Several studies on animal feed heat treatments have revealed that Salmonella bacteria in such products can be destroyed by applying a time/temperature scale (moisture content).
Sector industrials generally apply these treatments in the form of continuous processes. Their effectiveness depends mainly on the control of time and temperature factors; the time factor is the most difficult to measure and control, due to spread in residence time distribution patterns.
When a product is treated in a continuous system (or reactor-mixer), particles do not all pass through the system at the same speed resulting in differing treatment times; this is the phenomenon responsible for residence time distribution spread or RTD.
This phenomenon is of major importance in a thermal destruction process targeting microorganisms as the particles with the shortest residence times may leave the facility before decontamination is complete.
It is therefore essential to have accurate data on residence time distribution in order to be able to qualify the length of treatment times in a continuous process.
Measuring particle residence times in the process and grouping this data by category makes it possible to:
• plot the distribution of residence time categories on a graph,
• use parameters to describe particle