Hi all,
I have my own cow and have a lot of trouble getting her milk to acidify.
Her normal pH is close to 7 (6.98ish). This is her norm, has been for the 2 lactations I've had her for. I culture her milk regularly and know it's not a mastitis issue, it's just the way it is. It also seems to buffer exceedingly well so I have a lot of trouble hitting pH targets when I'm supposed to.
The cheese I'm making right now is a Lancashire and I've been cheddering for over 2 hours and the pH is still around 6. I realized that I didn't check the pH at the time of draining which obviously would have been much higher than the 6.2 that is generally recommended. I used MA11, Aroma B and some Thermo C a lá awakephd's recipe. I'm grumbling and cranky as I feel like Im going to have a very dry cheese because of the whey loss with the prolonged cheddering.
So my question specifically is, if the pH isn't correct at the time it should be drained (end of stirring) should I just let it sit, maybe stirring occasionally until the pH is right?
Since she is so buffer-y, should I be increasing my amounts of culture? Half again as much to see if that gets me closer to targets?
Thanks for any thoughts,
Teresa
Just to double check...
Do you calibrate your pH meter each time with pH calibration fluid?
Are you measuring the curd or whey portion?
Hiya,
Yes to calibration (2 point, Extech) and I'm measuring the curd (as best I can by pushing the electrode into the curd).
Cheers,
Teresa
If you drain early there's not alot you could do. There is only so much lactose left in the curds and when the culture run out of food they stop producing acid. Under normal circumstances draining ph is in direct correlation to final ph.
But always check your ph meter, just last week I was in the middle of a make and found it had got out of calibration and I just about missed my draining target.
Hiya,
So if I find the pH is too high at the time I would normally drain, is the remedy to not drain and let the curds just sit in the whey (holding temp) until the pH drops? I'm just not sure what to do in this case.
Maybe increase temperature slightly to encourage acid production?
Stir once in a while so they don't mat too much but so they don't release more whey?
And then to try and reach targets on time, increase culture amounts?
Thanks again for any thoughts.
That's what I would do, but without your full make procedure it's my best guess. I'm not totally familiar with Lancashire but I'm guessing it in the family of cheddared cheeses. With that I pre ripen at 88 degrees for 1 hour, rennet per stir for 30 min cook to 102.5 in 45 then continue stirring at that temp for another 45 to 60 min. By that time my whey ph is at 6.3, that's where I drain and go on from there. I've found ripening temp and cooking temp are very important. I do 60 gallon batches so it takes more stiring then a small batch would. Hope some part of my ramblings has been helpful
60 gallons, wow!
I can certainly post the make if you want but basically ripening is 45 mins, Renetting was 50 mins (I used a flocc factor of 3.5, rest 5, stir 10, rest 5.
So not long for acidification to happen. There wasn't actually a target pH for draining stated anywhere I could see but there was for end of cheddering which is supposed to take between 30 and 60 mins to get to a pH of 5-7-5.4. Mine was about 2.5 hours. So I figured draining pH was likely too high.
This is a consistent issue with her milk; even when there is a target pH for draining, her pH is not even close to it in the suggested times so I was wondering how to deal with it. Your advice to hold is appreciated, I wasn't sure what to do. Still very much a newbie. I'll also try upping the culture by 50%.
Cheers,
Teresa
Did a quick search on new England cheese company
https://cheesemaking.com/collections/recipes/products/lancashire-cheese-recipe.
It does not list ph markers but he cuts the curds to 5/8 inch plus the short stiring would leave enough lactose in the curd to get to the proper acidity. I would definitely check his recipe out to see what he recommends for culture amount and cheddaring time, skimming his make it cheddared for 3 hours.
Best of luck
Interesting that the New England cheddars so long too.
I found this from Sailor when poking around some more which explains the short times:
"Lancashire is cheddared, but for a fraction of the time used for a true cheddar. With cheddar, part of the goal is to remove a lot of residual whey and build up acidity to a pH of around 5.4. This can take quite a while depending on the culture that you use. When the pH is right the slabs will have a texture like BBQ'd chicken. Then you mill and salt to stop acidification, hoop, and press.
