Sometimes when I make pesto the basil oxidizes and the whole thing turns a really ugly dark brown/green. I wonder if it's because my food processor blade needs to be sharpened? I made it in my blender and it came out fine. Thoughts?
Basil tends to oxidize if it's over-pureed. The food processor does this more quickly than the blender. I usually make pesto in my blender to avoid oxidation.
You can blanch and dry your basil leaves before processing. Your pesto will stay a bright, lovely green.
I read recently (don't recall where) that it's the water on the basil leaves that is the culprit, and so I made certain that the leaves were totally dry prior to making my next batch of pesto in the food processor. It worked - bright green pesto!
You can pour a little olive oil over your pesto if storing in a plastic tub.