I can understand how to measure pH in whey, but what about curds or cheese? Do you make a 1:1 aqueous extract or just poke the probe into the solid material to get direct contact?
Two considerations here. One: scientific accuracy, two: practicality. To measure pH of a made curd or cheese, the lab process is to puree it with an emulsifier additive and distilled water. This puts everything into solution, giving a fairly accurate pH measurement. For normal home purposed, this is not practical. The general consensus here during our last big "where to measure" discussion is to measure the whey at the closest point to the curd. Meaning, you press into a piece of curd you have reserved so a little of the whey comes out, and the pH meter measures whey. If you measure the leftover whey after you drain it, or just stick it in the pot if you are pressing under the whey, it is not as accurate because the curd and whey start to diverge enough to be dissimilar at about the point of whey drain, which is ~6.2.
Of course, if you're measuring a finished cheese, you'd need to puree it because there's no whey left that seeps out.
Quote from: linuxboy on January 15, 2010, 04:54:49 PM
Two considerations here. One: scientific accuracy, two: practicality. To measure pH of a made curd or cheese, the lab process is to puree it with an emulsifier additive and distilled water. This puts everything into solution, giving a fairly accurate pH measurement. For normal home purposed, this is not practical. The general consensus here during our last big "where to measure" discussion is to measure the whey at the closest point to the curd. Meaning, you press into a piece of curd you have reserved so a little of the whey comes out, and the pH meter measures whey. If you measure the leftover whey after you drain it, or just stick it in the pot if you are pressing under the whey, it is not as accurate because the curd and whey start to diverge enough to be dissimilar at about the point of whey drain, which is ~6.2.
Of course, if you're measuring a finished cheese, you'd need to puree it because there's no whey left that seeps out.
With some PH meters you can stick it directly into the solids.
The ExStick ones that everybody has here does that.
What is different about the Extech? It looked like it was just a calomel electrode like any other. I debated getting it but went with the economical one to get me started.
Lennie, nothing special about it. You can use any electrode, so long as the curd will let go of a little whey. That's basically all cheeses, because even parm or similar hard cheeses will release a little whey when you press. You just need to get enough on the membrane to activate the potential so voltage can be measured.