My boyfriend cannot eat yoghurt because the bacteria normally used upsets his stomach. He once was given a sample of yoghurt ice cream made using a different strain of bacteria, and this was ok – but he cannot, unfortunately, remember the name of the bacterium used. Do you know what this could have been?

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.