Lancashire is an uncooked, moist curd cheese. You want to end up with a semi-hard, creamy cheese, so you only cheddar for a short time. I flip every 15 minutes for no more than an hour. Then you mill and salt. BUT, and here's the big difference, because of the shorter cheddaring time, the cheese does not build up the same acidity - say 5.9 to 6.0. As a result, the cheese will have a much softer texture than a cheddar. And because of the higher pH and moisture content, Lancashire ages much quicker. As I said, really good even at 60 days. Lancashire probably hits it's peak before 90 days, so I don't consider it a candidate for bandaging anyway.
After salting, I hoop and press instead of letting it stand overnight. I use light pressure (like a Gouda), and I get a fabulous curd knit. I don't feel that is cutting corners, because the salt has already stalled acid production anyway. I am VERY pleased with the results."
So looks like I might have made Lancashire according to the New England recipe or just some kind of cheddar according to Sailor.
I guess I made cheese
How have previous cheeses turned out?
What is her SCC count?
Hi Bantams,
I don't know her SCC any farther than her CMT is normal. Her cultures are all normal (last one was last Tuesday). Milk tastes fantastic.
Her milk for cheesemaking is somewhat frustrating. Fragile curd and poor yield. I get about 80% weight of what I should get according to recipes. She is AB AB for her cheese-related proteins so I assume that has something to do with it.
Other than that, always slow to acidify and so-so cheeses (but that could be me). Feta is awesome aside from the reduced yield.
Cheers!
Hmm... That sounds really strange. Usually raw milk from a Jersey will yield about 125-140% of stated yield in a standard recipe. And the curd should be exceptionally firm and durable. (My cows are all AB and have those high yields. Not trying to brag, just what I've observed working with several different herds' milk).
I think that a components and SCC test would be interesting to see.
How long is flocculation typically?
How do you chill the milk and how long is it stored before use?
Is it possible there's sanitizer residue on the equipment?
Yup I love my cow but her milk is a PITA! I wish I could get that yield! Brag away, I love to hear that, gives me hope for my next cow. Im waiting for her daughter to freshen so I can compare (A2A2, BB, AB)
I dont think there is residual sanitizer. Her TPC is/was consistently quite low (20s-40s CFU/ml) so I consulted with a RAWMI mentor and microbiologist and we went through my sanitation protocol and they thought it should be ok. I've kind of given up investigating because its been the same for 2 years no matter what changes I do. Having said that I just changed from hand milking to machine (repetitive strain injury) and her first culture on the machine showed the TPC went from 40 to 400. No pathogens. So still well within the norms for TPC but quite a jump. I also weaned her calf at the same time. The TPC might reflect me and the learning curve with the machine rather than her although its funny that I'm doing things that should reduce TPC and potential inflammation yet her milk remains the same pH and TPC went up. Im monitoring for trends.
Sorry, I'm not sure what you mean about component testing? Ill check into SCC testing, not sure how to do that but Ill see if the lab can do it at the same time as the culture.
I reduce the rennet just a bit and it gets flocculation to 11-12 mins.
Milk is processed immediately after milking, we chill in 2L jars in an ice bath, It takes 1.5-2 hours to get to 4C. Stored in a dedicated milk fridge that I monitor with a max-min thermometer and its holds temp right around 2-3 very nicely. Its good for at least 10 days although it rarely is around that long. I often make cheese with milk that is a few days old but Ive also made it with fresh out the cow and same results.
Thanks for helping me investigate this! Any thoughts that point me to the right direction are fantastic!
Teresa
That all sounds good! Component testing is usually performed by DHIA labs (or the Canadian equivalent). This is the test that registered herds do on a monthly basis to track the cows' production stats (butterfat, protein, etc) and SCC.
SCC and components are often paired. Our state DHIA lab charges $1.50 per sample and sends (free) reusable vials with preservative tablets (no need for ice when shipping).
Hopefully you can find a lab that does the same - it's helpful to know protein and butterfat values.
Got it, thanks!
I checked with our lab and they dont do it. The tech I asked there says we cant use the BCMMB (British Columbia Milk Marketing Board) as its only accessible to licensed dairy producers. Ill poke around a bit more but it might be out of reach for a single cow person like me.
I appreciate all your input!
Teresa
Its probably out of most people's price range for a home cheese making standpoint but there is a testing system you can use I've used it to figure out what cows on our dairy were trouble. https://nelsonjameson.com/PORTASCC-COW-TEST-KIT-96-TESTS-KIT-p61524.html
There's also the California mastitis test that is more reasonably priced and easy to use.
There not exact like a lab would have but they give you a good idea.
