280 Chapter 14
steam (minimum 82 ° C) treatment of car-
casses followed by vacuuming has been
approved for fecal decontamination, if con-
tamination is no more than one inch. This
process can achieve 3.3 log 10 CFU/cm^2 reduc-
tion in total bacterial counts (initial
6.4 log 10 CFU/cm^2 ) and 5.5 log 10 CFU/cm^2
reduction in E. coli O157:H7 counts (initial
7.6 log 10 CFU/cm^2 ) (USDA - FSIS 1996 ).
Moreover, additional testing showed that this
technology was more effective than conve-
nient knife - trimming by 0.5 log 10 CFU/cm^2.
Others have found that a novel vacuum -
steam - vacuum cycle treatment reduces
microbial counts on smaller animal carcasses
such as fi sh (Kozempel et al. 2001 ).
Skinned carcasses can be rinsed with
aqueous solutions of food - grade organic
acids (1.5 to 2.5%), such as acetic, lactic, or
citric acid (USDA - FSIS 1996 ). Snijders et al.
(1985) showed that lactic acid treatment,
when applied to a hot carcass surface, reduced
aerobic plate count by 1.5 log 10 CFU/cm^2.
Goddard et al. (1996) showed that beef loins
treated with lactic and acetic acids had no
difference in color or odor compared to
untreated samples. A potential concern of
acid application is the possibility of patho-
gens adapting to an acidic environment and
eventually surviving in the meat - processing
environment or human gastrointestinal tract
(Samelis et al. 2002 ; Yuk and Marshall 2004,
2005 ). Other approved antimicrobial rinses
include trisodium phosphate (8% to 12%,
32 ° C to 43 ° C) and hot water/steam (min
74 ° C for more than 10 seconds).
Naidu (2002) utilized activated lactoferrin
(a natural iron - binding protein) as a spray
treatment of carcasses. The authors claimed
activity not only against bacterial pathogens,
but also against meat spoilers such as
Pseudomonas spp. and Klebsiella spp.
Several researchers (Kim and Slavik 1996 ;
Cutter et al. 2000 ; Bosilevac et al. 2004a )
demonstrated the effectiveness of cetylpyri-
dinium chloride treatment of poultry and beef
to reduce pathogens and aerobic plate counts.a heating chamber. A radiofrequency oven is
equipped with a generator coupled with a pair
of electrodes and is known as an RF applica-
tor. According to Murano (2003) , micro-
waves can penetrate to a depth of 5 to 7 cm,
which results in faster cooking and fewer
nutrient changes compared with conventional
ovens. Meat spoilage is prevented by simple
cooking (thermal inactivation of spoilage
microorganisms). The alternative nonthermal
effects of microwaves have not been con-
fi rmed (Aymerich et al. 2008 ). For example,
Yilmaz et al. (2005) showed 2 log 10 CFU/g
reductions in total microbial fl ora after micro-
waving meat balls at 2,450 MHz frequency,
in an 800 W oven, for 300 seconds. The major
technical drawback of high - frequency heating
is nonuniform heating. Aymerich et al. (2008)
noted that radiofrequency heating and micro-
waves tend to create cold and hot spots within
meat products due to differences in geometry,
fat distribution, and dielectric properties.
Another drawback is the high cost of equip-
ment and maintenance.
Ohmic heating involves heating foods
between two electrodes by passing electrical
current through the product. The heating rate
is directly proportional to the electrical
current and electrical conductivity of the
food product. According to Piette et al.
(2004) , ohmic heating is currently success-
fully applied to liquid products, with indus-
trial usage for solid meat products yet to
come. The main disadvantage of ohmic
heating is the signifi cant energy cost with
recommended density of treatment intensity
of 4,000 A/m^2 (Hugas et al. 2002 )
Novel Carcass Decontamination
Techniques
Several post - harvest decontamination tech-
niques have been authorized by USDA - FSIS
to reinforce zero fecal contamination, as well
as to extend shelf life, improve microbiologi-
cal quality, and remove pathogens from car-
casses (USDA - FSIS 1996 ). Hot water and/or