[Federal Register Volume 60, Number 186 (Tuesday, September 26, 1995)]
[Notices]
[Pages 49553-49564]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-23798]



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 Notices
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  Federal Register / Vol. 60, No. 186 / Tuesday, September 26, 1995 / 
Notices  

[[Page 49553]]


DEPARTMENT OF AGRICULTURE

Food Safety and Inspection Service
[Docket No. 95-025N]


Comparison of Methods for Achieving the Zero Tolerance Standard 
for Fecal, Ingesta, and Milk Contamination of Beef Carcasses: Notice of 
Conference

AGENCY: Food Safety Inspection Service, USDA.

ACTION: Notice.

-----------------------------------------------------------------------

SUMMARY: The Food Safety and Inspection Service (FSIS) will host a 
conference to consider ``Achieving the Zero Tolerance Standard for 
Fecal, Ingesta and Milk Contamination on Beef Carcasses'' on October 23 
and 24, 1995, from 8:30 a.m. to 5 p.m., at the United States Department 
of Agriculture in Washington, DC. The conference will consist of two 
sessions on consecutive days. At the first day's session, participants 
will discuss available scientific and technical data comparing the 
efficacy of the methods for achieving the zero tolerance standard for 
fecal, ingesta, and milk contamination of beef carcasses. Participants 
are invited to make presentations regarding this scientific and 
technical data during this first session. At the second day's session, 
participants will discuss relevant public policy issues, including 
public heath, regulatory, and economic issues.
    The input provided at this conference will be taken into account by 
FSIS in deciding whether to approve any methods in addition to trimming 
for achieving the zero tolerance standard.

ADDRESSES: The conference will be held at the U.S. Department of 
Agriculture, in the back of the South Building Cafeteria, (between the 
2nd and 3rd wings), 14th Street and Independence Avenue, SW., in 
Washington DC. Persons wishing to make presentations at the first 
session of the conference are requested to submit in advance brief 
statements describing the general topics of their presentations. Send 
descriptions to Dr. William James, Director, Slaughter Inspection 
Standards and Procedures Division, FSIS, USDA, Room 202 Cotton Annex, 
300 12th Street, SW., Washington, DC 20250.

FOR FURTHER INFORMATION CONTACT: For further information, contact Dr. 
William James at (202) 720-3219.

SUPPLEMENTARY INFORMATION:

Background

    Effective prevention and removal of fecal, ingesta, and milk 
contamination are among the most important steps companies must take to 
ensure the safety of beef carcasses. Such contamination may harbor E. 
coli 0157:H7, Salmonella, and other enteric pathogenic microorganisms. 
FSIS has a zero tolerance standard for fecal, ingesta, and milk 
contamination of beef carcasses, and is continually seeking the most 
effective, scientifically supportable means of implementing this 
standard.
    The policy of FSIS has been to require the physical removal of all 
feces, ingesta, and milk from beef carcasses by trimming. Before 
February 1993, however, ambient temperature washes were sometimes used 
to remove small flecks of contaminants. Use of ambient temperature 
water washes for this purpose varied across the country and among 
inspection personnel. A distinction between flecks of contamination as 
to their source was not always made, i.e., determinations were not made 
about whether flecks were fecal contamination or rail dust, and, in 
some localities, whether they could be removed by washing.
    In February 1993, after an outbreak of E. coli 0157:H7 in several 
Western States, FSIS reinforced that trimming was to be the only means 
of removing feces, ingesta, and milk contamination from beef carcasses. 
The trim-only policy was based on the judgment that trimming was more 
effective for removing fecal contamination than alternative approaches. 
At the time, there were no scientific data available to the Agency 
comparing the efficacy of trimming and alternative procedures.
    Trimming, if performed properly, is an effective means of 
physically removing from beef carcasses the visible contamination and 
any accompanying microbial contamination. A primary conceptual 
advantage of trimming over ambient temperature washing is that it 
physically removes visibly contaminated tissue (which is more likely to 
be microbiologically contaminated) rather than relying on a wash to 
remove bacteria that, depending on the circumstances, may be firmly 
attached. Also, trimming, when properly performed, is presumed to have 
less potential than ambient temperature washing for spreading 
contamination to other parts of the carcass. On the other hand, if 
trimming is performed incorrectly, it has the potential to cause cross-
contamination as the knife moves from areas contaminated with bacteria 
to newly exposed uncontaminated areas. The effectiveness of trimming 
also depends on the skill of the operator in visually detecting and 
effectively removing contamination, while avoiding further 
contamination by handling the carcass during this process.
    Strict enforcement of the policy requiring that trimming be the 
only means to achieve zero tolerance, following the 1993 E. coli 
0157:H7 outbreak in the Western States, was also based on the Agency's 
need to directly and aggressively remove any potential source of 
pathogenic contamination. FSIS believes that strict enforcement of the 
trim-only approach was appropriate, based on the information available 
at the time.
    Since 1993, numerous other approaches to removing contamination 
have been devised and studied to assess their potential as effective 
alternatives or supplements to carcass trimming to achieve the zero 
tolerance standard. FSIS is now considering whether to permit the use 
of some or all of these alternative approaches. The following material 
reviews current scientific data concerning different approaches to 
achieving the zero tolerance standard for fecal, ingesta, and milk 
contamination on beef carcasses, as they would apply under commercial 
conditions.

