Before moving to NC this summer, I guided bear hunters in the great state of Maine. I always used donuts,breads,oats,grease and beaver meat. I feel you give the bears a variety and they will return to the bait site daily for the free food. Like what was stated previous, pour grease around the area and the bears will leave a scent trail exiting the site which in turn will bring more bears to your area. Also, use a backer of some sort so the bear has to present itself in order to get to the feed. Nothing worse then feeding a few bears that can sit in brush and feed freely.
Good Luck, John