Sensory characteristics of food products are essential for consumers. It is a challenge for firms to maintain these characteristics constant, with as few variations in quality as possible. The control of quality properties and in particular sensory ones can be carried out using reliable process control strategies. Nevertheless, classical control approaches can only rarely be used in food processes. The scarcity of suitable on-line sensors is closely related to the variability of the raw material, to the complexity of the biological phenomena during processing and to the severe constraints sensors must satisfy , such as hygiene, high humidity, and son on. As a consequenc, some food product properties are very difficult to quantify during food manufacture (Pérez-Correa and Zaror 1993). Various directions have been explored to overcome this problem. The aim of this paper ist to describe the principles of the sensory indicators method. The two stages, formal description and transmission are presented respectively in Part 3 and 4. To illustrate, the results obtained for three applications are presented: the dry sausage fermentation stage, the meat batter chopping and the cheese ripening.