Data Review

I. Condition of the Animal on Arrival at the Abattoir

    Any discussion of the sources of pathogen contamination on beef 
carcasses must consider animal husbandry practices and the farm 
environment (Hancock et al., 1994), the possibility of cross-infection 
during transport (Gronstol et al., 1974 a, b), and 

[[Page 49554]]
lairage of the animals before slaughter (Anderson et al., 1961; Grau et 
al., 1968). The practice of regularly cleaning and disinfecting 
transport vehicles and holding facilities reduces the level of 
bacterial contamination in the environment and decreases the risk of 
pathogens being spread between live animals (ICMSF, 1988).
    Soil, feces, and moisture present on the hides and feet/hooves of 
animals entering the slaughterhouse pose a considerable challenge to 
hygienic slaughtering practices (Troeger, 1995). Seasonal and 
geographical factors, together with animal management systems, have a 
tremendous effect on the cleanliness of live animals presented for 
slaughter.
    Although it would be desirable to exclude grossly contaminated 
animals from the slaughterhouse, Mackey and Roberts (1991) concluded 
that such an action could be difficult to rationalize and enforce. Data 
from Finland, however, indicate that exclusion of cattle carrying 
excessive loads of soil and manure can be accomplished, with resulting 
improvements in meat hygiene (Ridell and Korkeala, 1993). As a result 
of imposing regulations requiring that excessively dirty cattle either 
be slaughtered at a ``casualty'' abattoir or processed separately at 
the end of the day using extra care (with any extra costs being 
incurred by the farmer), the number of ``excessively dungy'' animals 
presented at slaughter in Finland has decreased dramatically. Exclusion 
of grossly contaminated cattle is deemed justifiable since such animals 
yield more highly contaminated carcasses, even when slaughtered with 
extreme care and using reduced line speeds. Carcasses from 
``excessively dungy'' cattle had, on average, 5-fold more 
microorganisms per cm\2\ than carcasses from ``control'' cattle despite 
the added precautions.
    Attempts have been made to clean live animals following arrival at 
the slaughterhouse. In general, however, these efforts have not been 
regarded as effective (Empey and Scott, 1939; Roberts, 1980). Though 
Empey and Scott estimated that a cold water wash reduced the bacterial 
levels present on cattle by approximately one-half, such treatments 
have to be applied in such a manner as to restrict later potential 
microbial growth on a wet hide and reduce practical difficulties 
associated with handling wet, slippery hides. These investigators also 
conducted small-scale experiments on the effects of hot water and 
chlorine on microbial loads of hide-on cattle feet (not live animals). 
While chlorine showed some potential, application of hot water was 
thought by the authors to have practical limitations for live animals 
as water temperatures of 75 to 80 deg.C were necessary to achieve 
significant microbial inactivation. Animal welfare concerns and the 
effect on meat and hide quality may complicate or preclude application 
of such antimicrobial treatments to the live animal.

