Silicone ice trays make extracting ice easy, but over time they can pick up odors from the freezer, which can give ice an off-flavor. Here's a way to remove those odors from the tray.
It’s much easier to pop ice cubes out of a silicone tray than it is from a hard plastic one, but over time this bendable material picks up odors from food and from the freezer, which can permeate the ice with off flavors.
Silicone is relatively permeable to gasses, and molds made from it are notorious for absorbing freezer odors and transferring them to the ice they make. The models in our testing were no exception: When we filled them with coffee and left them in the freezer overnight, the coffee odors lingered and required multiple washes to completely eradicate them. (Most silicone ice trays are dishwasher-safe.) The trays also developed a freezer burn smell—stale, sweet, and musty—after just a week of use.
We were intrigued to read in The New York Times about a method for removing the odors by baking the trays for an hour in a 350-degree oven. (Silicone can withstand temperatures of up to 500 degrees, so there is no risk of the trays melting.) So we put it to the test by filling the molds with a particularly aromatic paste of pureed onions, shallots, garlic, anchovies, and olive oil and refrigerated them overnight. When we emptied the trays and washed them the next morning, all still smelled strongly of the paste. We then baked them in a 350-degree oven for an hour. The trick worked beautifully, eliminating all odors.
We also tried alternative deodorizing methods, such as soaking in a solution of baking soda or vinegar overnight or boiling in water for an hour, none of which removed the smell completely.
Bottom line: Baking silicone in a 350-oven for an hour is a great method for removing even strong odors from ice trays. Just be sure your ice trays are silicone and not rubber, which will melt in a hot oven.