The past tense of Sterilize is sterilized.
verb. ['ˈstɛrəˌlaɪz'] make free from bacteria.
1. Verb, base form Clean and sterilize the container if you have used it before. 2. Verb, non-3rd person singular present Always sterilize pruning equipment before and after using it by wiping it with a cloth soaked in rubbing alcohol.
verb. ['ˈstɛrəˌlaɪz'] make infertile.