This paper presents an information system developed to help the assessment of the microbiological risk in food products. UQS (Unified Querying System) is composed of two distinct bases (a relational database and a conceptual graph knowledge base) which are integrated by means of a uniform querying language. The specificity of the system is that both bases include fuzzy data. Moreover, UQS allows the expression of preferences into the queries, by means of the fuzzy set theory.