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GENERAL CHEESE MAKING BOARDS (Specific Cheese Making in Boards above) => EQUIPMENT - Making Cheese => Topic started by: Nitai on April 19, 2011, 10:55:20 PM

Title: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Nitai on April 19, 2011, 10:55:20 PM
I asked this elsewhere recently but there were no responses, so I am asking again because I am a persistent bastard :)

I have an extech 110 with the flat electrode, but I find when trying to test surface PH of a wheel that has been pressing for a while the reading leaves me uncertain. It seems to fluctuate more than it does in liquid and I just never trust it. I know I can collect whey and test that, but I am doubtful that it acidifies at the same rate, especially because I imagine it cooling more. Thoughts, suggestions?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Boofer on April 19, 2011, 11:29:29 PM
Dear persistent bastard,  ;)

I am certainly no expert on pH testing, but here's my experience:

I have an Extech 100. Virtually the same device except that you don't refill it like you do with the 110. In my most recent two wheels I removed the wheel from the press and pressed the flat electrode perhaps 1/4 inch into the top of the wheel. The reading stabilized after a couple seconds and I took that as my reading. The surface of the cheese wasn't damaged and sprang back after I was finished. The pH reading has to be done where there is some residual moisture. The surface you're trying to test cannot be dry. Since I had just removed the wheel from the press, this was okay. If I had waited until it had air-dried, my meter would have had a difficult time trying to register a pH.

Hope that helps.

-Boofer-
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Nitai on April 19, 2011, 11:46:13 PM
Thanks boofer. That is what I have done too, but I suppose maybe mine stabilizes a bit slower and I am an *impatient* persistent bastard (slightly oxymoronical, I know). I'll see how it goes tomorrow when I test the Asiago that is in the press. I also can't help but think that the internal PH in a wheel might be different than the outside...
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on April 26, 2011, 01:35:42 PM
I have to admit that my fancy Extech 407227 spends most of its time in the box for those exact reasons. It takes about 20 minutes to calibrate this piece of junk (and it has an automatic temperature compensation and thermometer electrode... but that needs its own calibration too).  Once I finally have it figure out I hate sticking it in my cheese as it does leave dents and holes that later become clogged with wash or whey and develop mold.  I didn't want to spend $100 for the flat electrode considering how lame this whole instrument is.  During calibration the numbers are inconsistent and fluctuate wildly for several minutes.  I dip it in 7.00pH liquid, get a 6.56 reading, shake it a bit and it goes to 7.7pH reading etc. Adjust it to 7.00ph. Wash the liquid off, dip it in 4.01pH liquid and get 3.4pH, shake it, it jumps to 4.6, adjust it to 4.01ph. wash the liquid off, dip it again in the 7.00pH liquid and the reading is now 6.7pH, adjust it again. Now the 4.01liquid shows as 3.9pH and so forth until it stops fluctuating.

By the time this nonsense is done either my cheese has gotten over-acidified or I missed cutting the curd.  Even when it's finally balanced, I stick it in the cheese and it reads 5.2pH. I do it again 5 minute laterand it shows 5.6pH, I do it again and it shows 5.1pH.  As you can imagine, more often than never, the pH meter guarantees I will mess up and spoil the cheese rather than actually help control its quality.  This isn't my meter; my $30 Hanna Checker (Hi98103) acts no difference, only here I have to calculate with a separate thermometer.  I feel that the only solution is industrial food lab meter with automated calibration and compensation and those are $1,000+ instruments.  Very frustrating
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Nitai on April 26, 2011, 04:40:14 PM
Sounds like your Extech is a lemon!  :o
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: ArnaudForestier on April 26, 2011, 05:31:55 PM
Sounds like your Extech is a lemon!  :o

Man, I am loathe to jinx this, as I had such horrible luck, but, if we're talking lemon,

my 3rd Extech seems to be performing brilliantly, equally well in liquids, curds/whey slurry, or finished wheel.

-He says sheepishly, begging the H+ ion gods not to curse him for his turophilic hubris.  A)
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 26, 2011, 05:37:26 PM
Yoav, if you're experiencing oddity, condition your meter, and if it still doesn't work, send it back.