II. Bacterial Contamination During Slaughter

    It is generally agreed that deep muscle tissue of healthy live 
animals is essentially sterile (Gill, 1979, 1982; Zender, et al., 
1958). During slaughter and dressing procedures, the surfaces of 
livestock carcasses become contaminated with microorganisms. The extent 
of this contamination varies depending on the condition of the animal 
upon arrival at the establishment and methods used during slaughter and 
dressing (Roberts, 1980). Contamination of carcasses is undesirable, 
but cannot be completely avoided, even under the most hygienic 
conditions (NRC, 1985; Roberts, 1980; Roberts et al., 1984; Grau, 1987; 
Dixon et al., 1991).
    When meat is produced under hygienic conditions, numbers of 
pathogens contaminating the surface of the carcass are usually small, 
and the micro-flora consists primarily of saprophytic bacteria, such as 
Pseudomonas. Results from beef carcasses sampled for pathogens and 
other bacteria of interest, reported in Nationwide Beef Microbiological 
Baseline Data Collection Program: Steers and Heifers, reflect low 
numbers of pathogens contaminating the surface of beef carcasses. 
Staphylococcus aureus and Listeria monocytogenes were recovered from 
approximately 4% of 2,000 beef carcasses. Salmonella and Escherichia 
coli 0157:H7 were recovered from 1% and 0.2%, respectively, of more 
than 2,000 beef carcasses. Only 3.6% of the carcasses had coliform 
counts greater than 100 colony-forming units (CFU)/cm\2\ (2.0 logs) and 
6.9% of the carcasses had aerobic plate counts of over 10,000 CFU/cm\2\ 
(4.0 logs). Although raw meat containing over 10,000 CFU/cm\2\ of non-
pathogenic spoilage bacteria does not present a health risk, it is 
generally considered aesthetically undesirable, has reduced shelf-life, 
and is often viewed as having been produced unhygienically.
    Good hygienic practices during the slaughter and dressing of 
livestock are critical to safeguard the microbiological safety and 
quality of meat (Empey and Scott, 1939; Ayres, 1955; ICMSF, 1988). 
Adherence to good hygienic practices, however, does not preclude the 
presence of pathogenic bacteria on the final dressed carcass. 
Salmonella, E. coli 0157:H7, Listeria monocytogenes, and Campylobacter 
jejuni have all been recovered from hygienically-slaughtered beef 
carcasses (Stolle, 1981; Weissman and Carpenter, 1969; Chapman et al., 
1993; Loncarevic et al., 1994; Stern, 1981; Gill and Harris, 1982).
    Feces, ingesta, and milk from infected cows may contain Salmonella, 
E. coli 0157:H7, and other pathogens (Grau et al., 1968; Munroe et al., 
1983; Martin et al., 1986). Accidental carcass contamination with 
feces, ingesta, and milk is thought to be the primary route by which 
pathogens enter the food chain (Chapman et al., 1993). Removing such 
visible contamination from carcasses should reduce the risk to 
consumers but is unlikely to produce pathogen-free carcasses.
Slaughter Floor Contamination
    The main direct sources of carcass microbial contamination on the 
slaughter floor include the animal (especially the hide and feet/
hooves), dressing equipment and tools, personnel and their clothing, 
and the plant environment. Water is sometimes mentioned as a possible 
source of microorganisms, but this association is largely historical 
since contemporary abattoirs use exclusively potable water (or 
reconditioned water of equivalent microbiological quality). Similarly, 
the contribution of airborne microbes to carcass contamination on the 
slaughter floor has been mentioned, but Roberts (1980) concluded that, 
``air deposits only tens or hundreds of microorganisms per cm\2\ per 
hour, where operatives and equipment carry tens or hundreds of 
thousands--or even millions.''
    Although some microbial contamination of deep-muscle tissues may 
occur during stunning and bleeding processes when intact skin is 
broken, thus allowing bacteria to enter the bloodstream, these actions 
do not generally introduce significant numbers of bacteria (Roberts and 
Hudson, 1986). The primary source of bacterial contamination of the 
carcass is generally the hide (Empey and Scott, 1939; Ayres, 1955; 
Newton et al., 1978; Smeltzer et al., 1980a). During the initial stages 
of hide and leg removal, microorganisms present on the hide are 
transferred to subcutaneous tissue by the skinning knife. Additional 
microbes may be directly transferred to the subcutaneous tissues from 
the hide when a loose outer flap of the hide contacts the carcass 
surface during hide pulling (Mackey and Roberts, 1991). Contamination 
may also be transferred indirectly from the 