Just putting those out there
Hi Chetty,
Oh those look promising! It looks like there are smaller kits which might fit for small farmers if they have a long expiration date.
I did do a CMT (normal) but wasn't sure how sensitive it was.
Cheers,
Teresa
Here is my second attempt.
I followed the recipe as before; pH at draining was 6.7. Because I cant find any targets for draining pH for lancashire, i just went ahead and cheddared.
I cheddared until pH was 5.91 (I meant to do it at 6 but it started going down rapidly after it hit 6.2 so missed that) which took 1hr 45 mins then milled, salted, hooped and pressed. The curd was a very different texture at milling, much more what I imagine it is supposed to be at that pH. Moist without "chicken breast meat" striations.
Final weight 1.4kg so close to what I was supposed to get for yield.
I feel like after many attempts, I finally have made an actual style of cheese instead of just cheese. ;D
Teresa
Good looking cheese congrats on your success.
Beautiful - nice job!!
Thanks you both! ;D
Teresa
Though not my own cow, the farm where I volunteer typically has one cow that I am milking at any given time. It is interesting to see the differences in the milk from the different cows, and to see how the milk changes as they progress through the year or so of lactation, and season.
I have had a sort of similar experience with Henrietta's milk this cycle. Here is the long-ish story....
The Jersey cow being milked presently is about 2 months into lactation. She did have problems with clogged ducts at first, and some inflammation in two of her quarters. About 1 week after delivery, the first make I tried started at 6.6 pH, and had a firm set of the curd, with flocculation at 12 minutes, and a huge yield. Draining pH had been on target.
The next make was about 3 weeks later. On that make the start pH had jumped to 6.85, curd set was much more weak, and the flocculation took 28 minutes. Yield was closer to 10%. On another make a couple of days later the initial pH was 7, so I used extra starter, and extra rennet, and still had similar results.
I contacted the farmer, who then sent a sample off to be tested, and it came back positive for staph in one quarter. The CMT paddle test had not picked anything up.
After antibiotic treatment of that quarter had cleared, the milk I brought home was still testing high ( over 7) and my yogurt make had very thing set. So another sample was sent off, with the test showing positive for staph in another quarter! Antibiotic treatment proceeded for all 4 quarters.
To this week.... The milk is 10 days post completion of antibiotic, so safe to use, and clear for bacteria on repeated test. Initial pH was 6.85. I used about 50% extra starter, and more rennet than usual for the volume of milk. I ripened a bit longer than usual, flocculation was still long at 26 minutes, and stirring was longer and more gentle than usual. Draining pH was still higher than desired (6.65 versus 6.4). Final yield was 2.5# from 2 gallons.
I am hoping the milk will "normalize" in the coming weeks.
There are other elements to this story that I am trying to understand...
The calf has been left with the mama for suckling as desired. The cow is milked once a day, usually around 10 - 11 a.m. Her production on once a day milking (with a machine) continues to be very high - almost 4 gallons. So I am thinking this is a lot of stress on her udder tissues, and is perhaps a cause of the higher pH.
It turns out that the calf has been going to another cow for her milk! The other cow was supposed to have been dried off, but still seems to think she is the mama for the calf! Mama #2 has very fatty milk anyway, and so the calf probably likes her milk better as well!
So now an effort is being made to keep the calf and mama #2 apart from each other, and the calf should be nursing more from Henrietta, which to my thinking should help decrease the stress on her udder.
Regarding the milk and the cheese making process, my goals will be to test start pH, adjust cultures accordingly, likely increase the rennet amount, stir more gently for a longer time if needed, and accept a bit higher than desired pH on draining.
On the few makes I did in the past month, the pH in the press was much faster than desired even though draining pH was high. I think once the buffering capacity is overcome, the bacterial growth seemed to go really fast.
The CMT testing is still not showing any sign of problems. I believe the samples sent were tested only for bacterial growth.
I hope you will post more results with your cheese making efforts Teresa!
Was it Staph Aureus, or CNS (environmental coagulase negative Staph)?
At 10 days post treatment I would still expect a bit of inflammation/high SCC and the culture would almost certainly be negative because it is so soon after treatment.
If possible I would have them send off quarter samples for SCC. If any are high, reculture those ones in a couple weeks.
Hoping it's not Staph A as that is near impossible to eradicate (and contagious, so calves can spread it between cows).
She might be a poor candidate for once-a-day milking if she is overly full and having bouts of mastitis. Some cows just can't handle that much stress on the udder.
