Try putting an OPEN container of baking soda in with the pieces for 24 hours. Let us know how it goes.
Also, (this is a little more difficult) I was told to put a piece of newspaper in a refrigerator with a tube of toothpaste spread on the paper (cheapest you can find) that has been turned off and the door closed to get the bad odor out. This works like a charm. The toothpast absorbs the odor.