In the food industry, information captions are affected by the scarcity of suitable on-line sensors especially with respect to controlling sensory properties. Therefore it is often necessary to rely on human evaluations made close to the line, in order to asses quality characteristics of food products during their manufacture. This paper presents a method to collect and formalise the know-how of skilled operators concerning these evaluations. The classical descriptive sensory method has to be adapted to the at-line measurement constraints. These specificities led us to develop the concept of sensory indicator and establish a new formalisation grid. This grid is composed of seven elements: name, definition, operating conditions, scale, references as scale anchors, a spatial characteristic that takes into account the spatial variability of products, and a temporal characteristic that takes into account changes of the product through time. The method is il-lustrated by industrial applications. The results have shown that it is possible to formalise and transmit knowledge concerning at-line human evaluations of products and use them as input variables in process con-trol models.