To condition

- First remove oil. Do this by washing with regular detergent. Soapy water
- Second, remove protein. Do this either by soaking in 1% pepsin/rennin with HCl added (.1 M... about 2 pH) to activate it; or if you don't have pepsin/rennin, use those enzymatic contact lens cleaner solutions like Renu. They work just as well and are really cheap.
- Third, remove salts. Do this by soaking in an acid solution. Something like .1 HCl, or even vinegar, or citric acid.
- Fourth, unplug everything. Do this by soaking the end of the probe in hot, 80C saturated KCl solution (3-4 M concentration)

The big one is protein and KCl. If you do that and it's still wonky, not too much more you can do. except refill the reference solution, and/or replace the junction.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Boofer on April 26, 2011, 06:55:42 PM
if we're talking lemon,

my 3rd Extech seems to be performing brilliantly, equally well in liquids, curds/whey slurry, or finished wheel.

-He says sheepishly, begging the H+ ion gods not to curse him for his turophilic hubris.  A)
Now you are challenging forces just beyond your grasp. If you're not careful, they may set the clock on your camera to the correct date.  ;)

I have reached an agreement with my ExStik. It only comes into view at certain moments when I am sure it won't screw up my cheese. I have substituted incense and chants to make it somewhat successfully through a make. I have confidence that guided me last Friday with my Goutaler.

-Boofer-
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on April 26, 2011, 09:44:36 PM
Linuxboy - I am afraid these instructions and most of the acronyms are beyond my understanding.  That's part of the problem of using pH meters in my opinion; it is easier to pre-flight check a Cessna 206 and trust your life to that hunk of junk in the sky than it is to condition this thing and trust it will work.  The Extech 100 may be easier to use because the probe is flat and wont poke holes in cheese (and easier to clean). It's a bit more modern. 

I don't think my unit is a lemon. What I describe is my experience with every pH meter I've ever used.  How do you use yours? Do you just put in pH solution, turn a screw to the right number, rinse and do again in the other pH solution and then you rinse and ready to go? In a perfect word this should work but this seems to never work that well. (I never understood why you need to use that screw. It's a computer; why not just tell it you are looking for the number 7.00???)

Boofer - I hear you.  I practice looking, feeling and smelling the curd. There is 7,000 year track record for doing that before pH meters came along. It would be great if this was something I can use as a reference for my commercial recipes and to replicate success and track problems, but realistically when you have a meter that shows your 7.00 pH solution as 7.00 one minute and 2 minutes later it thinks it's 6.7ph - it obviously cannot be trusted to tell you if your cheese is 5.2pH or 5.5pH.

My meter by the way is a heavy duty portable lab model.  Does anyone here have a pH meter they actually trust and can be calibrated in less than 2 minutes and keep calibrated for more than 60 minutes?  Am I asking too much?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: ArnaudForestier on April 26, 2011, 09:57:24 PM

Now you are challenging forces just beyond your grasp. If you're not careful, they may set the clock on your camera to the correct date.  ;)

Hahah...OK, OK, I promise I'll uh, remember to change...uh....what was I supposed to change again?  ;D

I have reached an agreement with my ExStik. It only comes into view at certain moments when I am sure it won't screw up my cheese.

I have substituted incense and chants to make it somewhat successfully through a make. I have confidence that guided me last Friday with my Goutaler.

-Boofer-

Boof, was that a clockwise incantation, or counterclockwise?  And a white, or black athame?  Just curious, cuz' crying seemed to work well for me with this third demon, but I could use a backup, for sure.   8)
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 26, 2011, 10:07:16 PM
Quote
Linuxboy - I am afraid these instructions and most of the acronyms are beyond my understanding. 
Oh. Well HCl is hydrochloric acid. KCl is potassium chloride. Molarity you don't have to worry about, I included it here only for reference. The rest I thought was straightforward? Rennin is about the same as rennet. You can buy all these products prepackaged. Hanna sells all of them, for example, if you want to spend the money.

Not sure what's not clear about first washing with soapy water to remove oil, the soaking in Renu contact lens solution to remove protein, then soaking in vinegar to remove salts, and finally heating some water, dumping in potassium chloride until no more will dissolve, putting the meter in there and letting the water cool down?
Quote
I don't think my unit is a lemon. What I describe is my experience with every pH meter I've ever used.  How do you use yours? Do you just put in pH solution, turn a screw to the right number, rinse and do again in the other pH solution and then you rinse and ready to go?