I don't know how much sway you have since she's not your cow, but a lab SCC test for each quarter would be really handy.
Yes Teresa, Susan, Chetty, and Bantams...I too hope you keep this thread going with your experiences. They have been invaluable to me, as for the past several years my milk sources have been via farmstead operations with various management techniques and I've finally figured out that I need a milk of a certain "quality" to make consistently good cheese.
I haven't been able to contact the one source that share milks yet produces high butterfat milk...to see what successful management protocols that she's been using, but will report back once I find out.
Bantams, the single common thread that repeatedly appears in your posts is the importance of SCC counts, regardless of other type of tests that result negative. So in your experience, are the 3 main factors to consider for cheesemaking perhaps butterfat, protein and SCC count?
I would say I was troubleshooting the cows' issues as much as the cheesemaking process, and SCC tells a lot about milk quality and cow/udder health.
High SCC causes pH to be abnormally high, so when troubleshooting cheese issues it's important to start with the milk before analyzing the make process.
When mastitis is an issue, it helps to know the SCC of individual quarters because sometimes a culture gives a false negative. SCC tests are cheap and easy so it's a good way to ensure an all-clear for each quarter.
If I were to assess a new source of milk, the butterfat, protein, SCC, SPC (standard plate count) and coliform counts would all be useful knowledge.
Bantams,
Are any of these tests you can do onsite, or on your own, or are they all lab tests requiring samples be sent off?
It sounds like lab test for SCC. Where do you usually send the milk for that.
The samples from Henrietta went to the vet for testing, and I don't think she did/does SCC count.
Apparently the cow thankfully did not have Staph A. Yay!!
SCC can be tested cow-side (or at home) with a Portacheck or CMT. I don't have much experience with Portacheck. The CMT is cheaper and more common but the threshold is 250k+. So it's great for showing acute mastitis cases but not necessarily going to detect a subclinical case. However, a SCC of 250k or below theoretically should not be an issue for cheesemaking. But some strains - like Staph A - can interfere with cheesemaking in other ways (enzymes, etc) but are hard to detect with a CMT since the SCC will often be right around 200-300k.
That's why I recommend a lab SCC test for situations where milk quality is questionable but the CMT is inconclusive.
Tests that can be done at home:
SCC (Portacheck or CMT)
Lacto-fermentation test (essentially a qualitative test that subs for standard plate count and coliform). Reflects milk quality after it leaves the cow - equipment cleanliness, chilling speed. I highly recommend this test for anyone using raw milk. (Have you seen how many people using raw milk have issues with coliform contamination?)
Lab tests:
SCC
Components - usually paired with SCC at DHIA labs
SPC/coliform - milk quality lab or food safety lab.
Milk culture or PCR - done to ID mastitis organisms. Sometimes done by a lab that also does SCC.
These can all be sent off by yourself, no vet needed.
If you need help finding a lab, I can help you find one.
Thanks, all.
Loving this thread!
Im looking into the PortaSCC as as far as I can find out there is no ability for me to submit to a lab. The milk board has quite the stranglehold on milk in the province.
Bantams if you can find me a lab in British Columbia Id be grateful as Ive checked with the dairy supplier, the raw milk study people one of who works at a local lab that does all the food safety and ag test, and people who have herdshares. No one thinks it is accessible to non-licenced dairies.
My cow's pH this morning was 6.99. Im making Leerdammer from 200 Easy Cheese recipes and holding at 40/104 until it gets to 6.3 as per Caldwell. Going on 2 hours now plus the 1 hour of stir time and its still at 6.78. :-\
Thinking about it, the cultures Ive been doing are for raw milk safety. They test for coliforms, fecal coliforms, Ecoli, Campy, Listeria and Salmonella Shigella. Not Staph or Strep. I wonder if I should submit something more tailored to a mastitis test.
I will check her CMT again this evening and if any question I will submit milk from that quarter(s).
So now I have another pH question so ill put it in another reply because I could use your guys' input on it.
Here is my problem today:
im making a large-eyed semihard cheese.
According to Caldwell the whey pH at end of cook should be 6.3-6.4. It never got anywhere near that. It was 6.75 at the most. I checked the calibration several times on the Extech and it seems fine. However the curds got squeaky and chicken breast texture so apparently they dropped. Im going ahead and hooping it now but can anyone explain the difference to me?
