The use of statistical process control (SPC) to enhance the validation of critical control points (CCPs) in shell egg washing Khongsak Srikaeo a, * , James A. Hourigan b a Food Science and Technology Program, Rajabhat Institute Pibulsongkram, Phitsanulok 65000, Thailand b Centre for Advance Food Research, University of Western Sydney, Hawkesbury Campus, Richmond, NSW 2753, Australia Received 28 May 2001; received in revised form 18 January 2002; accepted 21 January 2002 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 sug- gested 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 pro- ductions. 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. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Validation; Verification; CCP; Shell egg washing; SPC 1.Introduction For many years, food industries, government and regulatory bodies responsible for food safety have recognised hazard analysis and critical control point (HACCP) as a useful tool to achieve food safety control. Recently, there are a number of excellent texts outlining practical approaches to the application of HACCP that are being used as guidelines with the most authoritative being that by the Codex Alimentarius (1997). However, very few adequately address the important issues of validation and verification (Mayes, 1999). The Codex Alimentarius (1997) definition of ‘‘vali- dation’’ and ‘‘verification’’ is; ‘obtaining evidence that the elements of the HACCP plan are effective’ and ‘the application of methods, procedures, tests and other evaluations, in addition to monitoring to determine compliance with the HACCP plan’, respectively. This study provides the example of validation proce- dures for shell egg washing which is normally defined as a CCP in general shell egg washing process. This CCP was validated by compliance of the plant data with related literature and applying the appropriate SPC tools, con- trol charts and capability studies, to evaluate the actual implementation status of designed criteria in such CCP. 2.Washingofshelleggs Countries give a different emphasis to the cleaning of shell eggs, reflecting the continuing debate on its * Corresponding author. Tel.: +66-55-215117; fax: +66-55-215117. E-mail address: khongsak@fstrajabhat.org (K. Srikaeo). 0956-7135/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0956-7135(02)00024-5 Food Control 13 (2002) 263–273 www.elsevier.com/locate/foodcont