[[Page 49555]]
tools, hands/arms, and clothing of workers (Mackey and Roberts, 1991). 
A classic example is a worker holding the carcass with an unwashed hand 
that previously had been in contact with the outer surface of the hide.
    Studies have shown that workers handling hide-on beef carcasses are 
more likely to have a higher incidence and prevalence of salmonellae on 
their hands than are personnel performing other on-line tasks (Smeltzer 
et al., 1980b). Similarly, knives and other equipment used for hide 
removal are more likely to be contaminated with Salmonella than are 
implements used for other operations (Peel and Simmons, 1978; Smeltzer 
et al., 1980a). Grau (1979) found that Salmonella contamination was 
especially likely to occur when a knife was used to free the rectum and 
anal sphincter during hide removal. Studies have shown that knife 
decontamination in hot water is often an inadequate means of 
inactivating Salmonella and other bacteria on the knife surface, 
usually because of insufficient exposure time (Peel and Simmons, 1978). 
Greater than 10 seconds exposure was necessary for microbial 
inactivation when a contaminated knife was dipped in 82 deg.C water. 
Cross-contamination is reduced when knives and other implements are 
frequently decontaminated, and hands, arms, and aprons are washed and 
sanitized regularly (Norval, 1961; Childers et al., 1973; Peel and 
Simmons, 1978; Roberts, 1980; Smeltzer et al., 1980a and b; de Wit and 
Kampelmacher, 1982; Grau, 1987).
    After the removal of hide, hooves, and head, most subsequent 
microbial contamination is attributable to the hygienic practices of 
the workers or technical errors, such as puncturing the animal's 
gastrointestinal tract (Roberts, 1980). Knives and other equipment used 
for evisceration are generally less contaminated than tools used for 
hide and leg removal (Smeltzer et al., 1980a). The incidence of 
Salmonella on beef carcasses, knives, and aprons increases at the stage 
of evisceration, but to a lesser degree than during hide and leg 
removal (Stolle, 1981; Smeltzer et al., 1980a). Thorough training and 
careful evisceration practices (especially closing off the ends of the 
gastrointestinal tract and removing the intestines from the body 
cavity) are necessary to prevent carcass contamination with ingesta or 
feces (Grau, 1987; ICMSF, 1988; Mackey and Roberts, 1991).
    Microbiological contamination acquired during the slaughter and 
dressing process of livestock is not spread evenly over the carcass, 
and may be expected to vary between sides of the same carcass, between 
different carcasses processed on the same day at an abattoir, between 
carcasses produced on different days at an abattoir, and between 
carcasses produced at different establishments (Empey and Scott, 1939; 
Kotula et al., 1975; Ingram and Roberts, 1976; Roberts 1980; Johanson 
et al., 1983). This variability can be due to a number of factors, such 
as differences in dressing methods, worker skill, application of 
washing or other carcass treatments, season of the year, and weather.

