72 Chapter 3
(r > 0.99) between hide and pre - evisceration
carcass contamination. Therefore, the estab-
lishments should apply prerequisite pro-
grams, including good manufacturing
practices, sanitation standard operating pro-
cedures (SSOPs), HACCP programs, and
carcass - decontamination interventions, so
that carcasses enter the chillers with reduced
contamination (USDA - FSIS 2002 ). However,
even the best decontamination technologies
require the foundation of a good plant design
and hygienic process control (Sofos et al.
1999a ).Potential Concerns and Risks
Associated with Decontamination
An important concern of organic acid decon-
tamination is the potential for selection of
strains that may be able to adapt and develop
acid resistance. Subsequently, such strains
may colonize equipment surfaces, recontami-
nate carcasses, and resist subsequent decon-
tamination treatments (Samelis and Sofos
2003, 2005 ). Berry and Cutter (2000) showed
that acid - adapted E. coli O157:H7 was more
resistant against acetic acid sprays than non-
adapted cells. Similarly, acid - habituated E.
coli O157:H7 was more resistant to spray -
chilling of beef with chemical solutions than
nonhabituated cells (Stopforth et al. 2004 ).
Furthermore, there is a potential risk for
extended survival of E. coli O157:H7 in envi-
ronmental niches, where acidic decontamina-
tion runoff fl uids are mixed with water,
forming sublethal pH environments (pH 4.5 –
5.0). These environments may allow devel-
opment and maintenance of acid resistance
by E. coli O157:H7 with increased potential
of growth initiation compared to cells that
have not been exposed to such adverse condi-
tions (Samelis et al. 2002, 2004 ; Stopforth et
al. 2007 ; Skandamis et al. 2007, 2009 ). Such
situations may also harden bacterial biofi lms
on equipment surfaces and render them less
sensitive to sanitation agents (Stopforth et al.dry (May through June) season (Sofos et al.
1999b, c, d ). Likewise, total bacteria on lamb
carcasses were lower in the spring than in the
winter (Duffy et al. 2001 ). Elder et al. (2000)
and Arthur et al. (2004) in their survey in four
and two meat processing plants, respectively,
indicated that sanitary procedures and post -
evisceration antimicrobial interventions
could reduce the prevalence of E. coli
O157:H7 on carcasses from 20.1 – 43.4% pre -
evisceration to 0 – 1.8% post - processing.
Similarly, Barkocy - Gallagher et al. (2003)
found that the percentage of positive E. coli
O157:H7 and Salmonella carcass samples
was reduced from 26.7% and 12.7% pre -
evisceration to 1.2% and 0.1%, on dressed
carcasses, respectively; that is after interven-
tions with chemicals and chilling. Finally, a
hot - water (80 ° C) decontamination system,
consisting of a stainless steel spraying cabinet
and a recirculation water system, was effec-
tive in reducing microbial contamination on
carcasses and gained approval by FSIS for
commercial use in beef slaughter (Sofos and
Smith 1998 ). Of the aforementioned in - plant
decontamination interventions, water/steam
pasteurization and spraying with lactic acid
are considerably more effective in reducing
TCC and E. coli than water - washing (Gill
and Landers 2003a ). Furthermore, combina-
tion of lactic acid rinses of carcasses, primal
cuts, and contact surfaces for carcass fabrica-
tion may reduce the numbers of total bacte-
ria, coliforms, and E. coli on carcasses and
the processing environment, thereby improv-
ing the sanitary conditions of the plant (Bacon
et al. 2002a ).
The reduction of E. coli O157:H7 during
the dressing process has been demonstrated
in establishments using the best intervention
strategies and processing techniques. Pre -
harvest strategies that may reduce the preva-
lence in feces, as well as additional measures
to prevent pre - evisceration contamination,
would also markedly improve the microbial
safety of the fi nal product (Elder et al. 2000 ).
Arthur et al. (2004) observed high correlation