Testing pH

vilor
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Post by vilor » Wed Feb 08, 2017 04:01

I meant measuring Ph by titration, not TA.
This link gives general idea.
http://www.chemguide.co.uk/physical/aci ... urves.html

I have downloaded a lot of literature, most in Russian (in Russia access to Ph meters is limited).
I never saved links and now trying to search through my files.
It's a mess. I will try my best. I closed the project a long time ago. Gave up.
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redzed
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Post by redzed » Thu Feb 09, 2017 02:47

vilor wrote:I meant measuring Ph by titration, not TA.
Well the simple and correct answer here is you can't. Titration is a method to test the titratable acidity in a solution, while pH is an expression of measurement of the concentration of hydrogen ions in a solution. I'm far from being a chemist, but I understand that the two are not the same. As I already pointed out, titratable acidity will give you the amount of acid in a solution, while the pH expresses the strength of the acid.

Here is a quote from the University of Guelph, regarding testing acid content in cheese. I believe this explanation can also be applied to meat. https://www.uoguelph.ca/foodscience/book-page/ph-0

TA and pH are both measures of acidity but, for most purposes, pH is a better process control tool, because the pH probe measures only those H+ which are free in solution and undissociated with salts or proteins. This is important because it is free H+ which modifies protein functionality and contributes sour taste. It is also the pH rather than titratable acidity which is the best indicator of the preservation and safety effects of acidity. It must be emphasized, that the most important factor available to the cheese maker to control spoilage and pathogenic organisms is pH control. The pH history during and after cheese manufacture is the most important trouble shooting information. Cheese moisture, mineral content, texture and flavour are all influenced directly by the activity of free hydrogen ions (i.e. pH).

You can obtain a reasonable pH reading using inexpensive test strips or cough up the money and but a meter. Meters have come down in price and you can probably find one for less than $100 if you order directly from China.
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Post by vilor » Thu Feb 09, 2017 06:23

Thank you very much for detailed reply. Last time I looked at meat probe alone it was $250. I have heard that even if you don't use it, it loose accuracy in year. So, I will live without Ph for now. Thanks again.
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Post by vilor » Thu Feb 09, 2017 06:35

Also found this, look at the graphs, scroll down.

http://www.cider.org.uk/phandacid.htm

The above refers to this

http://cjoliprsf.ca/Documents/Acidity-pH.pdf

Although it is for cider, I was hoping to get this for meat.
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Post by redzed » Thu Feb 09, 2017 15:42

Yes those are good links and contain a lot of what I learned through my wine making club. A number of the guys there are very knowledgeable and have been good mentors.

Here a a couple of inexpensive options of pH meters with the pointed glass probes that I "think" will work in testing meat. pH electrodes do not last forever, I'm on my third one since I bought my meter in 2012. The first one stopped working in under 2 years but I probably was not taking good care of it. I accidentally broke the second one and the third one is working well so far, but I have a spare. This hobby is not that cheap in the end, but better than building birdhouses. :lol:

https://www.aliexpress.com/item/PH-03-I ... a5b5dd873d

https://www.aliexpress.com/item/PH-9810 ... e207&tpp=1
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Post by vilor » Thu Feb 09, 2017 18:20

These are actually cheap. I have always suspected that not meat specific probe wouldn't give accurate reading.

This relates to it https://www.ncbi.nlm.nih.gov/pubmed/22055566



Have YOU used the one you recommend and have you been able to track Ph decrease with 5 hour increments?
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Post by Bob K » Thu Feb 09, 2017 18:35

I use a Milwaukee with a non meat probe. You just need to make a slurry.
Lots in info here: http://www.wedlinydomowe.pl/en/viewtopic.php?t=7737

The meat probes however are more convenient and easier to clean.
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Post by vilor » Thu Feb 09, 2017 18:59

I have researched the slurry option before and reject it.
This is why:

1. Lack of standartisation for particle size
2. Inconsistent water amounts used for suspension available through google
3. lack of comparative data (my link in prev post)

It reminded me of my musician friend, who hardly knows how to break an egg. She bought a floor scale and then returned it 3 times, settling on the one which showed the least weight. No wonder, she knows nothing about setting zero.
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Post by Bob K » Thu Feb 09, 2017 21:12

Ok you need to satisfy your own standards. Best of luck.
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Post by vilor » Fri Feb 10, 2017 04:50

If Ph meter is designed for cheese and fluids, knowing how tricky Ph measurement is, it should be reasonable to doubt the accuracy. One can measure engine bore with a brake caliper, but with certain consideration.

I have been considering to buy the cheese Ph meter and compare the readings to the "real" meat unit, but couldn't find anybody around with certified meat Ph meter.

Sorry, if my posts are disturbing, but I do have some qualifications in measurement and am familiar with standards, which are NOT my own.

I greatly appreciate all your advice and all potential future contributions to the topic.
Hopefully, the group will benefit from this information.
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Post by Butterbean » Fri Feb 10, 2017 15:40

As for certification of a meter, I do this each time I calibrate the meter before use in the buffer solutions. I trust the labs who make these solutions know what they are doing.
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Post by vilor » Fri Feb 10, 2017 16:08

I understand. But you are certifying a cheese Ph meter. Unless it says in the manual "to measure meat Ph" we can't assume that the reading represents meat Ph.

There are two ways to proceed.

1. Buy $$$$ meat meter with probe and not to worry
2. Buy cheese meter, soil meter, milk meter cider meter or any other type of equipment for less $$, take a piece of meat (or slurry) and compare the readings to the meat Ph meter (certified)

this is what I meant.
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Post by redzed » Fri Feb 10, 2017 16:24

vilor wrote:Sorry, if my posts are disturbing, but I do have some qualifications in measurement and am familiar with standards, which are NOT my own.
I don't find your posts in any way "disturbing". We all have different ways and personal standards of approaching and understanding technology. Having said that, your questions regarding the suitability of a pH electrode in testing meat when the manufacturer states that it will work in solutions, cheese, semi solid foods and soft soils, should be directed to that manufacturer or a technological expert. Obviously your standards are higher than those of the average forum participant. The members of this forum are hobbyists and small producers who rely on, and for the most part, trust the instruments we use.

There is no merit in continuing this discussion on this forum.
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Post by Butterbean » Fri Feb 10, 2017 16:29

Whether I'm using litmus paper or my meter I normally test the green meat and this will give me the initial pH of the meat and this should/has always fallen within the range of the documented pH range of that particular meat. From there I test the mince after it has fermented - I normally keep some horn scrap in a tupperware container for this. I can also use a little common sense and use my own senses to tell how things are progressing. So if the probe has been calibrated, and the probe gives a reasonable reading of the pH of the green meat why then would I question the accuracy of the post fermentation reading when it is steadily going down not to mention the sensory indicators this process creates?
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Post by vilor » Fri Feb 10, 2017 17:51

This is great to know. Although your test is not ideal, but this is some type of cross validation. Have you used your ph meter within 1 hour postmortem? Does it show 7?
If yes, could you share exact model number for your meter and probe, I will buy it tomorrow.
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