III. Attachment of Bacteria

    The rate of attachment, growth, and multiplication of bacteria on 
carcasses is dependent on the structure, composition, and water 
activity of the exposed tissues, the acidity of the surface, the 
temperature of air and the carcass, the bacterial strain, and various 
bacterial attachment mechanisms (Lillard, 1985). The skinned ``hot'' 
beef carcass provides an ideal environment for bacterial survival and 
multiplication. Surfaces of chilled carcasses, especially those that 
have experienced significant dehydration, may be less attractive sites 
for bacterial attachment.
    The process by which bacteria attach to meat surfaces is believed 
to consist of two stages. The first stage is where bacteria are either 
attached by weak physical forces or freely floating in the water film 
that covers the meat surface. The second stage is characterized by a 
stronger attachment mechanism involving, in part, the formation of 
polysaccharides over time (Firstenberg-Eden, 1981). This consolidation 
stage is followed by colonization or growth of the microbes on the meat 
tissue. Once attachment and colonization have occurred, it is very 
difficult to completely remove pathogenic microorganisms from meat or 
poultry surfaces by normal processing methods (Benedict et al., 1991).
    There is considerable variability among bacteria in their ability 
to attach to different surfaces. This is likely to be a reflection of 
the different mechanisms (including pili, flagella, extracellular 
polymers) used by different bacteria. It has been suggested that 
bacteria from feces attach more strongly and in higher numbers than the 
same bacteria grown in laboratory media or meat surfaces (Notermans et 
al., 1980). Enhanced binding by bacteria present in feces may have to 
be considered when evaluating the efficacy of carcass decontamination 
treatments.
    It appears that specific bacterial binding sites (receptors) exist 
on animal cells. Collagen, in particular, seems to be a target for 
bacterial attachment (Mattila and Frost, 1988; Benedict et al., 1991). 
Notermans and Kampelmacher (1983) concluded that attachment cannot be 
completely prevented by manipulating water sprays or baths through the 
addition of chemicals or manipulating pH. Therefore, the only way to 
absolutely prevent attachment is to prevent contact between bacteria 
and meat. While bacteria are still freely floating in the water film, 
they can be displaced using clean water (Notermans and Kampelmacher, 
1983). Measures designed to block attachment should be applied as soon 
as possible following contamination. Two points on the slaughter line 
that appear to be likely sites for the application of carcass sprays 
are following hide removal and following evisceration.

IV. Methods To Decrease Carcass Contamination

    In addition to trimming as a means of removing bacteria associated 
with visible contamination, bacteria are removed from carcasses by 
several recommended methods, such as rinsing or washing with water 
(both hot and ambient temperatures), either with or without one of 
several approved food-grade organic acids (lactic, acetic, or citric) 
or chemical sanitizers, such as chlorine. Each of these factors is 
reviewed in the following sections for its relevance to beef carcass 
decontamination.
A. Water Rinsing
    Rinsing a carcass can remove physical contamination (dirt, hair, 
fecal matter, etc.) to a varying degree, carrying with it some of the 
resident microorganisms. As indicated above, interventions of this type 
or others that physically remove bacteria should be used as early as 
possible after likely introduction of contamination (e.g., after hide 
removal) to prevent or retard bacterial attachment and growth. Various 
factors associated with rinsing carcasses can be manipulated, 
increasing the effectiveness of this approach. Major factors include 
water temperature, water pressure, line speed, and method of 
application (Anderson et al., 1979; Crouse et al., 1988). While 
numerous studies have examined the efficacy of washing techniques, most 
investigations have been conducted under research conditions, and only 
a few have directly evaluated effectiveness in production settings.
    The use and timing of hot water (95 deg. C) application during 
processing were investigated by Barkate et al. (1993) to determine 
effectiveness in reducing the numbers of naturally 

