There is currently no known safe treatment to make silicone stain proof or stain resistant. Since we use the highest grade silicone for our goodies, and because silicone is a naturally porous material, the natural dyes found in highly pigmented foods like beets and sweet potatoes may sometimes cause discoloration. A similar situation would be tomato sauce staining your Tupperware. Because your baby’s safety is our #1 priority, we choose not to use any chemical coating which would seal our silicone products from being stained, as we don’t want chemicals to come in contact with baby food and little mouths :) To help avoid staining, we recommend washing immediately after each use. For more stubborn stains, we recommend soaking the item in a solution of baking soda + water or white vinegar + water for several hours. If you are still unable to lighten the stains, try soaking in the solution at full strength (just white vinegar or just baking soda) without diluting with water. Laying the item to dry in the sunlight is another natural remedy that has proven effective!