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Hello everyone. I made my first Gouda last night with 2.5 gallons of raw milk. This is my 3rd cheese overall and my first with ph issues. The ph started at 6.8, and throughout a 45 minute ripening with the cultures and another 45 minutes with rennet the ph barely dropped. I was happy with how I was able to keep the temp stable throughout, although the recipe recommended keeping the vat between 88-90 and I was consistently running a little hot, between 91-92 (not sure how problematic that is or how it would affect ph). I know for Gouda that the water should be added before the ph drops below 6.3, but I was struggling to get it close to that so I ended up washing the curds at ph 6.6. When I molded the cheese it's ph was similar.

Before making this cheese I read a lot of forum discussions about how Gouda needs to not over acidify in the Press and that it usually go faster than expected. So I have vigilantly been checking ph throughout the night, but after 10 hours the ph is only at 5.8, and at various points it has dropped and then gone back up! For example, at one point it had dropped to 5.9, and two hours later it was at 6.2.

I know that sometimes milk buffers against ph changes, but is it normal for ph to fall and rise like that? Does this cheese still have a shot at being good after aging, considering the relatively high ph that I washed the curds at and the ph roller coaster that it has been on since? Thanks in advance

pH caint rise once lowered. Is it possible the curds weren't cut evenly enough so you had moisture gradients in the cheese? That can cause pH to drop more in some spots and less in others. If that's not the case your ph meter is going haywire and needs to be cleaned (procedure on the forum here. I think Linuxboy wrote it a while back)

Both are possible...I have an extech flat electrode meter, and this is only its second use but maybe it does need to be cleaned in some way. It seemed to read the buffer solutions accurately for the most part though, so I'm not sure.

I was quite unsatisfied with the uniformity of curd size. I was trying out a new horizontal curd cutter that I made and it did not work well at all! After they were cut I tried to pare down the larger curds to size with a spatula as I stirred, with some success but it still wasn't ideal

Probably the cause then. The moisture gradient of the curd will cause un even washing in the gouda and during the pressing will cause some areas to acidify faster than others

Quote from: River Bottom Farm on August 11, 2018, 03:32:30 PM
pH caint rise once lowered.

Not that I'm doubting :-), but is that really true?  To be fair, I think your conclusions are correct (based on very little experience on my part LOL), but from a more technical point of view, I'm a bit curious about how it works.  pH is really measuring the hydrogen ions in the liquid.  As salts get introduced, the balance between H+ and OH- switches.  I used to have planted fish tanks and you can really see this as you add salts or if you add some carbonaceous material -- the pH can swing pretty quickly.

Reading Mastering Artisan Cheesemaking, I understand that casein holds a lot of calcium phosphate within the micelle and that under various conditions, it can be expelled (which is one of the reasons that the whey and the curds are different pHs).  In my own experiments, I find that I can get milk to curdle by adding acid directly, but that the final curds are much higher pH than you would expect.  One of my theories is that it takes time for the Ca3PO4 to liberate and buffer the acid.  So the milk curdles, but then the pH rebounds.

So I wonder if it's possible for it to rise and fall in stutter steps -- especially if you are having trouble measuring the curd acidity rather than the whey.

I have never seen it rise ..... except with my cheaper ph meter that was always a problem .

It is also unlikely that it was a pocket of differing whey by that much ...... it could have been a little of both things at the same time .

I found that when I make mother cultures  the night before and add them at 1.5 percent by weight I never have the slow to drop ph at first.  The good thing about it is that even with older less strong cultures you get the same start to a cheese  every time.

I realised later when I was thinking about it that if the calcium phosphate leaves the micelle and dissociates in the whey, then slowly it will migrate out of the curds with the whey.  It's unlikely to migrate *back in* (because of osmotic pressure).  This means that the pH in the curd will reduce gradually, even if the pH of the whey is buffered.  My situation is slightly different in that I'm adding acid directly while it's all still a liquid.  However, potentially, if you were to put the curd in a really cold place, I wonder if the pH could rise.  It would be interesting to try.

Just wanted to give a quick update. So ph at beginning of pressing was 6.6. After 11 hours of pressing it had gotten down to 5.6. At that point I had to get on with my life so I threw the cheese (still in its mold) into the cheese cave at 55 degrees to hopefully slow down the acidification until I got back home. 6 hours later I was able to check on it, and the ph was at 5.3, at which point I brined  it for 10 hours (the wheel is 3 pounds)

Also in the original post I failed to mention that I am using aroma B starter culture (not sure if that is relevant to this discussion)

Just noticed this article while I was searching for something else: https://www.cdr.wisc.edu/sites/default/files/pipelines/2002/pipeline_2002_vol14_04.pdf  And in trying to write this post I noticed this nice article which is much less technical: https://www.cheesescience.org/buffering.html

TL;DR: Apparently the pH *can* rise.  the buffering action in milk and in the curds (or final cheese) is different.  In milk, the buffering happens very quickly.  In the curd it can take up to a day for the buffering to happen.

