It IS the water, after all

[Susan38]

I've been focusing my cheese makes on cool water washed curd recipes, as I can get relatively quick feedback about the results since they are young-aged cheeses.  I've also been chasing pH's in all of the makes that I've measured, and have been trying to figure out why.

Early on I was wondering about the best water to use for these washed curd recipes, since my tap water is well water with lots of minerals, TDS's, etc.  Most advice I found was "use any water, even tap water will do" with the exception of one comment of "if you have water with bad bacteria in it, boil it first or use bottled water".

Our well water is potable, but it does have off-flavors that I don't think would be desirable in cheese.  For drinking water we run it through a counter-top filter that takes out TDS's.  That is what I have been using to wash my curds with (for you chemistry-oriented folks out there, I surmise you are now thinking uh-oh...)

In my defense, I did read a few posts about "did you measure the pH of the water?" and such but did not find any real advice about whether or not to use water with a pH lower than 7.  And I DID measure pH's of all different waters, learning that even distilled water starts out with a pH of 7 but over time can acidify quite dramatically.  For my tap water, it was coming out at 7.9, and surprisingly (to me, a non-chemistry oriented person) the same water with TDS removed was 5.0!!

Now, you would think at this point I would put 2 and 2 together and realize the water was lowering the pH in the vat as compared to using water with a higher pH.  But I was focused on the other things that the water was doing....as in, taking away the lactose to slow down the bacteria's acidification activity, and being absorbed by the curd to make a nice elastic texture.  I also did not know if the amount of water used would be enough to influence the pH in a major way.  So I continued as I was doing, and continued chasing pH's.

It wasn't till I first used Caldwell's cool-water washed curd recipe that I finally absorbed her tip about washing the curds:  "Water will raise pH slightly, so readings will be different from those for non-washed curd cheese".  Well there it was staring me in the face. If I drained the curd with the whey pH at about 6.2-6.3, and I added water at 5.0, there is no way the pH was going to rise.  And I got to confirm this in my final make with this water.

This is all quite embarrassing, actually...although as I always say "better late than never".  And, I'm documenting this experience in the hopes it will prevent someone else from going down the wrong path that I was on for a while.  The story has a happy ending, with my most recent make using Caldwell's recipe (and bottled water with a pH of 7.54).  I got to contentedly stir and process the curds while the pH slowly dropped as per recipe guidelines.  Can't wait to try it in a couple of months!

[mikekchar]

I don't have time to reply, but definitely very interesting!  AC4U!

[awakephd]

I look forward to seeing how you will handle this ... and I will be checking the pH of my filtered water as well!

[Susan38]

For now I'll be handling the situation using bottled water (although I hate to buy water!).  The Jack recipe only uses 1 gallon and the Colby about 1.5 gallons.

I'm wondering if the absence of TDS is what causes the pH drop, or is it something in the medias that the water is filtering through that does it?

Since this water discovery, and sharing it with others, it has been relayed to me that the reverse osmosis type of water filtering also acidifies the water.  I had no idea.

[mikekchar]

pH in water chemistry is a bit tricky.  Very quickly (mainly because I've forgotten it all), pH in water is mostly governed by the balance of CO2 and CO3 in the water.  Basically (pun... ha ha ha), CO3 is the carbonate ion.  It exists when you add something like chalk (CaCO3) and the water splits the Ca ion and the CO3 ion.  However CO3 reacts with water (H2O) like this: H2O + CO3 = HCO3 + OH (note all the H's, O's and C's add up in the equation).  OH is called the hydroxide ion.  The more hydroxide ions you have in solution, the more basic the solution.  The more H ions you have in water, the more acid the water.

You probably know CO2 as being carbon dioxide.  However, when dissolved in water it becomes carbonic acid (one of the reasons why fizzy drinks are acidic).  Carbonic acid has the formula H2CO3 and is formed like: H2O + CO2 = H2CO3.  Again all the H's, O's and C's add up.  It's acidic because it dissolves in water as an H ion plus a HC03 ion (which is called bicarbonate).

