I should have added...to be clear...that we don't pour off the 0'C water, we immerse the probe in the slurry.
In pipfruit stores, if the fruit freezes, the cellular structure is damaged, so the produce is held just above freezing. Some stores (notably large controlled atmosphere sites) have literally hundreds of temp probes for control and monitoring. Zero point calibration of these is checked annually using the above method.
A 6mm SS probe takes approx 2 minutes to stabilise once immersed.