not 25 PSI. A 25 POUND pressing on a 5" hoop is considered "moderate". I would consider this between 1.5 and 2 PSI. The problem is that you can't use the same 25 POUNDS on an 8" hoop and get the same results. That would require 75-100 POUNDS to get the same PSI.

25 PSI is definitely a crazy amount for most cheeses. However it can be appropriate for a cheddar type, but beyond the ability of most small presses. Your calculations are exactly right.

If you use the same hoop all the time, weight is fine. If you change hoops then PSI is really important to consistent results.




zrim

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Re: PSI per style
« Reply #10 on: February 06, 2010, 12:28:57 AM »
Ok, thanks for the reply.  I get it now.

I did notice that my first farmhouse cheddar (pressed in a ~10" diameter mold) had a lot of air spaces present.  I think the PSI was just too low.

Andrewqld

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Re: PSI per style
« Reply #11 on: May 14, 2010, 10:13:29 PM »
So I am setting up my air cylinder press and have a question regarding PSI.
How do you measure this, I have a regulator and co2 supply for carbonating my kegged beer but the gauge would not read as low as some of the pressures required for cheese making, ie. a 6" mold cheese recipe requiring 50lb would only need 1.77psi and even less for 25lb. The gauge on my reg goes up to 80psi so it's not possible to measure as low as .5 psi.
Can anyone tell me what the max pressure their regulator gauge is?


Cheers
Andrew

padams

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Re: PSI per style
« Reply #12 on: May 14, 2010, 10:47:24 PM »
So many of my questions regarding psi/weight were answered on another thread, but I just thought of something... If I am making a 3 gallon (were previously 2 gallon) but the hoop size is the same, does the weight remain the same? 

It seems to me that if I am making a 3 gallon colby, but the recipe weights are for a 1 gal recipe, I would need to compensate for the increased density?

wharris

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Re: PSI per style
« Reply #13 on: May 15, 2010, 01:07:46 AM »
If the hoops size (diameter) remains the same, and you wish to maintain the same PSI between the 2 and 3 gallon batches. then yes, by all means use the same weight.

OudeKaas

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Re: PSI per style
« Reply #14 on: October 24, 2010, 06:54:34 AM »
Most recipes for home cheesemakers refer to weight, not PSI. 25 pounds means 25 pounds, not 25 PSI. A 25 POUND pressing on a 5" hoop is considered "moderate". I would consider this between 1.5 and 2 PSI. The problem is that you can't use the same 25 POUNDS on an 8" hoop and get the same results. That would require 75-100 POUNDS to get the same PSI.

25 PSI is definitely a crazy amount for most cheeses. However it can be appropriate for a cheddar type, but beyond the ability of most small presses. Your calculations are exactly right.

Wow, that does seem like an awful lot of weight! Sorry if I missed this being discussed in more detail elsewhere, but what are the home cheesemakers here realistically getting to in terms of PSI or weight per mold size for their Cheddars? I am starting from the Ricki Carrol 'Traditional Cheddar' recipe that just suggests '50 lbs' as the final pressing weight for 24 hours.

I did see this from the U. of Guelph link in their traditional Cheddar recipe: "Press overnight at 75 kPa (10 - 20 lbs/in2). Start with low pressure and gradually increase to 75 kPa."  So . . .that's 10-20 PSI, right? I am using a 4.5" diameter mold, so using same calcs :

Mold Area = Pi * (2.25)^2 = 15.9 sq in.
Desired pressure = 10-20 PSI
Required Weight = 15.9*10 to 15.9* 20 = 159 - 318 lbs (!)
« Last Edit: October 24, 2010, 07:02:27 AM by Brandnetel »