I would say a food safe oil, such as a good mineral oil or pure linseed oil, applied boiling hot to the wood (not the linseed oil with dryers added)
I learned in Switzerland about a different way to seal food use wood, soap.
They use a food safe, fat-based lye soap called in German Schmierseife. It works pretty good actually, and looks like oil.
Olive oil can turn rancid.