Author Topic: Acidification of milk  (Read 339 times)

Offline Choubix

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Acidification of milk
« on: September 04, 2017, 01:40:38 AM »
Hi,

I was wondering if anyone here knew if meso and thermo cultures where working at different speed when it comes to acidifying the milk.

Like : it takes x hours to drop the ph by 0.1 at temp y using meso (same with thermo)

Also: milk starts to curdle at what ph?

Thank you!

Offline Rain Frances

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Re: Acidification of milk
« Reply #1 on: September 04, 2017, 06:41:49 PM »
I don't have that answer but I'd also like to know!

Offline Sailor Con Queso

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Re: Acidification of milk
« Reply #2 on: September 05, 2017, 10:10:19 AM »
EVERY different species variety acidifies at different rates. So a L. lactis from one manufacturer will acidify differently than the same organism from a different manufacturer.
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Offline awakephd

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Re: Acidification of milk
« Reply #3 on: September 06, 2017, 10:29:37 AM »
Agree with Sailor - it is not just meso vs. thermo, or even one species of meso vs. another; varieties of the same species can be quite different. A good example is the primary thermophilic species Streptococcus thermophilae (ST); Danisco sells this as TA06x and as TA05x - both are ST, but the latter variety acidifies much more slowly than the former.
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Online Scarlettbri12

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Re: Acidification of milk
« Reply #4 on: September 06, 2017, 03:27:06 PM »
Is there a benefit of using one compared to the other? Or in other words: when would I want to use a slow acidifier vs a fast acidifier of the same culture?

Offline awakephd

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Re: Acidification of milk
« Reply #5 on: September 07, 2017, 09:25:51 AM »
I'll take a start at answering this from my home/hobby perspective; hopefully Sailor or others will chime back in from the professional perspective.

For me the key issue is to have all of the necessary parts of the process come together at the right place at the right time. For example, there will generally be an optimal pH at which you want to drain the whey from the curds - not always the same for every cheese; the pH at draining affects the amount of calcium in the curds, and this in turn affects the structure and texture of the cheese. However, there is also an optimal dryness of the curds, achieved by stirring and heating. So if your culture is acidifying too quickly, you may drop past the target pH before the curds are ready (or, if you drain at the right pH, the curds may still be too moist / undercooked). Conversely, if your culture is acidifying too slowly, you may wind up either over-drying the curds or draining when the pH is too high. Likewise when pressing a cheese that is salted after pressing, you need to stop pressing and start salting at the right pH; if you leave it in the press too long and the pH goes too low, you will get a much more crumbly texture than you were looking for. But you need enough time in the press to work your way up from light weight to final weight; if you press too hard too quickly, you will likely close up the rind before all the whey has drained.

Note that, in my experience - which is not anywhere close to expertise, but consists of making about 100 aged cheeses - even when I use the same cultures in the same amounts at the same temperatures, I can get different results in the rate of acidification. (And when I say "the same cultures," I  don't just mean the same variety; I mean the same package!) I believe that the key difference may be the milk at different times - all I have to work with is store-bought, pasteurized, homogenized, "standardized" milk - but still, cows produce different milk at different times in the season. My suspicion is that different batches of milk have different buffering capacity. In any case, the bottom line is that, even though there is a science to cheese making, it remains an art - even when you know the action of the culture(s) you are using, any batch of cheese needs dynamic adjustment along the way to try to get the variables to line up at the right time. (Caldwell's book, Mastering Artisan Cheese Making, is helpful in pointing out ways to do this.) If the on-the-fly adjustments are not sufficient, then you may need to find a slower or faster acidifier to use with a particular type of cheese.

Again, let me emphasize that I am responding out of my limited experience as a home/hobby cheese maker. I suspect that someone like Sailor can point to additional factors that may lead to choosing faster or slower acidifiers - for example, I think I remember seeing here on the forum that you get more subtle depth of flavor with slower acidification, but I don't know this from my own experience. Meanwhile, as a home/hobby maker, a factor that comes into play is how long the make is going to take, so that I can get to bed at a decent hour. :)
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Offline Dorchestercheese

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Re: Acidification of milk
« Reply #6 on: September 18, 2017, 07:38:33 AM »
This must be how a conductor feel with a full orchestra...you can't have the string section come in too early...

This pH thing befuddles me too..

this weekend I was ticking through a cheese make and everything was going well except at the end of the curd cook the pH had not dropped to where Caldwell recommended..now what?  I let it sit in the pot under the whey for 20 minutes more and it had dropped 0.01 more over that time..of course i didn't want to let it sit in the hot whey for too long...what to do? So i started pressing it.  It pressed fine...

I've decided I can't control everything and call it artisan cheese since each batch will be hand crafted and slightly different

Online Gregore

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Re: Acidification of milk
« Reply #7 on: September 18, 2017, 09:40:52 AM »
Yes a slower acid drop will give more flavor ....... but that is ( almost) meaningless in anything other than lactic acid set cheese  or unless you are creating your own cheese .

(The time curve can be played with by some one who makes the same cheese all the time to squeeze out a little extra flavor )

All other cheeses need to have an acid  time curve that matches the cheese style you are attempting to make .

And yes awakephd is correct
milk changes through out the year from diet , but store bought milk can also change from one week to the next if the bottler uses different ratios of milk from different farms .