If you are afraid to wash them in your washing machine, I would soak them in the bathtub and dry on the line. there are some things that you can buy to soak in that will remove discoloration. I can only remember the name of one--Grandma's secret spot remover is one, but not good for soaking only spot treatments. The other I bought at my LQS and soaked old handmade lace that my Grandmother made that was very grey--It whitened the lace right up--I was amazed. OxyClean is wonderful to remove stains.
Sue