pH Equipment? Why? For what?

[Likesspace]

Wayne, you did. I'm dense sometimes. Thanks!
The page is bookmarked. I'll order some of this tomorrow.
Thanks again.

Dave

[wharris]

Nice setup Wayne.  Is that a stirring hotplate in the background?  With a titrator over it?

Yes, I have a couple of ring stands that use for TA analysis of my wine. I'm currently working on creating an AO apparatus for determining Free S02, and a still for Alcohol determination.

Good idea on marking wash bottles. Thanks.

[Michael_A]

Interesting.  Those sound like some fairly demanding procedures.  Is that a still for determining how the alcohol tastes?

Michael

[wharris]

The Still is for determining Alcohol By Volume. (afftects taste and shelf life)

[Michael_A]

I found this in a paper that is in the library on this site.

Eleven recommendations for more accurate pH testing
1. Keep the reference electrode chamber filled to the fill port with electrolyte solution. This creates a
slight hydrostatic pressure that helps the solution flow through the junction.
2. Any crystals in the reference component of a combination electrode can cause problems by
clogging the junction. Remove crystals by flushing with warm deionized water.
3. Keep calibration buffers in separate, closed containers at room temperature, and replace them
after a few days of use. Keep reserve supplies refrigerated in tightly closed bottles marked with the
dates they were first opened. Once opened, buffers should be used within two months and must be
discarded if any cloudiness or specks appear in the liquid.
4. After setting 4 and 7 calibration points to bracket the anticipated pH range of the cheese samples,
use an intermediate buffer such as pH 5 to check the accuracy of the calibration. A displayed value
that deviates more than ± .03 pH units from 5 indicates an inaccurate meter setting for the pH 4 or
pH 7 buffer.
5. Before using the absolute millivolt mode of a pH meter to check electrode slope, set the meter to
zero millivolts using a shorting strap or plug.
6. A responsive electrode normally has a slope of ± 50-60 millivolts per pH unit. Given a value for
pH 7 buffer of zero millivolts (neutral — neither acid nor alkaline), the electrode in the example
should have produced a reading of at least 150 millivolts while in the pH 4 buffer.
7. Sample and buffer temperatures should be the same. If the temperature difference between the
buffers and sample is excessive (more than 5°C), recalibrate the meter using the temperature of the
sample as a basis.
8. Blend cheese samples, especially those from recent production, before measuring pH. The probe
will then contact the sample in a location that represents its average composition.
9. Even slow drifting of displayed pH values after 10 seconds of contact with the sample indicates a
problem with the electrode. In the example, the junction of the electrode is probably clogged. While
new meters with automatic endpoint recognition are convenient, they may conceal drifting by
artificially creating a stable reading before the “best” value has been reached.
10. Use a fat solvent followed by an acidic solution to dissolve the film of fat, protein, and minerals
that accumulates on the electrode tip when cheese and other milk products are tested. While a squirt
bottle is good for removing cheese particles, it is ineffective for removing this film.
11. Avoid rubbing the glass or plastic electrode body while drying it, as this may create a static
charge. Simply blotting the end of the probe with a tissue or cloth will remove droplets without
affecting the electrode’s sensitivity.

M

[Boofer]

Michael - Excellent and refreshingly informative posts! You've undoubtedly answered a lot of unposed questions for a lot of readers here. Thank you for that.

Have you joined the cheese making foray?

Wayne - Apparently that rinse is currently not available through the Amazon link. Perhaps it is somewhere else. I haven't looked.

-Boofer-

[Brie]

I've been using alcohol prep pads to sterilize thermometer (and then let dry). What say you about that Michael?

[Michael_A]

Hi Boofer,

Thanks.  I'm still in the equipment assembling stage for cheesemaking, though I will hopefully be there in a few days.  I did make some cultured butter last night, does that count?

Brie,

Alcohol won't sterilize, but it certainly will disinfect.  Either ethyl or isopropyl alcohols should work ok.  And my guess is that they are all that is needed.

I am pasting a piece below that seems pretty well informed and explains further.

