Fluid food products, in the agri-food industry, are commonly subject to thermal treatments to ensure their safety and quality characteristics. Therefore, these treatments must be accurately selected and monitored to avoid over-processing, as consumer safety and product acceptability must be preserved. In this work, thermal processing is predicted locally by modeling and visualizing selected bio-indicators (bacteria and vitamins). A sample sterilization of citrus juice is scrutinized through a multidimensional numerical analysis for fluid flow, heat transfer and bio-indicator kinetics and transport, by including proper biochemical evolutive notations. Direct steam injection is used as the thermal carrier, so complete two-phase notations are included. Good agreement has been reached, with the available experimental benchmark data. Process performance is evaluated by inferring on survived microbial and native vitamin patterns, and the relative importance of kinetics over macroscopic transport is discussed.