Author Topic: Measuring acidity. WITHOUT using pH  (Read 2692 times)

Online Alpkäserei

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Measuring acidity. WITHOUT using pH
« on: October 27, 2012, 01:11:09 PM »
There is an oft-repeated misconception that we have no way of judging the acidity or workings of the culture without using some means of measuring the acidity.

This of course, is a myth.

Traditional cheesemakers have made the world's finest cheeses for hundreds of years without ever once measuring the pH. While the technology has been around for centuries, it still has not yet found its way into many old world cheeses.

Throughout the process of making cheese, there are a wide number of subtle indicators that tell us how the cheese is acidifying. There are certain things that happen in the cheese that an experienced observer can use to time important parts of the cheesemaking process. A little bit of the technical side of cheesemaking can be put away in exchange for a lot of art.

The number one most important measure we have of the acidity of the cheese is the character if the whey. I was taught by a fine old Swiss Cheesemaker that you proceed to cut the curd not when the whey has reached a certain pH, but once it has become 'schon gälb' (pretty yellow). In other words, I was taught to watch the whey until it took on a precise nature of color and clarity. Then it was time for the next step. I am doubtful that he had any knowledge that it was really the acidity that we were looking out for.

If you observe the whey during the process of the make, you will notice changes occurring throughout the process. When you first cut the curd (VERY slowly, mind you) then it should be a milky white, almost like skim milk, maybe with a slight yellowish tint (if it is right away yellow, then your are too acidic). Here is where the speed of cutting is important. If you stir too fast, you disturb the whey and mess up the acidification.

When making Alpkäse, the curd is first cut to great big coarse pieces and then stirred for about ten minutes. In this time period, the whey changes color. Once it is 'Schon Gälb' then it is time to cut it to final size. Same thing when brewing the curd, once it has deepened to the proper shade of green we know the cheese is at the right stage in its development to start cooking the curd.

What is occurring here is simple, the whey when we first cut it has a lot of proteins and sugars suspended in it, but not very much acid. As the process continues, the acid reacts with the solids still in the whey to turn it first yellow and eventually to a pale green. This is caused both by acid developing in the whey itself and by acid being dispelled from the curd. This is why we don't ever work too fast, if you stir the curd too roughly, you cause it to loose too much acid which makes it difficult to judge the whey. The acid is produced by the culture, and is a direct indicator of how the culture is developing.

Now all of this comes with experience. You don't know when to move on if you don't know just what color it is you are aiming for in the whey. The differences are pretty small, and inexperience will cause you to most likely overshoot -going for too much yellow or green which means too much acidity.

This is where pH comes in handy for the hobbyist cheesemaker. You don't need the experience to judge the whey, all you need is a simple test.

I think most of us here understand the importance of acidity. We can give a recipe telling you precise times to proceed to the next step, but what is important is that we proceed to the next step when the culture is ready for it.

And what about adding the rennet? how do we know if the culture is working, and we can proceed with this steP? After all, we don't have any whey at this step to judge, do we?

Actually, we do.

Before adding the rennet, our culture is happily working away to produce yogurt. It is already producing acid, causing the cheese to coagulate very slowly. What we have, then, are small pockets of liquid separating from the milk. When we see little tiny specks of green liquid on the surface of our cheese, we know the culture is working and we can go ahead and add the rennet.
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Offline Banjoza

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Re: Measuring acidity. WITHOUT using pH
« Reply #1 on: December 15, 2012, 09:19:55 AM »
This is a fairly old post from you, Alpkäserei and I don't know why I only just found it now as it is a subject that I am interested in and has caused me MUCH vexation right from the start of my interest in cheesemaking.

Thank you for this very interesting and informative post. It is most helpful and reassuring for me too!  (I STILL can't afford a ph meter!) I made a successful Mozzarella this week by accident but I don't know what the acidity was at each stage, however your description of the colour changes in the whey do match what I was seeing in this make.  Now to duplicate that success! I will read your post again and follow the described indicators.

Offline tnbquilt

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Re: Measuring acidity. WITHOUT using pH
« Reply #2 on: December 15, 2012, 11:22:51 AM »
Thanks for that explanation. I have a ph meter but don't use it much. I have tried to incorporate using it but I got the expected ph levels wrong and over cooked my cheese trying to reach the wrong ph level, so I went back to using the time in the recipe instead.
Tammy

Offline Banjoza

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Re: Measuring acidity. WITHOUT using pH
« Reply #3 on: December 15, 2012, 01:24:54 PM »
Oh, Tammy it sounds like your ph meter may be in need of calibration. I have heard that they are sensitive and sometimes erratic instruments and need to be kept in some kind of fluid and calibrated carefully fairly regularly.

From all I have read, and the advice I have had from the experts on this site it sounds like knowing the precise ph level helps in duplicating the cheeses so that you can get the exact same result each time.  On one level it is great to have something different and unique with each make, on the other you need consistency if you want to sell the cheeses (as I do).

It's all great fun though!