Some background: Basically calcium phosphate (the salt most responsible for buffing in cheese) is available in different forms in the cheese.  Essentially (and I have to think back to my grade 7 chemistry class with all the trauma that entails) dissolved salts have 2 parts: positively charged ions and negatively charged ions.  In this case the positively charge ion is calcium and the negatively charged ion is phosphate.  Depending on the pH of the liquid and temperature and some other factors, the salt goes from being split apart and floating around in these 2 separate ions, or binding together into a salt.  Being split apart and floating around is what we call "dissolved".  When it is bound together it is not dissolved any more.  The salt can only act as a buffer when it is dissolved.  The amount that is dissolved at any time depends on the pH and temperature and other factors as I mentioned previously.

It's also important to understand that when a salt is dissolved, it does not matter where the 2 ions come from.  So it doesn't matter where you got the calcium and phosphate ions from, when they are dissolved in the liquid, it's just as if you added calcium phosphate.  And indeed, it will transition from dissolved ions to calcium phosphate salt and back over time.  As the pH goes down, more salt from the casein becomes available for buffering the pH.  As you add more acid, it uses up more of the salt as a buffer.  If you ever get interested in fish tanks you may hear terms like "carbonate level as calcium carbonate" which is basically saying that we don't know where the carbonate came from, but we're treating it as if it was calcium carbonate.  Same thing here.

When you have liquid or whey, there is usually some calcium phosphate dissolved in it (especially in raw milk).  This buffers the addition of acid.  If that runs out, or you drain off the whey, then you have to rely on the calcium phosphate salt in the curd.  But it takes time for the salt in the casein to be available in the liquid trapped in the curd.  Basically it takes time to dissolve.  If you acidify your cheese at the same speed that the calcium phosphate dissolves, then the pH won't change at all -- until you run out of calcium phosphate and then the pH will drop like a rock.  If you acidify more quickly than the calcium phosphate can dissolve, then the pH will steadily go down... until you stop producing acid, at which point the pH will go up!  That's because there is now calcium phosphate dissolved in the liquid and it can buffer the acid.

As I mentioned, you can use up the buffering capacity of your curds by waiting until you run out of calcium phosphate.  Because salts buffer to a particular pH (i.e. different salts will buffer acids and trend towards different pHs), once you get below the threshold (and held it long enough to know that there isn't more undissolved salt available) you know that you have no more buffering salt left.  I'm not exactly sure what the pH is for calcium phosphate, but the common wisdom is that if you hold your cheese at 4.6 or 4.7, then you will have reduced its buffering capacity.  So it won't rebound after that.

Thanks for the info/research! I'll let everyone know how this cheese turns out in about 9 months...

Just my 2 cents based on experience...
I have made Gouda with FD, MM100 and KaZU, by far the fastest acidification is with Kazu and the slowest (like seriously slow) is with FD. So since Aroma B and FD is similar, perhaps this can be a factor too.

I agree AnnDee


I used to make Gouda with other cultures, but my favorite is the Kazu by far. 
But it does acidify faster.

Quote from: cheesehead94 on August 23, 2018, 06:56:45 PM
Thanks for the info/research! I'll let everyone know how this cheese turns out in about 9 months...

So yesterday I cracked this guy open. I planned on aging it for 9 months, but since the make was so fraught with issues I decided to test it at 3 months...I figured there is no use in letting it occupy precious cheese cave real estate if it is a dud.

It tastes pretty ok! Sharper than expected for only being 3 months old, and a little bitter but not overly so. The texture is semisoft, but it isn't pliable like a Gouda should be, which is odd considering how the ph was on the high end for most of the make, and seemed to end up in the correct range when I put it in the brine.

After tasting this little slice I decided it was good enough to throw the rest back in the cave and stick to aging it for 9 months. I'll be interested to see how it develops.

Here are some pics (if there is some glare it is because I took a picture of the pictures I put on my computer and then posted them from my phone since I was having some computer issues)

Alrighty...it has been 8 months and 3 weeks, and I pulled this cheese out one week early to make room for another Gouda I made today.

So, I know on my last post  in this thread I said the taste was ok, but in the following days as I kept eating the wedge I decided that it wasn't very good. The texture was a little mealy, and they flavor wasn't great. I also was growing weary of the coconut oil rind maintenance. It sounds good in theory but didn't really work for me...the coconut oil flakes off really easily when you are wiping mold off of it, and it became difficult to maintain.

Discouraged, I decided to neglect this cheese. I know, I know, not my finest moment, but I did. I just left it in the cave, allowing anything and everything to grow on it, flipping and brushing once per week. I left the coconut oil on too, but eventually every type of mold you can imagine found a way to grow on it. It actually turned out kind of beautiful looking. In it's final two weeks a slime appeared, which I eventually figured out was due to water dripping onto the cheese. I stopped the water drip and ultimately i don't think it had much of an impact. This cheese seems to have shrunk the most out of any that I have made so far.

When I cut it open, there were lots of mold intrusions...I was able to salvage about 65% of the wheel though. The flavor is certainly not like any Gouda I have had. It has the mold flavor of a moldy cheese, texture isn't quite pliable but isn't dry or crumbly either. It isn't a cheese I could sit down and eat a lot of, but it isn't bad.

Overall, I wouldn't call this a success, but it isn't an abject failure! Definitely a good learning experience.

Oh, also...anybody have any idea how those big mold cracks form in the cheese? You can see it in the last picture of my previous post. I know that my curds weren't knit perfectly and a few mechanical openings were present, but those are some gaping cracks! I have to assume they formed during aging, but I'm not sure how that can be prevented.