Thanks,
teresa
I've been pondering this thread and have thought of a couple of things, what temp are you calibrating your ph meter? Mine wont calibrate correctly if the solution is under 70 degrees farenheit. What is your calibration procedure? Do you use new solution, two or three point calibration does the solution in the probe look cloudy or low.
Other thoughts are how old is this cow?
Can you post photos of the cow in question and a close up of the ph meter probe.
I'm a visual person
That's really strange.
I don't think that holding the curd in whey for a substantially increased time is going to do any favors as the texture will be so different. But I also don't know a whole lot about pH deviations during the cheesemaking process. Hopefully someone else will chime in.
A couple other thoughts -
What do you use for culture? Source, type, etc. Wondering if it's ineffective due to age, temp shock during transport, etc. Was it purchased during the summer? Have you tried a mother culture, or a different culture source?
I know I asked about sanitizer residue already, but what type are you using on your equipment? Do you rinse before milking or not?
Have you tried something like yogurt or clabber with the milk? How does that turn out?
Just grasping at straws here...
I asked the cow discussion board about milk testing in Canada, no response yet.
The tests you've been running are food safety tests (E coli, Salmonella, etc).
If your cow is healthy and you have a good routine for milking and sanitation I personally don't think those need to be run regularly as the possibility of one of these organisms appearing in a single cow operation is so so low. But if you sell milk or need peace of mind they are good tests.
Those organisms typically appear because manure got in the milk or the cow is sick. Definitely smart for larger operations to test, but not really relevant in my opinion for a family cow.
QuoteMy cow's pH this morning was 6.99. Im making Leerdammer from 200 Easy Cheese recipes and holding at 40/104 until it gets to 6.3 as per Caldwell. Going on 2 hours now plus the 1 hour of stir time and its still at 6.78.
What temperature is the milk when you are measuring initial pH? Caldwell explains that cold milk will read a higher pH than when it is warmer. Assuming the milk pH is 6.99 at ripening start temperature, my deductions are that it is not going to reduce to 6.3 in the same time frame, if ever, as a milk with initial pH of the more normal 6.6.
QuoteSCC can be tested cow-side (or at home) with a Portacheck or CMT. I don't have much experience with Portacheck. The CMT is cheaper and more common but the threshold is 250k+. So it's great for showing acute mastitis cases but not necessarily going to detect a subclinical case. However, a SCC of 250k or below theoretically should not be an issue for cheesemaking. But some strains - like Staph A - can interfere with cheesemaking in other ways (enzymes, etc) but are hard to detect with a CMT since the SCC will often be right around 200-300k.
That's why I recommend a lab SCC test for situations where milk quality is questionable but the CMT is inconclusive.
To glean more understanding of how high SCC affects cheesemaking, I went back to Caldwell's "Mastering...." book. If I have this right, not only does high SCC affect pH, but the cells attack bacteria which may mean they are adversely affecting the starter culture...and thirdly, they produce enzymes which break down some of the protein structure which leads to poor cooagulation.
Again, Teresa and Susan, you are not alone in using milk with a high pH...I've done it quite a bit and as I say I do accept a bit higher pH targets than usual. I never have had a coagulation problem though. But what I don't understand is further in the process when pressing I get super quick pH drops and frequently I miss the ideal pH if I am not careful. I'm not sure if this is another piece of the puzzle or something entirely unrelated. BTW these cheeses come out OK, acceptable, meltable, good flavor but I would say the texture is a bit off...sometimes a bit too firm, sometimes a tiny bit chalky. It just seems weird to have issues with too high pH at the beginning of the make and too low/too quick at the end of the make. And wondering if it's the milk quality that is affecting all of these issues.
Milk testing in Canada...
Hope this helps.
https://familycow.proboards.com/thread/100070/milk-testing-canada?page=1#post-1063454
The Vermont Cheese Council is hosting their annual conference online this year (next Friday).
$65 for 6 speakers/topics, several very applicable to this discussion.
http://vtcheese.com/conference/ (http://vtcheese.com/conference/)
Hi all,
Thanks for all your thoughts. Sorry for delayed reply it was our once yearly snowfall and freezing temps so we are never totally prepared.