Offline Tomer1

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Re: Measuring acidity. WITHOUT using pH
« Reply #4 on: December 15, 2012, 06:43:55 PM »
Also conditions such as room temp which are fairly controled in a commerical settings may change at home and effect acidification in chesses which acidify during pressing.  this is where relaying on time based recipes can cause you to under acidify or over acidify and where a pH meter can proove itself very handy.
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Offline MrsKK

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Re: Measuring acidity. WITHOUT using pH
« Reply #5 on: December 16, 2012, 04:35:14 AM »
...or experience and careful observation can bring optimal results.  Cheese has been made for hundreds of years before pH meters were invented, with consistent results.

Not everyone has to be tied down to technology!

Offline Banjoza

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Re: Measuring acidity. WITHOUT using pH
« Reply #6 on: December 17, 2012, 12:49:56 AM »
That's true Karen, and quite reassuring too, :) I have found that as time goes by I get more adept at recognising when things are going right and what needs to be done at that stage  ... but technology is lovely!  I absolutely ADORE gadgets.  Father Christmas simply must bring me a ph meter this Christmas.

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Re: Measuring acidity. WITHOUT using pH
« Reply #7 on: December 17, 2012, 08:54:54 AM »
I used Alpkäserei directions on my last 3 cheeses comparing that to the timing for each recipe, I noticed all points he is talking about are spot on ^-^
during each make it seemed to be easier to spot the next step, this can be nothing but a help in future makes :)
excellent information Alpkäserei :) 
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Offline MrsKK

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Re: Measuring acidity. WITHOUT using pH
« Reply #8 on: December 17, 2012, 10:36:06 AM »
I've been happy with the way my cheeses turn out, but have never done so scientific an observation as Alpkseri gives.  I'll have to print this out and watch for all the signs before I make cheese again.

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Re: Measuring acidity. WITHOUT using pH
« Reply #9 on: December 17, 2012, 12:02:24 PM »
Thank you for this instruction, Alpkäserei.  With all the emphasis on pH meters, I've often asked myself how cheeses have been made for so long without them.  This also answered some other questions I've had, such as why some recipes start out with large curds and then cut smaller over time.

Very, very helpful.
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Offline linuxboy

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Re: Measuring acidity. WITHOUT using pH
« Reply #10 on: December 17, 2012, 12:41:35 PM »
I was curious about your description of whey color changes so I tried it side by side with a pH meter and watched the whey. Now, I may not have understood your points, and there is a small chance the pH meter was off, but from what you describe as the beginning point to the end, there was a .01 change in acidity. So I am not sure what to make of the method. I'm sure it's useful, but I am not sure it's useful in understanding acidity behavior. Have you ever done a side by side to compare with meter readings?

Quote
What we have, then, are small pockets of liquid separating from the milk. When we see little tiny specks of green liquid on the surface of our cheese, we know the culture is working and we can go ahead and add the rennet.
I also don't understand this. It's theoretically impossible at that high pH >6.5 for any gellation to occur with acid alone. Not without some other factor such as high-temp denaturation and/or solids manipulation.
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Re: Measuring acidity. WITHOUT using pH
« Reply #11 on: December 17, 2012, 10:27:29 PM »
Alpkäserei,
How long approximately do you allow the milk to culture prior to adding rennet and approximately what temperature is the milk at this time?
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Offline Banjoza

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Re: Measuring acidity. WITHOUT using pH
« Reply #12 on: December 18, 2012, 01:20:38 PM »
It's theoretically impossible at that high pH >6.5 for any gellation to occur with acid alone. Not without some other factor such as high-temp denaturation and/or solids manipulation.

Linuxboy, I've seen this happen often here in South Africa with raw milk that hasn't been chilled. It goes solid on it's own (and not horrid tasting) In fact it is called MAAS here and it's very popular.

Offline bbracken677

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Re: Measuring acidity. WITHOUT using pH
« Reply #13 on: December 18, 2012, 01:44:24 PM »
It's theoretically impossible at that high pH >6.5 for any gellation to occur with acid alone. Not without some other factor such as high-temp denaturation and/or solids manipulation.

Linuxboy, I've seen this happen often here in South Africa with raw milk that hasn't been chilled. It goes solid on it's own (and not horrid tasting) In fact it is called MAAS here and it's very popular.

What was the pH when it coagulates?  I believe LB isnt saying that milk will not coagulate, but rather will not at such a high pH.

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Re: Measuring acidity. WITHOUT using pH
« Reply #14 on: December 18, 2012, 02:38:32 PM »
It's theoretically impossible at that high pH >6.5 for any gellation to occur with acid alone. Not without some other factor such as high-temp denaturation and/or solids manipulation.
Linuxboy, I've seen this happen often here in South Africa with raw milk that hasn't been chilled. It goes solid on it's own (and not horrid tasting) In fact it is called MAAS here and it's very popular.

Banjoza - that is happening because the native bacteria in the raw milk are multiplying and creating acid. The acid is what "curdles" the milk and makes cheese - MAAS in your case. LB is correct. You have to have the acid for the milk to "gel".
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