You will notice that there isn't much difference between the two.  In the basic reaction you end up with HC03 (bicarbonate) and OH (hydroxide), so it makes it basic.  In the acidic reaction you end up with HCO3 (bicarbonate) and H (hydrogen), so it makes it acidic.  But they are all basically made of the same stuff.  In reality, in the water you often end up shifting back and forth between carbonate (that makes things basic) and carbon dioxide (that makes things acidic) and the actual pH of the water depends on a lot of things including temperature, dissolved oxygen, particulate matter, etc, etc.

However, the biggest thing that will swing the pH one way or the other are ions like calcium (Ca), Sodium (Na), Magnesium (Mg), etc.  The more you have of those things, the more the water chemistry is going to prefer the basic reactions -- because you end up with carbonate most of the time.  In fact it will fix the pH of the water to a certain level and it won't budge until you add enough acid to push it over the edge.  This is called "buffering".  The most stuff in the water, the more it will tend to buffer at a particular pH and will be stubborn to move.  Generally speaking, that "stuff" is counted in the TDS (total dissolved solids).  The more you have, the more it will buffer the solution at a higher pH.

When you have very low levels of dissolved solids, there is nothing to buffer the pH.  Pure water will *still* be at a pH of 7, but even the tiniest bit of CO2 or other acid will cause it to nose dive and become acidic. 

Milk is basically water with stuff in suspension.  Most of the stuff we are interested in is the casein protein.  Casein protein are tiny balls of packed protein all held together with a salt called calcium phosphate.  When the milk gets more acidic, the casein balls relax and release calcium phosphate into the water.  It then dissolves.  Once it dissolves, it buffers the pH (makes it harder to become acidic). 

When you remove whey, you are also removing the calcium phosphate that's dissolved in the whey.  If you replace it with pure water, then basically you are removing the ability of the milk to buffer the acidity being produced by the bacteria.  On the other hand, you are also removing the food for the bacteria, so in the end you lowering the total amount of acid in the long run.  However, the pH can drop very quickly if you are using water like that.

You can easily add salts back in to your water if you like.  A lifetime supply of gypsum and chalk will cost you almost nothing.  Both are easily bought at brewing supply stores.

There is much more that can and should be said about water chemistry.  In fact, I doubt my explanation is actually correct.  It's been a while, so I'm sure there are many errors.  However, hopefully it is enough to give you an intuition about how it works.

[awakephd]

Thanks, Mike - very interesting. AC4U!

[Susan38]

Yes Mike--another cheese heading your way!

I had just enough memory of my required chemistry courses from long ago to follow along!  If I'm understanding correctly, it is the absence of TDSs that are the culprit, regardless of removal technique (i.e. distillation, reverse osmosis, other filtering types).

A question that pops up is what is the source of CO2 and CO3 in the water...is it coming from the air or is it in all water or ?  Just curious.

And how is it that "regular tap water" (I'm surmising this includes city chlorinated water) is OK to use for washed curd cheeses, as I think the chlorine would damage the bacteria population in the vat?

So my filtration system is of the brand called "Zero Water" and their claim to fame is removing all TDSs from the water.  They even give you a probe to test for TDSs, and once they climb you are supposed to change the filter.  I'm not sure how accurate it is, but it measures 131 for my tap water (and this tap water is first run through a house filter system so straight well water is much higher...lots of iron, manganese and who knows what else); and measures zero (hence the brand name) when it goes through the filter.  So it is very effective for what it does, but unfortunately the company does not clue you in that having "zero water" will be acidified.  (Allowing the TDS to climb to maybe raise pH is not an option as for some reason, after it hits 6 and above,the water gains a horrible unique flavor to it and there is no question it is time to change the filter).

I think other systems (like Brita) do not take all TDSs out, and maybe the pH would not zonk down so low using them? 

Seems like my options are:
1. Figuring out how to add gypsum or chalk to my filtered water
2. Research if another filtration system would better address the pH issue
3. Mixing tap and filtered water to see if there's a balance of pH without off-flavors
4. Buy bottled water

Thanks again Mike, I always enjoy reading the detailed and well written explanations of things in your posts!