Chetty: Jez is 4 years old. I'll post some pictures. After you asked about the calibration fluid I realized that I hadn't changed it for a while. It was looking a little icky so I mar up a new batch. I was thinking about that as well. The solution for the "7" is actually 6.86. I couldn't easily find anything that was 7 and I think when in was researching it seemed that 6.86 was the standard for 7. If that is wrong I will go looking again. Maybe I need to bite the bullet and buy Extechs solutions. They are just expensive comparatively. I calibrate at room temp (about 20-22C), 2 point, 4 first then 7 as per the extech manual.
After I changed the fluid I checked some milk/cream combo 3L whole milk/1L cream) I was heating for cream cheese. The pH was 6.81 at about 25C which is the lowest I've ever seen it. I'm not sure though if the cream amount would alter the pH.
Bantams: yeah I'm not sure how this cheese will turn out, I just don't know what else to do when the pH is so far off what it's supposed to be.
Cultures are from biena or danisco. These particular ones were shipped in winter so should have been ok. It was ThermoC and proprionic. However it seems to be any culture I've tried. I've not tried a mother culture or yogurt.
Here's my milking procedure: pre rinse milker with about 10L hot water and a capful of bleach. Milk. After milking 10L lukewarm water rinse, then 10L chlorine based detergent rinse, then 10L acid rinse. They are dairy products.
I checked her CMT, nothing obvious.
Selling raw milk in Canada is illegal but there are many micro dairies that practice civil disobedience but with excellent hygiene and data (monthly cultures) as per RAWMI standards to back up the safety of their products. ;)
I did realize that the food safety package doesn't test for Strep or Staph so I many run a culture to rule out a sub clinical infection.
After reading your link, I will ask my vet if they can also run an SCC. Failing that I found a source for the PortaSCC which wasn't prohibitively expensive so I may order a small kit.
Susan38: my cheeses are "just ok". I'm not super happy with them. Texture is ok but they often to me have a weird under taste. No one else can taste it but I seem to be one of those super-tasters. Almost like the smell of plastic. IDK if that is related or not. So I'm investigating. I also have trouble knowing what amount of salt to put in as my yield is less and a lot of the recipes just call for an amount, not by weight of curd. I may be under salting for fear of oversalting so lately I've been using more salt to see if that changes the tastes. That's another story.
Thanks, all!
My goodness! She's a beauty!
Is she a show cow?
Has she ever had ketosis issues?
Do you supplement with Vitamin E when she's on hay (vs pasture, which has ample Vit E)?
Both ketones and Vit E deficiency will cause major off-flavors. Ketones will also cause high pH but it's typically a temporary thing as the cow will also be sick. But just thought I'd mention it as she looks like a big producer who maybe has trouble holding condition.
Thanks! You are now officially my favourite person for being enamoured of my cow ;)
She isn't anything aside from being lovely. She is actually a dairy reject. They couldn't train her out of sleeping in the gutter so wanted her to go to a home where she could have more pasture and a barn that didn't require free stalls.
No history of ketosis. She actually doesn't produce as much as I've seen many people post. Right now in the (relative) cold she is giving about 18L/day and when all is perfect about 21L. She has one quarter that doesn't produce nearly as well as the others. More than enough for us though!
She gets organic grain, organic alfalfa pellets, kelp, dairy minerals, medium quality hay and a big flake of high quality hay at each milking. They have a high selenium salt/mineral lick available. No off flavours in her fresh milk. No vitamin E but I recently came across that on some cow boards and was considering it. Do you have a dose for that? If its not off the top of your head, no worries I'll look it up.
She's not too bad of a keeper. The herdsman who came an AId her was quite surprised at her (good) body condition. I guess he's used to seeing cows a whole lot skinnier than she is.
Cheers,
Teresa
Looking at how pretty that cow is, my money is on the ph meter. I have a love hate relationship with them when they work there great but I've owned 4 different brands different price ranges and still haven't found one that I trust 100%. My current meter was a 300 dollar spear tip meter. I've had to replace the probe which was another 200 dollars and I still have trouble. I have not had the brand you use but I think I would start there. New calibration fluid check Amazon you can get some reasonably priced. Clean the probe sensor check the glass over there is a tiny spot on the glass that is most important to be clean as it is where the testing occurs.
QuoteI calibrate at room temp (about 20-22C), 2 point, 4 first then 7 as per the extech manual.
I have an Extech 110, maybe different model than yours, but the instructions for mine are to calibrate at 7 first, then 4. I think I did it the other way around once, and the subsequent measurements were way off. Could the problem be as simple as this?
That's how all my different ones were calibrated too. In fact mine wont let you do it any other way it looks for 7 then it searches for 4.
