Abstract: A device and a method for mixing and heat treating a liquid product, in particular a beverage, and having a first supply pipe for providing a product concentrate and a second supply pipe for providing an aqueous dilution liquid for diluting the product concentrate, as well as a first steam injector provided at the first supply pipe to introduce a first steam quantity flow into the product concentrate, and a second steam injector provided at the second supply pipe to introduce a second steam quantity flow into the dilution liquid. The product concentrate and the dilution liquid can be simultaneously heat treated and diluted, and the heat supply can be interrupted with an only slight delay in case of a production interruption to prevent overheating of the product.