Washing and chilling as critical control points in pork slaughter hazard analysis and critical control point (HACCP) systems D.J. Bolton 1 , R.A. Pearce 1 , J.J. Sheridan 1 , I.S. Blair 2 , D.A. McDowell 2 and D. Harrington 3 1 The National Food Centre, Teagasc, Dunsinea, Castleknock, Dublin, Ireland, 2 Food Microbiology Research Group, University of Ulster, Newtownabbey, UK and 3 Head Office, Teagasc, Sandymount, Dublin, Ireland 2001/267: received 29 August 2001, revised 29 November 2001 and accepted 30 November 2001 D.J. BOLTON, R.A. PEARCE, J.J. SHERIDAN, I.S. BLAIR, D.A. MCDOWELL AND D. HARRINGTON. 2002. Aims: The aim of this research was to examine the effects of preslaughter washing, pre-evisceration washing, final carcass washing and chilling on final carcass quality and to evaluate these operations as possible critical control points (CCPs) within a pork slaughter hazard analysis and critical control point (HACCP) system. Methods and Results: This study estimated bacterial numbers (total viable counts) and the incidence of Salmonella at three surface locations (ham, belly and neck) on 60 animals/carcasses processed through a small commercial pork abattoir (80 pigs d )1 ). Significant reductions (P <0®05) in bacterial numbers were noted at some stages of the slaughter/dressing process, i.e. the process of hair removal (scalding–dehairing and singeing) resulted in an approx. 4®5 log 10 cfu cm )2 decrease in bacterial numbers. A significant increase (P <0®05) in bacterial numbers was observed after pre-evisceration washing. Final washing increased the bacterial counts to between 3®6 and 3®8 log 10 cfu cm )2 while chilling effected a small but statistically significant (P <0®05) increase to between 4®5 and 4®7 log 10 cfu cm )2 . The incidence of Salmonella on pigs at the farm was 27%, decreasing to 10% after preslaughter washing. However, stunning and bleeding effected a considerable increase in Salmonella contamination and the incidence after these operations was 50%, which was reduced to 0% during the scalding–dehairing process. Conclusions: Washing the live animals and subsequent carcasses with cold water is not an effective control measure but chilling may be used as a CCP. Significance and Impact of the Study: Recent changes in European Union legislation legally mandate HACCP in pork slaughter plants. This research will provide a sound scientific basis on which to develop and implement effective HACCP in pork abattoirs. INTRODUCTION Pork products may be contaminated with a range of human pathogens, including Salmonella (Berends et al. 1998; Cloak 1999), Campylobacter (Bolton et al. 1982; Epling et al. 1993), Escherichia coli (Doyle and Schoeni 1987; Korsak et al. 1997), Yersinia (Feng and Weagant 1994; Duffy et al. 1999) and Listeria (Sheridan et al. 1994; Borch et al. 1996). With the exception of Listeria, which is more usually an environmental contaminant, many such pathogens enter the slaughter environment on or in live animals. Thus, Salmonella, Campylobacter, E. coli and Yersinia are carried into the plant in the porcine intestinal tract or in faeces adhering to the skin, while Yersinia can also be carried on porcine tongue and tonsils. Thus, most abattoir environ- ments quickly become contaminated (Mafu et al. 1989; Hald et al. 1999). Consequent cross-contamination of the product Correspondence to: D.J. Bolton, The National Food Centre, Teagasc, Dunsinea, Castleknock, Dublin, Ireland (e-mail: dbolton@nfc.teagasc.ie). ª 2002 The Society for Applied Microbiology Journal of Applied Microbiology 2002, 92, 893–902