Control of milk processing based on rapid detection of micro-organisms

To monitor critical control points (CCPs) in the food industry, mainly parameters that can be measured by physical–chemical techniques are applied. In this study, various microbiological methods were used to monitor the development of micro-organisms during thermisation and pasteurisation of milk. The results show that of the methods currently available both the Bactoscan analysis and the ATP method offer possibilities for application as an `emergency brakeʹ. The main problem is the sensitivity of the techniques. Levels of 104–105 micro-organisms per ml can be measured, but this is not sufficient to adjust a production process. Techniques based on particle size (distribution), spectroscopy and impedance were not able to differentiate between milk samples containing low levels of micro-organisms and highly contaminated milk. In addition, detection of metabolites produced by micro-organisms offers no alternative; high concentrations of bacteria are already present at the moment any signal can be measured. Therefore, more research is necessary before successful implementation of in-process applications can be guaranteed.