Perhaps the grader itself is not the actual CCP?
I used to work for a spice/seed cleaning company and we used various pieces of equipment as part of the processing line to remove stems, stones, foreign matter etc. None of them, with the execption of the metal detector was a CCP, the CCP was monitoring the quality of the product itself, with regular inspections that were documented, and CAs recorded if required.
No auditor ever had an issue with this. Critical limits were such things as <.0.1% by weight Foreign matter, particle size, bulk density, etc dependant upon the relevant specification. Usually performed at start up until the process was delivering in spec product, then about every 2 hours or when we changed prodcuts or batch. Once the line is running properly it did not vary, i suspect your potato grader would be similar. What can change once it is set up correctly?
Perhaps you could use a similar approach.
Also perhaps you should look at having somebody ( needs to be somebody other than the person who performed the checks and has the authority or knowledge on what to do if the records indicate out of control/limit)) sign off the docs every day prior to filing, so CCP monitored, recorded, verified and filed, with no need to review thenm again unless part of another audit or if there is an issue to investigate.
Paul.