[Lancer99]

As Mike mentioned, if you remove the buffering from the water, it only takes a tiny change (e.g. in the CO2) to change its pH greatly.  But that also means that it won't much change the pH of anything it's added to.  So you could probably add a gallon of nearly pure water of pH 5.0 to a few ounces of whey and it wouldn' t change the pH at all.

R/O systems only "acidify" water in the sense that they remove impurities that make tap water alkaline, like yours at pH 7.9.  Removal of the impurities brings the pH closer to neutral.  But then, because there's no buffering, R/O water absorbs CO2 from the air and the pH drops. 

pH meters struggle with nearly-pure water, so take those readings with a grain of salt (so to speak).

Edit: I looked into the Zero Water system, and it is a dual bed ion exchange system.  These work well (and indeed, can reduce the TDS to zero), but the resins need to be replaced regularly, so in the long run they are much more expensive than R/O systems, although they don't produce waste water like R/O does.

L

[Susan38]

Lancer99,

Interesting remarks, thanks for checking in on this...I was puzzling through this very topic, of what to expect when adding a 5.0 water to a, say, 6.2 whey.  If equal parts were mixed, certainly the result would NOT be an average of the two numbers (chemistry is NEVER this simple, eh?).  I actually experienced what you are saying about the 5.0 water not affecting the pH very much, during one of my makes.  When adding roughly a gallon of the water to roughly a gallon? of whey, the pH in the vat went from 6.26 only down to 6.22.

But, the recipe I'm using says the pH should rise slightly during this stage, not fall...so I'm thinking it affects the rest of the make when trying to hit a final pH of 5.5 or so (which I keep passing and end up with a lower than ideal pH and resulting sour taste).

In comparison to the above, in another make, when I used a 7.5 pH water, I went from a whey pH of 6.35 to the mixed vat pH of 6.43.  I think this result is more in line with the recipe's guidelines so I am hoping for better results!

PS--yes the ZeroWater system is "expensive" but not too much so when just used for drinking water, as we are.  When faced with the other option of drinking our "flavorful" tap water, it doesn't seem very costly at all.   

[Lancer99]

I think the two key things are (1) the closer the water is to pure, the less it takes of anything to change its pH (and for a pH meter to get a correct reading) and (2) again, it's back to the buffering, a small amount of something that changes the pH won't have much of an effect on something with a greater buffering effect.

Probably not helpful, though.  I don't have enough experience with washed curd cheeses to offer any insight or advice.

Susan, I apologize if it sounded like I was criticizing your choice of water filtration, not meant.  For many years I kept reef coral aquariums.  Tap water has so many impurities that after making up salt water, it's unhealthy for corals, so just imagine those discussions. . For me, in the long run, R/O was the better choice.

L

[Susan38]

I think any and all explanations about how pH can work is helpful to those of us trying to make good cheeses, as manipulation of pH is one of the many factors that goes into it!

Lancer99, no worries and no apologies needed...my response was kind of an in-house joke about our water quality (I'll expand on that in another post on the lounge board so I don't go too far off-topic here).  And sometimes email is not the best form of communication!  Cheers,  Susan38

[Susan38]

This is a follow-up to my original message to document how my final Jack cheese turned out, once I started washing the curd with water pH above 7.  I'm happy to report it turned out great!  It tasted like a Jack cheese and melted like a Jack cheese.  It's the first out of five to be this good.

I'm attaching a picture of both Jack #4 and Jack #5, since they were both "opened" around the same time.  Jack #4 is on the left, the whiter, moister, crumblier one.  It was made with a P&H milk, something I had never tried before.  The milk acted so different than what I was used to, that I wasn't surprised it did not turn out well.  But what I learned from it was the difference that aging makes.  When I first opened it up at 2 months, it was not edible at all.  At 3 months it was okay but had a bitter taste.  And at 4 months the flavor was great!  Not the Jack flavor I was looking for but it was definitely an edible cheese.  Now when I taste a cheese not to my liking, I will definitely throw it back into the cheese cave to see if it will improve.

Jack #5, the yellower "pretty" cheese in on the right of the photo.  This one is my best success to date.  All the pH's and times came on target and the results are spectacular! 

[MacGruff]

AC4U

Number 5 hit the jackpot!