"True sterilization with alcohol is _NOT_ effective.  There is a big
difference between sterilization vs. sanitization vs. disinfection. The
difference from a 12 log reduction in count to a 2 log reduction,
1,000,000,000,000 to 100.  Each has its own requirements.
Which do you really have to do?  This depends on where the electrodes will
be going.  If they are going into a human (brain electrodes),  you need
de-pyrogenation (anti-endotoxin) as well as sterility  by overkill method
or "F sub-o"  (12 log reduction of _Clostridium botulinum_ or 6 logs of
_Bacillus stearothermophilus_ spores).

Alcohol only kills gram positive coccus well e.g. _Staphylococcus aureus_.
 BUT, not G+ rods (_Bacillus_, _Clostridium_) i.e. not endospores, not
yeast (yeast like to make alcohol and are tolerant of ethanol  but less
tolerant of IPA, about 50 times less tolerant according to my studies),
alcohol will also not mold spores.  Gram negative are usually killed if
not in too high bioburden.  In fact, low bioburnen (<2 logs) is always
advisable.

50-70% IPA is optimum for Gram + coccus.  See also the post by
Andreas.Brune at uni-konstanz.de (Andreas Brune), polio vaccine had a problem
in attennuation for a similar reason (alcohol contant was too high and
protected the viruses).

Do you really need sterilization (unlikely)?     Use heat if possible, dry
heat 200C for 2 hours or steam 15 PSIG for 15 minutes or "F sub-o" = 15
minutes at the coldest spot in the load (not just the chamber) .
Sterilization depends on both time and temperature.   

Fast bunsen burner "flaming" with alcohol will not be hot enough nor long
enough to sterilize, but will probably be all you really need for
sanitization."

A trick I read years ago that gives a very near sterile product without autoclaving is to soak your equipment, jars or spoons or whatever, in water overnight and then bring the water to a boil and boil for 15 minutes or so.   The reason this is effective is that the toughest thing to kill are the spores and the water soak supposedly brings the spores out of their dormant state and therefore makes them suseptible to less extreme treatments than full autoclaving.  I think the soak method would make an alcohol wipe more effective as well. I suppose you could just soak in alcohol for small items though I don't know if that would "sprout" the spores or not. 

This sort of sterility probably isn't necessary for cheese making, but it might be useful if you are trying to propagate some starter bacterial cultures.

Michael

[wharris]

There was another recent thread on sanitation here:
Apologies to those that have already read it.

[Brie]

Thanks, Michael--we use the alcohol prep pads at work to disinfect/steralize our thermometers that we test for all of our food; which is why I assumed they would work for my cheese thermometers. I purchase them at Sam's Club for a reasonable price--sold in a bundle of small packets that I keep on my cheese-making counter.

[Gürkan Yeniçeri]

While we are on the pH equipment discussion, what do you guys/gals think about the miniLab IQ125?

Apparently, the tip is stainless steel, stored dry and does not need maintenance.

[DeejayDebi]

It should save a small fortune on solutions.

[Boofer]

Gurkan - The Hach IQ125 looks to be a better solution than any of the other pH meters with the glass bulb sensor. A little pricier, but probably worth it down the road. I haven't invested in one yet...this may be my answer.

-Boofer-

[linuxboy]

I use a lab base unit and buy the electrodes separately. The dairy residues are not an issue if you clean well. I clean with an enzyme solution that breaks down casein and store the electrode upright in a KCl solution. It's overkill, but I replace electrodes once a year  or every few years, depending on condition.

If your pH meter has the BNC connector, you don't need to buy an entire unit, just the ISFET electrode. But keep in mind that most ISFET electrodes are matched and calibrated to the unit. There are some exceptions... I think Oakton makes it in their Flexiphet line. Pricey, though, might be cheaper to get a whole new set.

The ISFET type electrodes are very well suited to cheesemaking because they're easier to clean and maintain.

[Likesspace]

Gurkan....
I've used Hach products a lot in water treatment and they are a good quality piece of electronic equipment.
I've used their TDS meters and they are both quite accurate and easy to use. I would not be afraid of purchasing a piece of equipment that they sell.
My only suggestions would be to do a google search for sellers of this piece of equipment. You might be able to find it at a lower price than New England Cheese Making Supply.
I could be wrong about that, but it is worth a try.

Dave