Yes, except screw? You mean calibrate? Often, I don't even calibrate because my probes keep their calibration. But, I do take good care of the probes using the details specified for cleaning and maintenance.
Quote
My meter by the way is a heavy duty portable lab model.

Do you take care of the probe?
Quote
  Does anyone here have a pH meter they actually trust and can be calibrated in less than 2 minutes and keep calibrated for more than 60 minutes?  Am I asking too much?
All of mine do that.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Nitai on April 26, 2011, 10:12:54 PM
I have an extech110 and it works quite well. After 3 months unused it registered PH7 solution at 6.9, and steadily. In the course of a cheese make I usually break it out, was gently with soap, dry, leave to sit cleaning solution, rinse, dry and use. If I calibrate I do it before use. Afterwards I wash with soap, dry, and cap it again. I know I am not up to Linuxboy standards, but so far my ignorance has been blissful.

Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 26, 2011, 10:28:39 PM
I don't do all those every make. It's an approach for each issue. If you have protein buildup, use an enzyme. If there's fat stuck, clean with detergent. If you left it sitting out and the junction dried up, soak in some KCl. If your reference liquid is fouled up, then replace the reference liquid. In cheesemaking, though, the biggest thing I tend to find is protein. Every so often, I'll need to let it sit and let the enzymes do their work.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: David Helmers on April 27, 2011, 08:32:12 AM
I have an Extech 110, and I'm quite happy with it. I calibrate it in 4.0 and 7.0 buffer before each make. I find that the reading flashes all over the place until it adjusts to the temperature, then it gives a stable reading. I keep it standing in water about the same temperature as the milk so that I can get a quicker reading because of this. I make sure that the cap is wet before storing, and I always store it upright. On cheeses that I've made a number of times I can go by sensory input, but if it's a new style or one I haven't done repeatedly the meter is my good friend.
Dave in CT
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Boofer on April 27, 2011, 08:46:24 AM
I seem to be developing an understanding of how to utilize my ExStik 100. It calibrates fine in the reference solutions. It seems to display a reasonable reading most of the time.

The problem is that I could take a reading during ripening, wait for a period of time, and take another reading. This latest reading may be significantly higher than the previous one, which makes no sense because I expect for the reading to be dropping...not climbing. A subsequent reading a short time later may then come back to where I would expect, showing lower...reasonable because the acidity is increasing. This has happened on several makes. I have come to expect that anomaly and I try to adjust around it.

Other readings seem reasonable: at rennet time, wash time, before the pressing, after the pressing. Those do make the meter useful and offer some confidence. Following guidance (probably Iratherfly's and linuxboy's) here on the forum, I am trying to develop a sense for the milk, curds, and cheese and everything that affects them. The meter is a tool to assist me along the way, but it is not a crutch. I do not rely solely on it to tell me what the make is doing.

Iratherfly, as far as I know, on the ExStik there is no user adjustment. It either works or it doesn't. Linuxboy's directions on proper electrode maintenance should be recorded somewhere in the forum as a reference for future meter diagnostics. Very clear.

-Boofer-
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Queixo on April 27, 2011, 03:43:58 PM
My pH meter is a PH-200 (http://www.tdsmeter.com/products/ph200.html), in the same price range than the Extech. Its readings are clearly wrong, it can go from say, pH 6 to pH 6.5 if the temperature of the liquid being tested drops 5C, despite having ATC and its temperature readings being spot on (checked with a thermometer I trust).
Can this behaviour be caused by a bad probe, or do I have to blame the main unit and think about getting another pH meter?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 27, 2011, 04:12:17 PM
Most often, lack of a stabilized reading or jumps are caused by clogged reference junctions. When protein, fat, or salts clog it up, the reference solution (usually KCl) cannot flow. And sometimes it will go the other way, where whatever you're measuring will flow back up into the electrode, fouling it up. What you need to do is follow the procedure I listed to try and clear up the junction.

