Pressing Cheeses - Reasons

[Moonshae]

This may be a dumb question, but I don't want to mess things up. My recipe says to press for 20 mins at 20 lb, then 20 mins at 40, then 12-16 hr at 50. I've started the 20@20, but it seems like the pressure eases up over time. Should I make sure the pressure stays at 20 or allow it to creep lighter? I'm assuming that as the whey is squeezed out of the curd, the pressure goes down. However, if I set this to press overnight at 50 lb, I won't be able to get up regularly overnight to keep increasing to 50. What's proper?

Thanks!

[linuxboy]

Start and keep at 50 (or higher). Those lb values are just arbitrary based on the idea of using a spring-type press that you keep tightening. There's no basis for it in terms of optimal press other than that it worked for one person and that person wrote the process down. Commercially, most cheese is pressed with a lot more weight (20-50x more).

[Moonshae]

Thanks, I'm following the gouda recipe from Ricki Carroll's book, so I assumed her directions were specific for a reason. Knowing that I need to keep the pressure at least that high for the length of time is what I was after, thanks again!

[linuxboy]

She likely has a reason, and it might be the same one as I posted, or it might be different, but science says that those numbers are arbitrary. I press goudas with a straight 5 PSI under whey, and then move to 5-7 PSI, and it works fine.

For your cheese, try to stay awake for the first hour, that's when you lose the most whey and when you need to tighten the spring. Then go to bed. Press under whey as the prepress to get a better knit.

The whole press lightly at first idea is used by some people under the wrong premise that pressing with too much weight results in a dry cheese. This is not correct. By the time you press, a large weight difference will result in negligible difference in the final cheese moisture. The moisture in curd (MFFB) is determined by the milk PF, rennet amount, set time, agitation, and cook schedule. By the time you press, the curds need to knit together, and a 100 lb difference will be negligible in terms of the final paste. Basically, it's too late. So you can crank up the weight and go; you need the weight for the curds to have a good knit. This is for hard cheeses. Now granted, some weights are excessive. You don't need to go to 50 PSI for most cheeses (you do for milled curds).

[dthelmers]

"The whole press lightly at first idea is used by some people under the wrong premise that pressing with too much weight results in a dry cheese. "

I was told that the light initial pressing was to expel whey, and that if I pressed too hard it would trap whey in the center. Not true? Can I dispense with the initial light pressing?
Dave in CT

[Moonshae]

I've read that it's to keep the curds from squeezing up out through the gap between the follower and the mold...sounds like there are a number of different "reasons" out there, but maybe none of them are actually applicable if people aren't doing it.

[linuxboy]

I was told that the light initial pressing was to expel whey, and that if I pressed too hard it would trap whey in the center. Not true? Can I dispense with the initial light pressing?

So it's like this. When you use a set time based on flocculation, that is the foundation for the final moisture content, in combination with curd size. When you mess with the foundation (like having a 1x multiplier and 1" cubes), it messed things up. It creates moisture gradients in the curds. THAT is what causes trapped whey issues. Another thing that causes it is uneven curd size. Trapped whey results from having curd that is undercooked for the flocculation and curd size used.

Yes, absolutely, if you undercook and the situation I described happens, then having a slow knit is helpful because you have stress fractures that are like guides for the whey to escape. But, this is suboptimal. By this time, it's a sort of quickfix for a mistake made earlier. It can be helpful at home as an extra sort of insurance, sure.

Insert Quote
I've read that it's to keep the curds from squeezing up out through the gap between the follower and the mold

Yes, also possible if you're using a homemade mold or if the technology of press and mold that you're using makes it likely that curds will squeeze out.

in the end, use whatever method works for your situation. But as for the original question, there's no foundational reason for pressing lightly at first vs normally, provided that the rest of the make went well. There's all sorts of things you can do to influence knit, like prepressing, adjusting ambient temp, etc. And based on the process you use, there may be many appropriate methods and approaches.