Can Schedule 40 PVC refer to non-Rigid and Rigid or uPVC pipe (for food safety)?
Schedule 40 is a thickness standard.
Schedule 40 is thinner than schedule 80 and they are considered rigid with pipe.
When you are discussing food grade it actually can be affected by the type of food. I know in some cases plastics were not allowed only stainless (years ago there may be modern plastics that can handle high acid then base ph levels other than stainless )
You would not want to use schedule 40 conduit or soil pipe for example.
Knowing the type needed would help. Provide a better answer but schedule 40 is basically a pipe thickness.