Some junctions are better suited than others for dairy. For example, high quality ceramic or teflon tend to work very well and do not clog easily.

This is why proper care is so vital. If the protein gets caked in, no matter what you do, you may not be able to unclog the junction, and then you have to replace them or the probe.

One of my most trusty probes has a double junction and stabilizes really fast. I get a reading in under 10 seconds most of the time.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on April 28, 2011, 03:35:35 AM
Linuxboy - thanks for clearing this up. Except for the potassium chloride I seem to have everything (though I have rennet, not renin) and the rest of your instructions are clear. Thanks for following up on this.

so... Last night, following this discussion I fired it up to check on a new type of washed rind cheese I am working on. It's 24 hour old, (not yet salted).  According to my calculations it should have been at 4.6 pH. I cleaned the probe well with warm water and detergent, then with rinse liquid. I then stuck it in the cheese (seriously, these poke marks are becoming part of the presentation aspect of my cheese).  The reading was clear: 4.6pH wait, no 4.7 ahh, 5.1, 5.0, 4.6 again. Okay Most of the time the number was indeed 4.6 which was perfect. The fluctuations in the numbers seem to have been affected by movement of the probe and I needed to rest it for 30 seconds or so to stabilize the reafing.  As I moved it I saw water moving in it (it's a clear probe where you can see the wires). It seems that water has penetrated it when I cleaned it (or some liquid is supposed to be there and I've never noticed it before???).  I would assume this confirms that this probe is defective.  Wouldn't you say?

I still don't know what's the deal with my Hanna meter but it's a cheapo meter so maybe I should get a new one. I think that a ExTech ExStik 100 or 110 may do the Trick. They have flat probe as I understand it, and no futzing around with a screw to move it to 7.00pH or 4.01pH when calibrating. Perhaps my meter is just old.  The thing is that the flat food probe for my meter costs as much as a brand new ExTech 100 anyway so maybe I should just get that.  I wish I could afford the Hanna HI 99161. $350 is more than I wanted to spend but it's a quick pH meter that is made especially for dairy.

But the real lesson is that I had a cheese arriving at its proper and exact acidity levels at the right time without using any pH meter to begin with.  I think this is because I learned to "feel" (look, smell, taste) the milk, whey and curd. I pay attention to the room conditions and I time the cheesemaking stages correctly.  The more I do it, it seems the higher my success rate is.

Yes, I know that if I want to get serious about producing the cheese or certifying others for some of my originals I must get used to using the meter for consistency and as a safety control point for HACCP purposes. I do love that I have eliminated any dependency on this instrument for production of quality cheese and I just keep it as a control and alert point.  In flying it's called Pilotage - the skill to fly by visual landmarks and by feeling the aircraft and environment. You have to perfect it before you can move to instrument flying.

In any case... any recommendations on what meter I need to purchase? Anyone?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 28, 2011, 08:15:15 AM
Quote
(it's a clear probe where you can see the wires). It seems that water has penetrated it when I cleaned it (or some liquid is supposed to be there and I've never noticed it before???).  I would assume this confirms that this probe is defective.  Wouldn't you say?
That's the reference solution inside the probe. Usually saturated KCl. Why do you think it's defective? There's no way to tell if it's fouled up except to take a sample of it and test for impurities.

Rennet IS mostly rennin. All I meant is you need an enzyme to clean the proteins. Use contact lens solution if you're unsure. Buy some KCl. It's cheap and makes for great storage solution and is useful in conditioning meters.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on April 28, 2011, 11:25:44 AM
I think it's defective because my readings are unstable and jump very quickly from 4.6 to 5.1, back to 4.7, 5.0 and 4.6 again etc.  It feels very volition and unstable.  Is that normal that the numbers keep changing on the screen when your probe is stuck in the cheese for 2 minutes already?  The numbers don't change towards a stable reading but are just all over the place.

What meter and probe brand do you use or recommend?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 28, 2011, 11:58:02 AM
That jumping around is not necessarily a fouled reference solution. When the reference solution fouls up, the meter becomes uncalibrateable. It consistently reads a bias, or it will never fully stabilize. I think you have a clogged junction and need a good soak in acid and then KCl. Real fouling is somewhat rare. Clogs are far more common.

