the invention is a process for preparing a yoghurt with a desired gel strength . it is based on the unexpected observation that gel strength can be varied by varying the ph to an optimum at a given weight ratio of casein to whey protein . whey protein is added to a milk and the casein : whey protein weight ratio is calculated . the optimum ph for that ratio is determined . the milk solution is then adjusted to that ph , heated to denature the whey protein and formed into yoghurt by known methods . the gel strength of the resulting yoghurt is determined by the optimum ph used in the heating step .