All yogurts, including the base for frozen yogurt, are made using the same base bacteria with additions for bio, propionic, etc. What was the frozen yogurt made from? If the base has been UHT’d, then all the yogurt organisms have been killed prior to the making of the frozen yogurt. It is possible to buy yogurts where the product has been sterilised, and the yogurt bacteria killed. If the yogurt is in the chiller cabinet, then the yogurt bacteria are live. If the yogurt is not in the chiller cabinet, then the likelihood is the product is shelf stable, and sterile, and the organisms dead. These types are not made in the UK, but imported and are called pasteurised yogurts.