Data verification

Hi to all!
I have been asked to make a PLC program for the food industry. As I have no experience in this section of industry I would appreciate any hints about the requirements for data verfication.In order to make it more clear, what I need, is hints on how do you verify that data/measurements are correct, how do you protect malicious changing of these data e.t.c. I am mostly interested in the European requirements but any hints will be appreciated

Regards
George

As someone who has had to do battle with CFR 21 part 11 (Pharmaceutical industry) - Use a chart recorder.