Is milk acidic or basic?

Quote: Originally posted by Neil

If you google "milk pH" you get several thousand results which all conclude the same.

Quote: Originally posted by Formatik

I recently tested the pH of raw egg yolk and found it to be very high, around 8.5. Whereas a sodium bicarbonate solution I made had a pH of about 8.0.

This is very interesting, thanks for your results!

I did buy it new.

It's useful because it has the ability to measure temperatures but, more interestingly, datalog. I can plug it in and let it sit there for 6h plotting a temperature curve to find the melting point of something; e.g. my bottle of acetic acid.

It is not exceptionally difficult to build your own datalogging pH meter with an electronics kit. And have it measure other things.

I didn't want to spend 12 months building mine (because I still can't get to grips with microprocessors) so I paid up the cash instead.

The level of resolution displayed on the screen is excessive. I do not need to know an absolute pH to 0.001 and I seriously doubt the probe and meter are capable of that anyway. That level of resolution is useful, however, to check if a pH is static or still changing.

The meters used to measure pool pH or the pH of hydroponic feed bins are fine for a lot of things. Those are on eBay for a few tens of dollars. But pH paper will work for quick checks and something being electronic does not necessarily mean it is more accurate.

Examples

Analog garden pH probe. $10?


The stoner special. $10-60


Someone better at programming than I, and their DIY pH logger. Very, very versatile (can reprogram it to measure, log and do just about anything) and cheap, but also requires knowledge of digital electronics and programming.


The PicoScope is designed to be a cheap multimeter / scope / datalogger with various inputs. It was originally aimed at schools and hobbyists. It is still quite expensive if all you want to do is check a pH. Few hundred.


Fluke 123 scopemeters will read a whole list of values and datalog, but not designed specifically for pH probes as far as I'm aware. About £1k new.


A black (in this case, grey) box datalogger. Many, many input channels.


Fluke 190, the leviathan of multimeters. Few thousand new.


A prebuilt version of the DIY option with the ability to measure from pH probes, thermocouples and other voltage / current sources. Nice big, colour, touchscreen interface. Datalogging to compact flash cards. 16 channels, up to 40kHz on the digital. Cole Parmer price is about £4k without the VAT I think; short of a lottery win, it'll remain gear porn for the hobbyist. Someone who was good with digital could recreate that for a lot less; at a guess, I expect they could do it for a few hundred. There are many cheap microprocessors and FPGAs that have many input pins, DACs, ADCs and output drivers for colour displays, as well as the ability to quickly add a card slot, USB or wireless interface.


The keys to developing these more expensive instruments, an Altium Nanoboard development kit. The fancy gear is usually something like this reboxed into a prettier housing. This is an example of a board the designer will prototype the device on, then (once it's checked) they'll send it off to have their own compact PCBs made for the production run. 3-4 hundred, endless uses.


[Edited on 9-1-2012 by peach]

Thanks peach. So there is more to it than meets the Ei (Ei is the German word for egg pronounced the same as eye). Ar (little ar) .