Interesting. I will double check as I even wrote on my jars 4 first.
OMG seriously?!? It does say 7 first. Facepalm. I love you guys.
Will report back...
pH meters are notoriously hard to calibrate/clean. I've owned 2 in the past. When I started cheese making, even though I knew the advantage of using a pH meter I decided it was easier to go without. With your own cow, I think it's definitely a thing you want, but I recommend assuming measurement error before you wonder what's wrong with your cow/milk. Especially if your make is proceeding normally, that's a good indication that your meter is just not giving you good readings.
A couple of tips: The probe has to be immaculately clean. Salts on the probe will basically screw everything up, as will fats and proteins. Don't store your probe in tap water. Different probes have different care requirements, so be sure to follow the instructions carefully. To get the best measurements, you probably should clean and calibrate the probe before every use. Some probes are more finicky than others, so you may need to do it or not. If you are getting weird results, assume the probe is dirty/miscalibrated/damaged unless you have some other factors to back that up (as frustrating as that sounds).
pH also depends on temperature and the temperature you calibrate the device at is very, very important. Some devices have a temperature probe and adjust for temperature, but you still need to be careful about the temperature you calibrate at -- because the temperature probe may not be correct. Always measure temperature with a different (tested) device. Good digital thermometers can be calibrated as well, so do the boiling water/ice water calibration on it. Even if it can't be calibrated, make sure to test it because some devices are off by a huge amount (this will help your cheese making too). When calibrating your pH meter it is very, very important to follow the directions for the temperature of calibration exactly, because it will differ depending on the device.
A very important point: if your device does not automatically adjust for temperature, you must do so manually. Otherwise your readings will just be wrong. So you calibrate at a certain temperature, take the temperature of your sample, measure the pH, look up the *actual* result in a table (which hopefully came with the device -- otherwise I think there is a table in Caldwell's book, or you can look for one online).
When making cheese, there are several points in the process where you can get a gut feeling for pH. Learning to understand these helps a lot (and is pretty much necessary if you don't have a pH meter). Here are a few pointers:
Milk coagulates due to acid at different pHs depending on the temperature. Roughly, at room temperature it's 4.6, 50 C is 5.2, 80 C is 6.0. Those are not correct -- I wish I could find a good table of actual values, but they are close. This means that you can test your milk simply by adding a starter culture and occasionally heating small portions of it to various temperatures over time. Then you can cross reference that with your pH meter to see if it is agreeing.
Similarly ricotta cheese forms best at a pH of 6.0. A good test of your drain whey pH is simply to make ricotta. If it doesn't start to curdle at around 85 C then it is up over 6.0 by a fair way. If it curdles nicely at that temp, then you know you are around 6.0. If it gets grainy and sinks to the bottom, you know you are under 6.0 by a fair way. (It's a fair whey that tells you it's own pH...)
Rennet coagulates milk at a fairly regular rate depending on rennet amount, temperature and pH. So you can get a feeling for the pH of the milk simply by measuring the flocculation time (assuming your rennet is in good shape). Always measure flocculation time using whatever method is most consistent for you. That way when it changes you know that something is wrong -- likely with the pH of your milk.
However, you can also do experiments on flocculation time. Add a starter culture to milk. Pour the milk into several small containers with a wide mouth (like coffee cups -- 250 ml each). Hold the temp at 36 C in a water bath. At regular intervals (say every 30 minutes) add a drop of rennet (which will make it 40 IMCU per liter) to one of the coffee cups. Put a soda cap in the cup and measure the time to flocculation (for me that's until it won't spin any more and it *just* leaves a mark when I take it out -- that's a bit longer than most people, I think, but it is repeatable for me). Record the flocculation time and measure the pH. This will give you a good sanity check on the pH. I forget what the standard is, but I *think* it's something like 12 minutes at 36C and a pH of 6.5. If your pH measurements are way off, it will be pretty obvious. BTW, this is literally how they define IMCU, though there are other testing methods you can use as well.
The taste of milk changes as the pH drops as well. This is pretty subjective, but I've been surprised at how much control I can get. I'm actually pretty good at detecting sugar. I used to brew beer a lot and when I was active I could actually tell you the specific gravity of the wort within about 1% either way just by tasting it. Practicing tasting can give you a pretty powerful diagnostic tool.
