I using 17-55mm for food photos and i'm loving it :bsmilie:
As for 50mm for cropped sensor, I find it too tight for me. Prefer a zoom lens as I took most of the photo in restaurants so I don't have to stand up and move around the table looking werid
Most pro do used marco lens for food photography
And for Canon the focal length avaliable for macro is 50mm, 60mm, 90mm, 100mm and 180mm which I do feel is too tight for food photography on a crop sensor.