Pressure!

[frankie52]

Where I live cheese molds/forms with followers for pressing cheeses are not readily available so anything I want I have to order from overseas which with the cost of international shipping makes them prohibitively expensive. I am therefore going to make my own using locally available food-safe materials. It is very likely that the ones I make will not be of the same dimensions as those I can buy and which are referred to in cheese-making recipes so to put the cheese "into a 1kg mold and press with 5kgs for 30 minutes" will be meaningless. 

What I am trying to find is a table of cheese-pressing pressures for different cheeses in lbs per sq. inch or gms per sq. cm which I can then use to calculate what weight I will need using the forms/molds I have made.

Does anyone know where I might find this information?

I would be very grateful for help/guidance.

[rsterne]

If I can paraphrase the excellent advice given by mikechar here on the forum....

Press slowly at first, increasing the pressure to maintain drops of whey running out, not a stream....

Flip and rewrap about every half hour....

Keep increasing the pressure as needed to keep the whey being expelled slowly, never in a stream....

By the time 2 hours have elapsed all whey should be expelled and the rind knit.... Flip and rewrap for overnight pressing....

At this stage basically it does not matter how much pressure you use.... but here is what I use....

Cheddar and other salted, milled cheeses - 3.5 to 7 psi (the drier it is, the more pressure needed)....

Other semi-hard to hard cheeses - 2 to 3.5 psi....

Semi-soft to medium cheeses - 1 to 2 psi....

I have found that the instructions in most cheese recipes are less than helpful to just plain problematic.... Pressing too much, too early, traps whey and causes acidic centers with cracks and voids, and even a crumbly texture.... Correct initial pressing is critical.... Hope that helps....

Bob

[mikekchar]

To be fair, I'm quoting Caldwell in turn :-)  The important thing to keep in mind is that cheese drains on its own.  You don't press it to get whey out.  In fact, if you press it too hard, you close the rind and the whey can't get out.  It will get trapped in the cheese, causing the cheese to get to acidic and creating problems in aging.

Pressing is for closing the rind (which you shouldn't try to do before it has finished draining).  The problem is that cheese knits *much* more easily when it is less acidic.  The cheese gets more and more acidic over time, and so you need to *start* pressing early and aim to close it as soon as possible after it has finished draining.  It usually takes about 2 hours to drain, so your goal is to press it as little as possible, aiming for it to close at about 2 hours in.  Flipping and inspecting regularly will help it drain evenly and help you see how it's going so you can adjust the pressure.

Cheddar is special because it has already drained before you start pressing it.  It's also fairly low pH (high acidity).  This means you need to press it like crazy.

I never follow recipes for pressing weights and pressures and advise others to similarly ignore them.  They are helpful for the original maker because their setup will produce similar situations each time.  It will only be helpful to you if you are lucky.  More likely it will cause problems (because everybody's cheese and setup is slightly different).  If you pay attention to your cheese and keep your goals in mind, I practically guarantee that you won't get it wrong.  It is *much* easier than it seems.

[paulabob]

When buying forms to use as molds, keep in mind that larger surface area requires more pressure than smaller.  It can make quite a big difference.

[rsterne]

When buying forms to use as molds, keep in mind that larger surface area requires more pressure than smaller.  It can make quite a big difference.

A larger surface area mold will require more FORCE (weight) to reach the same pressure.... but pressure is independant of surface area (the area is included in the measurement in the denominator).... If you require "X" psi (pounds per square inch) and you double the area of the follower, you must also double the force (weight) applied....

Bob

[frankie52]

When buying forms to use as molds, keep in mind that larger surface area requires more pressure than smaller.  It can make quite a big difference.

But I'm not buying forms I am making them.

[paulabob]

Frankie, I meant when you buy whatever materials you are using to make the form.   I think there's plenty of straight sided harder tupperware that could work as a form.

And yes, I should have said weight and not pressure.

[frankie52]

Frankie, I meant when you buy whatever materials you are using to make the form.   I think there's plenty of straight sided harder tupperware that could work as a form.

And yes, I should have said weight and not pressure.

Ah I see, thank you.

[DeejayDebi]

I just wanted to add that when pressing hard or semi hard cheeses less pressure is required when pressing under the hot/warm whey. I used 1 gallon milk jugs balanced a board in my sink for years to press even cheddar for a perfect press. I know what the theory is in pressing weights but if you don't have the space or place hot whey and a few gallons of milk work great up to a 6 pound wheel. I only say 6 pound wheel because that is the biggest I have experience with.