[[Page 49556]]
occurring bacteria on beef carcass surfaces. They found a 1.3 
log10 CFU/cm2 reduction in aerobic plate counts (APCs) for 
samples sprayed with hot water before the final carcass rinse as 
compared to a 0.8 log10 CFU/cm2 reduction in samples sprayed 
with hot water after the final rinse. The fact that fewer bacteria were 
removed from the samples sprayed with hot water after the final rinse 
may have been due to the length of time (approximately 15 to 20 
minutes) that elapsed before hot water was applied. In this connection, 
the authors interpreted Butler et al. (1979) as indicating that the 
time lapse may have allowed more bacteria to become attached and more 
resistant to the lethal effects of hot water.
    Anderson et al. (1979) reported that under laboratory conditions, 
bacterial counts were reduced 1.0 and 2.0 log10 CFU/cm2 when 
beef plates were treated with cold (15.6 deg. C) and hot (76-80 deg. C) 
water, respectively. During subsequent storage at 3.3 deg. C, the time 
to reach microbial spoilage (108 CFU/cm2) was 6 days with cold 
water and 12 days with hot water. The untreated controls took 7 days to 
reach spoilage levels.
    Smith and collaborators (Smith and Graham, 1978; Smith, 1992; and 
Smith and Davey, 1990, and Smith et al., 1995) have investigated the 
effectiveness of hot water (140 deg. F) washes versus a more commonly 
used wash temperature (100 deg. F). Hot water was effective against 
pathogens such as E. coli 0157:H7, Salmonella, Yersinia enterocolitica, 
and L. monocytogenes. Quantitative studies assessing the effect of hot 
water treatment on the survival of E. coli 0157:H7 indicated that 
levels on artificially inoculated carcasses are reduced by 84-99.9% 
(Smith, 1992; Smith and Davey, 1990; Smith et al., 1995) Other studies 
have reported reductions in E. coli biotype 1 as great as 99-99.9% 
(Davey and Smith, 1989).
    Hot water sprays are most effective when the water film on the 
carcass surface is raised to 82 deg. C (180 deg. F) for at least 10 
seconds. If beef tissue is exposed to this temperature for more than 10 
seconds, the surface of the fat and lean tissues can become gray to a 
depth of about 0.5mm. These carcasses, however, regain their normal 
color after chilling (Smith and Graham, 1978; Barkate et al., 1993; 
Patterson, 1969). Carcass bloom, however, is permanently and adversely 
affected if exposed for 20 seconds to temperatures above 81.4 deg. C-
82 deg. C (Davey, 1989, 1990; Barkate et al., 1993). Lower temperatures 
applied for longer periods of time also have been found (Davey and 
Smith, 1989) to permanently affect bloom.
    Similar results have been reported by investigators worldwide. 
Patterson (1970) sprayed beef carcasses with steam and hot water at 
176-204.8 deg. F (80-96 deg. C) for two minutes, applying in the case 
of water 18.9 liters to each carcass at a distance of one foot (25cm), 
to determine the effectiveness of hot water in reducing carcass 
contamination. Although some discoloration of the carcass occurred 
initially, cooling for 24 hours restored normal color. Approximately a 
log reduction in total plate count was observed; however, there was no 
significant reduction in fecal streptococci. A differential in 
bacterial counts between treated and untreated carcasses was still 
evident after 48 hours of refrigerated storage. Smith and Graham (1974) 
used beef and mutton samples inoculated with E. coli to compare the 
effectiveness of hot water treatment, steam chamber, steam injection, 
or washing with water at 37 deg. C (91 deg. F) on microbial levels and 
carcass color changes. Water temperatures below 60 deg. C (140 deg. F) 
produced no significant color change. As temperatures rose above 
85 deg. C (176 deg. F), there was permanent and marked color change. 
