Author Topic: sudden drop in PH  (Read 3036 times)

Offline Devon

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sudden drop in PH
« on: May 31, 2012, 07:42:09 PM »
Lately while making cheddar the PH drop is normal up to the cheddaring phase. Then the Ph drops very rapidly to the point I have to salt and press early. I have even tried raising the temp during cheddaring and stacking at a lower level for more heat transfer to expel more whey. Can anyone give any insight as to why the sudden drop in PH at this stage?
« Last Edit: June 03, 2012, 07:03:11 PM by Devon »
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Offline Sailor Con Queso

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Re: sudden drop in PH
« Reply #1 on: June 01, 2012, 08:34:10 AM »
Acidity is a logarithmic not a linear progression because bacteria theoretically double their population every 20 minutes. Every bacteria has a pH curve that predicts the rate of acid production, and for the first 2-3 hours (or more), there are not gigantic drops in pH. Depending on the cheese, the bacteria used, and the amount of starter used, that bacterial population and associated acid production "kicks in" from 3 to 5 hours into a make. You have complete control over over acidity at various steps along the way and may have to pitch, salt, and press when the cheese is ready, not because a recipe dictates a certain time.
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Offline Boofer

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Re: sudden drop in PH
« Reply #2 on: June 01, 2012, 11:33:45 AM »
Acidity is a logarithmic not a linear progression because bacteria theoretically double their population every 20 minutes. Every bacteria has a pH curve that predicts the rate of acid production, and for the first 2-3 hours (or more), there are not gigantic drops in pH. Depending on the cheese, the bacteria used, and the amount of starter used, that bacterial population and associated acid production "kicks in" from 3 to 5 hours into a make. You have complete control over over acidity at various steps along the way and may have to pitch, salt, and press when the cheese is ready, not because a recipe dictates a certain time.
This is good stuff. In the beginning, it took me a while for my mind to move from the dictates of a recipe with set times for ripening, renneting, pressing, etc., to an understanding of exactly what you're saying. I had to learn (and am still learning) what the milk was doing through the different stages. I always felt something was drastically wrong with my make if I didn't follow the recipe and do everything within the recipe's margins. The pH meter made me focus more on the actual progress within the milk. If it wasn't moving, neither was I. Why move to the next stage if the milk isn't ready? Conversely, if the milk seems like a runaway freight train, I'd better get on-board or I'll be left behind. That means my schedule is accelerated. Monitoring the pressing pH may mean stopping the press and moving to the brining phase to curb the bacteria's excitement and arrest the acidity development.

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Offline linuxboy

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Re: sudden drop in PH
« Reply #3 on: June 01, 2012, 02:33:51 PM »
That's not a sudden drop. That is a normal drop for many types and strains of bacteria.

Here's what you have to remember about milk. It buffers. It's not like even with the non-linear way that pH works, and the bacterial mix and the way bacteriology works, you can have some clearly predictable outcome. Milk is a variable medium in which to practice your art. if you are skilled, you don't need a pH meter, because you can rely on intuitive and organic observations of milk and curd behavior. For the rest of us mere mortals, pH meters/titrators are a Godsend.

If you want to drag out the curve, use less culture, or switch culture to a slower blend, or regulate temperature to better coincide with the time and moisture parameters.
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Offline NimbinValley

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Re: sudden drop in PH
« Reply #4 on: June 02, 2012, 02:23:56 AM »
I have had a similar experience to you Devon.

Now that I am more aware of renetting pH I am finding that I may have to accelerate my makes also.  I was making a Blue last week and didn't rennet until 6.45 ( which took nearly 120mins of ripening to achieve) but then the rest of the make was very quick to achieve my whey off pH of 6.2.  I actually overshot it considerable so I will use less culture next time and stir a bit faster.  I am hoping that Blues will be a bit more forgiving with the extra acid developed.

Any comments will be appreciated.

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Offline Devon

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Re: sudden drop in PH
« Reply #5 on: June 02, 2012, 05:57:30 PM »
Thanks for the input everyone. I decided to try again today making a cheddar with a few adjustments.

