Acidity versus curd?

[Gürkan Yeniçeri]

Thanks Sailor, I will calibrate it with two solutions and have a reading after that. As I usually follow the instructions that came with it (and they are usually either not enough or wrong all together), I was always doing one calibration only.

[linuxboy]

Gurkan, do you have a good cleaning procedure in place to make sure there's no gunk on the junction or bulb?

[Gürkan Yeniçeri]

After every dip into the sample milk, I wash it with soap and rinse it thoroughly. It is the IQ125 from cheesemaking.com.

I calibrated with 7 first and pressed the second calibration button, 10.1 was flashing but it came with 10 reference solution so I used that instead. I took a reading but pH was still high. Do you think the meter is faulty some how?

[linuxboy]

After you calibrate with 7 and put it into 7, does it still read 7? Also, is the 7 buffer clean?

[Sailor Con Queso]

Gurk,

You should always calibrate with the 2 points closest to your working environment. Since the pH on cheese drops during a make, the calibrations should be at 7.0 and 4.0. Calibrating to 10.0 is probably not useful because it won't be accurate on the lower pH readings like 4 or 5. If your meter won't calibrate to 7.0 and 4.0, I would consider getting a better meter.

[zenith1]

I agree- when you run calibrations you have to use calibration solutions of know value and  that are in the range of measurement that you are going to be working. That is true with cheese making also, and that is why you would use two set points at the outside range of what you would expect in the make process.(4&7) To use one point only does not give you a valid curve, anything above or below that point is not known to be valid so you only know that the meter is correct at that one point. In that lab world after a calibration of two,three however number of points you would run a control(or two or three) in the range that you are working and verify that your instrument is indeed calibrated correctly and giving expected values.