Milk is sweet due to the lactose in it. As the starter culture metabolises the lactose, that sweetness goes away. In its place you get acidity. Sweetness is much, much easier to taste than acid, unfortunately. When I first started, I lamented the fact that I couldn't really discern acidity very well. It wasn't until I read Jim Wallace's description that I realised the trick -- concentrate on sweetness.
At a pH of 6.0 or higher, milk tastes like milk. As the culture gets established, I find that around 6.0 I can start really picking up the aroma of the fermentation products -- this is probably not to do with the acidity at all, but it can tell you how active the culture is. Below 6.0, it starts to get less sweet. As is gets less sweet, you start picking up the milk fat flavour in the milk -- previously it was masked by the sweetness. As it goes lower, you start to pick up a little bit of bitterness. Again, the natural bitterness of the milk is masked by the lactose sweetness. There is also a phenomenon of bitterness-sourness confusion. Things that are sour at a low level are often perceived as bitter. So if you are picking up on that bitterness, it's because the sugar is going away and the acidity is coming up. At about 5.4 - 5.5 the flavour is neutral (I don't know exactly, because I don't have a pH meter :-D ).
As the pH goes down from there it starts to pick up more acidity. It is much easier to measure the pH of the whey than the curd, so you should always measure the acidity of the whey as a sanity check against the curd, IMHO. There are a couple of problems, though. The whey has been draining over time, and will acidify differently outside the curd than it does inside the curd. The curd contains protein (duh ;-) ) and protein tends to buffer the pH. This means that the pH of the curd is always *higher* than the pH of the drained whey. So don't be confused when you measure it and that happens. Strangely someone mentioned that when they measure they get the opposite and I'm not sure what that means :-) Possibly that their probe doesn't work very well for curds... You can also verify this by tasting. Especially just when the whey is getting tart, the curd will still have a neutral/buttery flavour.
Finally, the curd undergoes changes as the pH drops. I wish I could remember who explained this to me (on this very forum!) because it blew my mind at the time. Curds knit more or less easily based on 3 factors: pH, moisture level and temperature. Despite all my preconceived notions, that is the actual order of importance (at least at temperatures under the melting point of the curds). pH is king. Nothing has improved my cheese making more than understanding this point.
At a pH of 6.0 and above, curds knit very, very fast (from separate curds to a consolidated slab in 15 minutes with no weight on them). At a pH of 5.3, they don't knit at all unless they are very high moisture, very warm and/or have a fair amount of pressure on them. You can guess the pH of the curd simply by watching how the curd is knitting. If your pH meter is reading 6.0 for the curd, you can just cut it and stack it and see if it melds into a slab in 15-20 minutes. If so, then the pH meter is right. If not and they just sit there as two pieces, then the pH meter is wrong.
I hope some of these tips are helpful!
Hi all,
After making sure my meter window was clean and calibrating it correctly, pH of fresh milk cooled to room temp 22C was 6.89. So still a bit high.
My vet is going to run SCCs for me and we are also going to culture for organisms outside the food safety screen.
Mikekchar: thanks for your detailed reply. Her milk is frustrating and makes have not gone as they should have which is why I got the meter. Trying to science her milk.
This probe does have a temperature sensor. My three thermometers are ice bath calibrated and agree so at least I got that.
The meter so far seems to be accurate with the things I make at room temp like cream cheese. I often miss the actual point of first coagulation (there is a lot of whey on top by the time I get to it) so it's sat a bit too long and the meter was giving me a 4.5-4.55 so I thought that seemed right.
The flocculation test seems easy for a meter check. I'll try that. My determination of flocculation is like yours and it's usually right around 12 minutes at 30C if I use the recommended amount. I was reducing the rennet amount a bit but my last few makes the flocc time increased to 14 mins so I'll go back to the regular amounts.
Is doing the 36C flocc several times just so you can see if you have repeatable results for pH?
I think that was me with the whey apparently being 6.6 but the curds said they were 5.3ish as they had that cooked chicken breast texture. They also took a shwackload of pressure to knit so they were obviously way down there.
The other tips are also great. I'll try to put some of them to use in my next batch!
Cheers,
Teresa
Small update,
Cultures for Staph and Strep came back negative. Their SCC counter was sold by the boss unbeknownst to my vet so he is looking into where I can get SCCs done.
pH at 19C today was 6.81. A farmhouse cheddar make went reasonably well pH wise but I did add half again as much culture.
Cheers,
Teresa