8 gals raw milk PH 6.72 heated to 88 degrees F
Added 1/4 teaspoon MA 011 (down from 3/4 tsp used in prior makes)
Held at 88 degrees F for 40 minutes PH 6.69
Added 1 teaspoon liquid animal single strength, floc in 15 minutes
Cut at 45 minutes into 1/2 inch cubes PH 6.57 rest for 5 minutes
Raise temp to 102 degrees F over 55 minutes PH 6.48
Held for 40 minutes PH 6.35
Drained and cheddared for 50 minutes PH 5.62
Salted (7 tablespoons) and pressed at PH 5.62 due to past sudden PH drop

It has been in the press for approximately 5 hours, is fairly dry already and the PH is at 5.30 (Updated Post) at 8 hours in and PH is 5.16, decided to remove from press to begin drying and actual PH taken from cheese is 4.94, it appears to still be dropping. (Updated Post) Final PH in the cheese this morning is 4.88 When does the PH stop dropping? This is the same problem I have been having lately where the PH drops into the range of 4.8 or lower during pressing and/or during drying.
« Last Edit: June 03, 2012, 09:01:01 AM by Devon »
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Offline linuxboy

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Re: sudden drop in PH
« Reply #6 on: June 04, 2012, 08:53:16 AM »
This looks like a decent make. Your native bacteria seem to be causing the acidification because MA11 shouldn't do that. Focus on your drain and your salt pH and the rest will take care of itself.

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Offline Devon

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Re: sudden drop in PH
« Reply #7 on: June 04, 2012, 04:15:05 PM »
So does that mean I should be draining and salting at a higher PH? If so what range should I be targeting for draining? Would it help to reduce ma11 starter from 1/4  to 1/8 teaspoon or leave out the starter completely? Every make ends up with a finial PH around 4.8 to 4.9, I want to target a finial PH of 5.2 to 5.3. I guess I am not understanding how to meet this target PH on the completed cheese, when it goes in the press, I no longer have any control over the PH drop.
« Last Edit: June 04, 2012, 04:39:14 PM by Devon »
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Offline FRANCOIS

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Re: sudden drop in PH
« Reply #8 on: June 04, 2012, 05:02:39 PM »
What Linux means is:
1.  Add more salt (slows the pH curve)
2.  Increase the pH you salt at. (shift your make up the pH curve)
3.  Monitor the pH and when it hits your target immediately put it in the chilelr to arrest the pH drop.

Any, all or one of these can get you to the final pH marker you want.

Offline Devon

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Re: sudden drop in PH
« Reply #9 on: June 04, 2012, 06:05:52 PM »

If I add anymore salt the cheese will not be eatable, the salt does not appear to be slowing down the PH drop as shown in the make during pressing. I am already salting around 5.6 to 5.8. Which part of the make do I slow down on to be able to salt earlier? The only place I see is the ripening phase at the beginning.

Even removing from the press and putting in the refrigerator after 5 hours at a PH of 5.62 as in the make before this one, the PH still dropped to 4.82 by morning.
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Offline FRANCOIS

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Re: sudden drop in PH
« Reply #10 on: June 04, 2012, 06:25:43 PM »
It sounds like indigenous culture is dictating your pH curve.  You'll have to pasteurise, or a t least thermise, if all else fails.

Offline Sailor Con Queso

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Re: sudden drop in PH
« Reply #11 on: June 04, 2012, 06:40:37 PM »
Devon,

With raw milk, you should always reduce your starter by 25% or more. As LB suggested, I would salt at 6.0.

You can also do a partial wash of the curds. Gouda washes about 1/3 of the whey. I would shoot for 10-15% whey removal. You will have to experiment with the wash temperature, but I would wash to within a few degrees less than target temp and then bring the curds up as you would normally. This will remove some of the lactose, slow the bacteria down, and help prevent your cheese from becoming too acidic.

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Offline Devon

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Re: sudden drop in PH
« Reply #12 on: June 04, 2012, 07:07:17 PM »
Sailor,

I did reduce the starter only using 1/4 teaspoon for 8 gallons, I think I will reduce it to 1/8 teaspoon. I will try your target PH of 6 then salt. I will make again this weekend. I have @ 8 – 4 lb wheels, each with the make schedule adjusted and the end result is still a ph of 4.8 to 4.9 that I guess will get trashed.

I really do not want to pasteurize unless I have to, kind of defeats the use of raw milk
« Last Edit: June 04, 2012, 07:52:12 PM by Devon »
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Offline NimbinValley

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Re: sudden drop in PH
« Reply #13 on: June 04, 2012, 07:17:13 PM »
I may be speaking out of turn here but if by 'trashed' you mean throw away then I would reconsider.  They should still be edible and may be really quite nice, not just like true cheddars.  If you were hoping to sell them then change the name  - I call mine "Oops".  The only problem is that people come back wanting to buy more 'oops'!

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Offline FRANCOIS

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Re: sudden drop in PH
« Reply #14 on: June 04, 2012, 07:31:49 PM »
Washing could have a very signifcant impact on final flavour and texture (not in a good way), so be careful.  Salting