I like ISFET probes because they're easy to clean. If not then, then flat tip or spear ones. But those get so expensive. The Extech is a decent middle ground when it works. I don't like everything about it, but it does alright if you get a good one.

Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on April 28, 2011, 12:56:30 PM
My understanding is that ISFET probes do not need to be stored in solution ...but are very expensive.

My issue with the whole thing is
when it works.
If I use a pH meter I would do it for professional reasons and want one that is accurate, reliable and fast. It would be pointless to use any pH meter that cannot perform consistently. Being 0.2pH off is enough to mess up batches of otherwise good cheese.  In other words, I need to trust it and make decisions based on the reading rather than just use it for logging.

I found these specialized Hanna probe cleaning solutions for dairy and cheese when poking online (what on earth is the difference?)
http://www.hannainst.com/usa/prods2.cfm?id=002002&ProdCode=HI%20700641P (http://www.hannainst.com/usa/prods2.cfm?id=002002&ProdCode=HI%20700641P)
http://www.hannainst.com/usa/prods2.cfm?id=002002&ProdCode=HI%20700642P (http://www.hannainst.com/usa/prods2.cfm?id=002002&ProdCode=HI%20700642P)

Thoughts?

What do you think of the Hanna HI 99161?  It seems ideal but WAY over budget ($350-$400):
Video: HI 99161N Dairy pH meter (http://www.youtube.com/watch?v=twr_Xsj9omQ#)
Details: http://www.hannainst.com/usa/prods2.cfm?ProdCode=HI%2099161N&id=002002 (http://www.hannainst.com/usa/prods2.cfm?ProdCode=HI%2099161N&id=002002)
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on April 28, 2011, 01:24:21 PM
Quote
My understanding is that ISFET probes do not need to be stored in solution ...but are very expensive.
Not true. That's just a marketing claim to get people to buy them. Yes, if you use the meter every day, and the junction stays hydrated, you should be OK with dry storage. Meaning, there's no bulb, so the issue of bulb hydration is moot. But if you're not using the meter regularly, then you must store in either KCl, or a KCl with 4 buffer in it.

Quote
want one that is accurate, reliable and fast.
All meters have their quirks. And all meters require maintenance. Some more than others. And all meters fail, and all meters need their probe replaced with use because over time, there's drift. Not avoidable.

Quote
probe cleaning solutions for dairy and cheese
This is HCl and an enzyme, such as pepsin. They use the same formulation I detailed. It is an industry standard to remove salts and proteins. The HCl also lowers the pH to activate the pepsin. If you soak in an enzymatic cleaner you make yourself, it does the same thing. IMHO, you can buy it if you want the assurance that it's "official". Sort of like having organic certification vs not when you know the underlying product is the same.

That Hanna is a pretty nice unit. It works OK. In my experience, my Oakton with ISFET stabilizes faster. If I plug in a regular double junction probe, it performs about the same. If you take care of the probes, most commercial meters work well (except cheap stick types). I'm personally a fan of using dedicated handheld units, and then replacing the probes every so often. Because then the probes run $100 or so. Of course, if you get a working Extech, their probe replacements are cheap... $50. And they also sell junctions for them.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on April 28, 2011, 01:45:25 PM
Thanks! That's some great info!
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: lwybrant on May 02, 2011, 08:41:15 PM
Has anyoone used ph test paper with success?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Helen on May 02, 2011, 11:18:52 PM

Quote
Has anyoone used ph test paper with success?

PH papers are unfortunately not accurate enough for cheese making.

- Helen
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on May 05, 2011, 09:13:47 PM
I thought they were accurate ...if you know what range to look for. You need the right paper for a small range of pH at every test. That means you would use something else for 5.5pH and for 4.6pH and that's a bit wasteful and very expensive.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: arkc on June 03, 2011, 12:47:50 PM
I bought an Extech 110 about one month ago and it was defective.

I just called them and without any argument, they are sending me a replacement
without my having to send the defective one back.  AND they are sending it UPS 2nd
day at their cost.

