The use of statistical process control (SPC) to enhance the validation of critical control points (CCPs) in shell egg washing

Abstract

This study illustrates the application of validation principles to evaluate the scientific and technical content of the critical control point (CCP) in a hazard analysis and critical control point (HACCP) system. A commercial shell egg washing step was selected as a demonstrated process. Validation procedures involved in compliance of the obtained commercially operated data with the related literature and applying the appropriate statistical process control (SPC) tools. The results showed that the critical limits of all control measures defined for this CCP in the observed plant, pH of wash water (11–13), temperature of wash water (32–44 °C), temperature of rinse water (41–49 °C) and chlorine level (100–200 ppm) are in accordance with those generally recommended by many related literature to ensure safe food production. Recommendations suggested by related literature were that pH of wash water should be 10–11, however, >11 was tolerable, temperature of wash water should be at least 12 °C higher than eggs and not in excess of 50 °C, temperature of rinse water should be slightly higher (3–4 °C) than wash water temperature and chlorine (sanitiser) level should be between 100 and 200 ppm. Hence, this CCP was judged to be valid. The evaluation by applying the trial control charts to all collected data over the period showed that the process was not in control in all control measures (presence of tests of assignable causes). The process variability (control limit) was assumed as a “current actual performance” and compared with the recommendations. Most control measures are satisfactory in terms of safe food productions. Some special considerations were made on particular control measures such as wash water temperature and chlorine level. The process capability studies were conducted for treated data and the results showed that all control measures are capable to the designed critical limits except chlorine level whose process spread (6 sigmas) falls outside the width of critical limits.