In the food industry, controlling sensory properties on the manufacturing line represents a key issue for companies, because sensory properties influence consumer choice and preference. Pertinent control of a sensory property depends on the reliability of the measurements of the sensory variables involved in how it is perceived. The browning variable is an important sensory variable assessed by an operator to control the visual quality of browned products. In this paper, we propose a diagnosis model that relies on the fuzzy symbolic approach to ensure reliable measurement of the browning variable. The browning variable is broken down into descriptive variables, which are formalized by sensory indicators. These variables are assessed by the operators with repeatability indexes higher than 90%. The diagnosis model was validated on a database with a percentage of compatibility of 92% at a sensitivity level of half a symbol.