NOW THAT'S WHAT I CALL GREAT CUSTOMER SERVICE!!!

annie 
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: iratherfly on June 04, 2011, 12:52:32 AM
That's great. I should call them about my own wacky heavy duty lab Extech. Only it's a 7 year old model  :-\  never worked right.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Beans on February 08, 2012, 10:42:34 AM
That jumping around is not necessarily a fouled reference solution. When the reference solution fouls up, the meter becomes uncalibrateable. It consistently reads a bias, or it will never fully stabilize. I think you have a clogged junction and need a good soak in acid and then KCl. Real fouling is somewhat rare. Clogs are far more common.

This is probably a silly question but what is KCI?
-Beans
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on February 08, 2012, 11:21:07 AM
Not KCI, KCl. Potassium chloride.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Beans on February 08, 2012, 12:11:14 PM
Not KCI, KCl. Potassium chloride.

That makes more sense.  Thanks for the info.
Beans
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Spoons on November 10, 2013, 06:20:42 PM
Yoav, if you're experiencing oddity, condition your meter, and if it still doesn't work, send it back.

To condition

- First remove oil. Do this by washing with regular detergent. Soapy water
- Second, remove protein. Do this either by soaking in 1% pepsin/rennin with HCl added (.1 M... about 2 pH) to activate it; or if you don't have pepsin/rennin, use those enzymatic contact lens cleaner solutions like Renu. They work just as well and are really cheap.
- Third, remove salts. Do this by soaking in an acid solution. Something like .1 HCl, or even vinegar, or citric acid.
- Fourth, unplug everything. Do this by soaking the end of the probe in hot, 80C saturated KCl solution (3-4 M concentration)

The big one is protein and KCl. If you do that and it's still wonky, not too much more you can do. except refill the reference solution, and/or replace the junction.


Revisiting an old thread  :o

Some of these instructions are clear, but I still need some reassurance.

Step 1: Remove oil
Clean in soapy water. Easy-peasy... but isn't the probe too sensitive? I have an Extech PH100. For some reason, I thought I had to avoid touching the tip of the probe. I need a bit of reassurance here...

Step 2 : Remove protein
I found this product ( http://www.walmart.com/ip/Renu-Daily-Protein-Remover-Liquid-1-Step-Tm-0.17-fl-oz/10533128 (http://www.walmart.com/ip/Renu-Daily-Protein-Remover-Liquid-1-Step-Tm-0.17-fl-oz/10533128) ), but the directions for cleaning contact lens says to just add a drop in an other lens cleaning solution. So do I just need to add a few drop in an ounce of distilled water? or do I need to get both solutions? How long do I soak? Also, what about this product? http://glengarrycheesemaking.on.ca/access.htm (http://glengarrycheesemaking.on.ca/access.htm) . Seems to me it takes care of steps 1 & 2 easily. Pretty cheap too!

Step 3 : Remove salts
Soak in vinegar. No prob.

Step 4 : Unplug everything
Is there a household product I can use for this? and how would I use it? (dilution rate, etc)


Final question : Would soaking the probe in Star San sanitizer do the job?
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: linuxboy on November 11, 2013, 06:05:07 AM
Quote
isn't the probe too sensitive?
Kind of. It's sensitive to ion differentials. So if you store in deionized or distilled water, it will pull KCl (most probes) or whatever the solution is through. Otherwise, nah.

Quote
Seems to me it takes care of steps 1 & 2 easily. Pretty cheap too!
Yep, but remember this is for stubborn protein deposits. You can also use a bleach solution and a 10 min soak. oh and no, te renu liquid is not foil oil removal. that takes a degreaser.

Quote
Is there a household product I can use for this? and how would I use it? (dilution rate, etc)
Yes, salt replacer is KCl. But it's super cheap to buy online if you can't find. like $4/lb cheap. Make saturated solution. Not sure what more you need. Saturated solution is made when no more salt dissolves. Heat the water up so it's faster.  Or if you want calculate the molarity.

Or just buy commercial probe cleaner for $10 and soak in that for half a day. It usually does the job, although not quite as thorough as a full reconditioning process.

Also check the probe temp tolerances for the KCl soak. some should not go beyond 50-60C.
Title: Re: pH Meters & Dairy - Measuring, Calibration, & Maintenance
Post by: Spoons on November 11, 2013, 07:35:32 AM
Thanks, Mr. White!