Applying statistical process control to monitor and evaluate the hazard analysis critical control point hygiene data

Abstract Rapid hygiene testing systems employing the ATP Bioluminescence Technique are widely used to assess the hygiene status of various Control Points (CPs) in any Hazard Analysis Critical Control Point (HACCP) system. The measurement in Relative Light Units (RLU) is then used to give a Pass/Fail status to the CP tested. This paper highlights the potential benefits of applying appropriate Statistical Process Control (SPC) tools like Cusum Charts and Individuals Charts to the RLU data. In a typical dairy operation, RLU data collected over a period of three months from a CP of a milk filling machine were analysed in retrospect. The analysis showed that the Cusum and Individuals Charts established a proper trend analysis of the RLU data. Advance warning signs signifying potential out of control (Fail) CP status were clearly shown on the charts. The findings highlight the fact that by employing SPC, it is possible to prevent CPs from failing the hygiene test. Furthermore, if the SPC technique of identifying assignable and unassignable causes of failure was adopted, the total number of failed CPs should decrease. This would, in the long run, lead to more effective hygiene management and more efficient production.