The Model IQ240 is equipped with 0.001 resolution. This research grade resolution is not required in most dairy applications. Be sure not to use 0.001 resolution or unnecessary time will be required to reach an endpoint reading. Rinse probe with a jet of distilled or dionized water from a right angle squirt bottle. Point the stream right at the sensor to remove any of the sample left on.
Protein is the biggest single problem in pH testing in dairy applications.
In glass electrodes it gets in the glass and is very difficult to remove. Traditional glass electrode manufacturers recommend HCl acid dips or pepsin solutions. In the case of silicon chip sensors, the proteins still attach to the sensor, but the sensor is non-porous so proteins can be removed without degradation of the sensor. Rinse well, then recalibrate. It is not necessary to use the bleach cleaning solution unless response time slows.