Meat Decontamination 55Chemical Decontamination
In addition to the aforementioned physical
decontamination methods, interventions
involving chemical agents have also been
recommended and used on carcasses (Fig.
3.1 ) (Smulders and Greer 1998 ). A signifi -
cant amount of research has been undertaken
into the chemical decontamination of beef
carcasses over the last 30 years, in order to
reduce total bacterial numbers and presence
of pathogens. Nowadays, chemical interven-
tions are applied as components of multiple
sequential interventions, including knife -
trimming, steam - vacuuming, and thermal
(hot - water or steam) treatments (Dickson and
Anderson 1991 ; Hardin et al. 1995 ; Gorman
et al. 1997 ; Castillo et al. 1998c, 1999a, b,
2001a, b, 2003 ; Stopforth et al. 2004, 2005,
2007 ; Geornaras and Sofos 2005 ; Table
3.1 ). Chemicals used or proposed for use in
carcass decontamination include organic
acids, acidic calcium sulfate, acidifi ed sodium
chlorite, a peroxyacetic acid - based solution,
potassium hydroxide, and other commer-
cially available mixtures of approved chemi-
cals (USDA - FSIS 2008c ). Chemical rinses
may be applied pre - evisceration, or post -
evisceration before chilling, as well as during
spray - chilling and after chilling as carcasses
are removed to be fabricated (Fig. 3.1 ).Organic Acids
Lactic and acetic acid have been widely used
at concentrations of up to 5% and have
resulted in 2.2 – 5, 1.4 – 4.9, 0.40 – 1.6, 3.6 – 4.7,
1.6 – 4.9 and 1.5 – > 3.6 log 10 CFU/cm^2 reduc-
tions of Salmonella , E. coli O157:H7, L.
monocytogenes, Yersinia enterocolitica ,
Enterobacteriaceae , and APC, respectively,
on beef, pig, lamb, or poultry carcass
tissues (Anderson et al. 1988 ; Gorman et al.
1995b, 1997 ; Hardin et al. 1995 ; Goddard
et al. 1996 ; Podolac et al. 1996 ; Kochevar
et al. 1997b ; Castillo et al. 1998c, 2001a, b ;
van Netten et al. 1997 ; Cutter 1999 ;(15 – 82 ° C for 10 s; Dorsa et al. 1996b ).
Nonetheless, combination of steam pasteuri-
zation with knife - trimming or steam - vacu-
uming may increase microbial reductions
(Phebus et al. 1997 ).
Post - evisceration steam pasteurization of
carcasses in a beef slaughtering plant caused
decreases in the percentage of positive
carcass samples for E. coli , coliforms, and
Enterobacteriaceae , as well as Salmonella
from 16.4, 37.9, 46.4, and 0.7%, to 0, 1.4,
2.9, and 0%, respectively (Nutsch et al.
1997 ). However, concerns have been
expressed as to whether steam - pasteurized
carcasses become more susceptible to bacte-
rial attachment in case of recontamination
(Warriner et al. 2001 ). Reported reductions
for E. coli O157:H7, S. Typhimurium, and L.
monocytogenes, achieved by post - eviscera-
tion steam pasteurization (105 ° C, 6 – 15 s),
range from 3.4 to 3.7 log 10 CFU/cm^2 (Phebus
et al. 1997 ). The respective reductions for
APC, TCC, and E. coli are 2 to 3 log 10 CFU/
cm^2 (Gill and Bryant 1997b ; Nutsch et al.
1997 ). Furthermore, ultra - high temperature
steam (140 ° C) for 5 seconds yielded 4 log 10
CFU/cm^2 reductions of L. innocua on the
surface of poultry carcasses (Morgan et al.
1996 ). In addition to steam - fl ushed cham-
bers, Retzlaff et al. (2004) proposed the use
of a static steam system, applying a constant
fl ow of steam at temperatures of 82.2 – 98.9 ° C
for 6 – 15 seconds. Steam of 98.9 ° C for 9
seconds afforded the highest reductions of E.
coli O157:H7 (4.1 log 10 CFU/cm^2 ), without
negatively affecting color and texture of beef
(Retzlaff et al. 2004 ).
Overall, steam pasteurization requires a
major capital investment, but it can be an
additional intervention that can cause further
reductions to those achieved by knife - trim-
ming, washing, and/or chemical rinses before
chilling (Dorsa et al. 1996b ; Gill and Bryant
1997b ; Phebus et al. 1997 ; Gill and Landers
2003b ). Therefore, in the United States,
steam pasteurization has been successfully
used in beef slaughter.