A high-precision temperature information is required to follow the recipe in automatic cooking processes of heterogeneous liquids. Therefore, measurement equipment plays a crucial role in appliances developed for automatic cooking processes. However, it is difficult to obtain the temperature information in such appliances since the sensors cannot be located inside the heterogeneous liquid and the diffusion model is not precise in general. In this manner, a method is proposed to estimate the temperature of the heterogeneous mixture during the cooking process. This is achieved by the utilization of only one temperature sensor located at the outside wall of the cooking chamber in a commercial Turkish coffee machine. The temperature of this point with the sensor is considered as the output while the mixture temperature is assumed as an internal state, then a model is generated based on collected data in a special experimental setup. Experimental results show that the Turkish coffee can be cooked with required taste and consistency by the application of the proposed method.