Very high temperatures of 95 deg. C (194 deg. F) for three minutes 
changed the surface coloration to a depth of no more than 0.5mm below 
the surface. Temperatures equal to or greater than 70 deg. C (158 deg. 
F) produced a 2 log10 (99%) reduction of E. coli.
    Water can be applied to a carcass, by either hand or machine, using 
washing, spraying, or dipping. Hand and machine washing were compared 
by Anderson et al. (1981). Hand-washed carcasses had reductions of 0.99 
log10 CFU/cm2, while an experimental beef carcass washing 
unit yielded a 1.07 log10 CFU/cm2 reduction, a non-
significant difference.
    The angle of water impact has been shown to be an important factor 
in bacterial removal. When water pressure is normal, a 30 deg. angle is 
more effective at removing bacteria than a 90 deg. angle (Anderson 
1975). When line pressure is increased, the angle degree is less 
important.
    Since bacterial attachment affects the ease of removing bacteria, 
the point during slaughter and dressing at which water is applied has 
been deemed significant in retarding or inhibiting attachment. 
Notermans et al (1980) concluded that control of Enterobacteriaceae and 
salmonellae was more effective when carcasses were spray-cleaned with 
water at multiple stages during evisceration than when washing occurred 
only after evisceration.
    Water pressure can influence the effectiveness of carcass washing 
treatments. De Zuniga et al (1991) investigated the effect of increased 
water pressure on the penetration of bacteria into tissue using Blue 
Lake dye. As the pressure of the water increased, the dye penetrated to 
a correspondingly greater depth in the tissue. They recommended an 
optimal water pressure for washing beef carcasses between 100 psi to 
300 psi. They cautioned that higher pressures may drive the organisms 
deeper into the tissues, while pressures less that 100 psi were less 
effective at reducing bacterial counts. Kotula (1974) found that water 
containing 200 ppm chlorine, sprayed at a pressure of 355 psi and at 
temperatures ranging from 55-125 deg. F, effectively removed bacteria 
from market beef forequarters. Kotula et al. (1974) concluded that 
water pressure was a more important variable than pH or water 
temperature for removing bacteria by spray washing. These beef samples, 
however, were not freshly slaughtered, and may have required more 
intense pressures. Jerico et al. (1995), concluded that washing beef 
carcasses with water at 200-400 psi at 38 deg.C (100.4 deg.F) did not 
significantly change the level of bacteria on the carcass. They noted 
that other investigators (Anderson, 1981; Kotula et al., 1974; Crouse 
et al., 1988) did not statistically validate the sample size to adjust 
for variation in counts and sample size, and did not collect samples 
immediately after washing.
    Increasing water pressures has been found to have certain 
operational disadvantages. For example, greater pumping pressure is 
required, thus requiring more energy and special equipment, less heat 
energy can be recovered from the outlet water steam, and the nozzle is 
more likely to become blocked if water is recirculated (Graham et al., 
1978).
B. Beef Carcass Trimming vs. Washing Treatment Studies
    Only three studies directly compare hand trimming vs. washing as 
methods to remove fecal and bacterial contamination from beef 
carcasses. Hardin et al. (1995) conducted an FSIS-supported research 
project designed to compare traditional hand trimming procedures to 
washing of beef carcasses for removal of feces and associated bacteria. 
Paired cuts from four carcass regions (inside round, outside round, 
brisket, and clod) were removed from hot, split carcasses, then 
contaminated with a fecal suspension containing either E. coli 0157:H7 
or S. typhimurium (10 \6\ CFU/ml). Inoculated meat cuts 

