Biological sterilization indicator (for wet heat sterilization)

When in use, place it in a small beaker, submerge it in water, sterilize it together with the culture medium, and then place it in a 60 degree oven for cultivation. If it still maintains a purple red color after 48 hours, it proves that the sterilization is effective. If it turns yellow, it proves that the sterilization effect is incomplete.