[[Page 49557]]
(400 cm\2\ area) were treated by one of four treatments either 
immediately or 20-30 min post-contamination. One paired contaminated 
surface region from each carcass side was trimmed of all visible fecal 
contamination. The remaining paired carcass surface region was then 
washed either with water (35 deg.C/95 deg.F), water wash with 2% lactic 
acid (55 deg.C/131 deg.F), or water wash with 2% acetic acid (55 deg.C/
131 deg.F). Samples for microbiological analyses were collected pre- 
and post-treatment from within and outside the defined area 
contaminated with the fecal suspension.
    All treatments significantly reduced levels of pathogens; however, 
decontamination was affected by carcass surface region. The inside 
round region was the most difficult carcass surface to decontaminate, 
regardless of treatment. Washing followed by organic acid treatment 
performed better than trimming or washing alone on all carcass region 
surfaces except the inside round, where organic acid treatments and 
trimming performed equally well. Overall, 2% V/V lactic acid reduced 
levels of E. coli 0157:H7 significantly better than 2% V/V acetic acid; 
however, differences between the abilities of the acids to reduce 
Salmonella were less pronounced. All treatments caused minimal spread 
of pathogens outside the initial area of fecal contamination. Recovery 
after spreading was reduced by the use of organic acid treatments.
    This study is limited in relation to evaluating commercial 
conditions due to the experimental design, which deliberately added 
inoculated feces to the carcass. A rather large area (400 cm\2\) was 
inoculated and deliberate placement on the meat surface allowed the 
trimmer to know exactly where fecal contamination occurred. Under 
commercial situations, fecal contamination must first be visually 
located and the borders of contamination subjectively evaluated. This 
subjectiveness may allow the trimmer to inadvertently touch the knife 
to areas of fecal contamination that are not obviously visible, thereby 
cross-contaminating the freshly trimmed areas as the knife blade is 
drawn across. Knife trimming was highly controlled in these 
experiments, whereas knife trimming under commercial conditions might 
be expected to yield more variable results. Secondly, although this 
study was performed in an abattoir, the treatments were performed in an 
adjacent laboratory setting rather than on a slaughter line where 
deliberate inoculation of carcasses with pathogens is not allowed by 
FSIS.
    The second direct comparison of trimming vs. washing involved work 
performed by scientists from four universities. This study was 
conducted in four phases, and is commonly referred to as the National 
Livestock and Meat Board study, for the organization that funded the 
project.
    Phase I trials sought to define the proper parameters for the 
washing experiments (Gorman et al., 1995, submitted for publication; 
Smith et al., 1995, submitted for publication; Smith, 1995). Results of 
Phase I suggested that higher pressures of 20.68 bar (300 psi) and 
27.58 bar (400 psi) during spray-washing were more effective (P<0.05) 
than lower pressures of 2.76 bar (40 psi) or 13.79 bar (200 psi) bar 
for removal of fecal material and for reducing bacterial numbers. Phase 
II compared the efficacy of hand-trimming and six potential carcass 
decontamination treatments: hot water (74 deg.C), ozone, trisodium 
phosphate, acetic acid, hydrogen peroxide, and a commercial sanitizer 
(Smith, 1995; Gorman et al., submitted for publication).
    Data from Phase II revealed that application of hot water (74 deg.C 
at the meat surface) for spray-washing reduced total plate counts and 
E. coli (ATCC 11370) counts exceeding 3.0 log10 CFU/cm2. The 
best combination and sequence of interventions for reducing bacteria 
counts on beef brisket samples were: (a) Use 74 deg.C water in the 
first wash with water pressure at 20.68 bar, and (b) if colder 
(<35 deg.C) water is used in the first wash, spray-wash with hydrogen 
peroxide or ozone in the second wash. Trimming alone or trimming 
followed by a single spray-washing treatment of plain water (16-
74 deg.C; 20.68 bar; 12 or 36 sec) significantly (P<0.05) reduced the 
microbiological counts compared to the untreated, inoculated control. 
Trimming alone decreased total aerobic plate counts by 2.5 CFU/cm2 
and trimming with plain water (<35 deg.C) wash decreased total aerobic 
plate counts by 1.44-2.3 CFU/cm2. These data indicated that 
trimming reduces microbiological contamination after carcasses are 
contaminated with fecal material but a significant amount of 
contamination remained on samples after trimming or trimming with spray 
washing. It was concluded that washing at 300 psi was as effective as 
trimming and washing combinations for reducing bacterial counts on the 
tissues. When water was 74 deg.C, reductions were greater than 3.0 log 
CFU/cm2, irrespective of the presence or absence of chemical 
sanitizer.
    Spray-washing with hot water resulted in less variability in 
bacterial counts obtained after treatment compared to hand-trimming 
and/or spray-washing with water of lower temperatures. The authors 
concluded that this greater variability in bacterial counts for hand-
trimming treatments indicated the potential for cross-contamination 
during the process.
    Phase IIIA consisted of field studies in six commercial plants and 
concluded that: (a) Compared to inoculated controls (no trim; no wash), 
every combination of washing--with or without trimming and with and 
without chemical agents--lowered (P<0.05) total plate counts and E. 
coli counts; (b) compared to the treatment combining trimming plus 
washing, washing (without trimming) with 74 deg.C water achieved 
(P<0.05) equal reductions in total plate counts and E. coli counts; 
and, (c) washing (without trimming) with 74 deg.C water--based upon 
comparative standard deviations--achieved more consistent lowering of 
total plate counts and of E. coli counts than did trimming plus washing 
(Smith, 1995).
    Phase IIIB further investigated the effects of hot water washing 
under commercial slaughter conditions, as the hot water washing trials 
in Phase III were conducted in only two of the six plants, the number 
of samples was small, and the parameters of hot water application 
(temperature, pressure, etc.,) were not consistent (Smith, 1995). The 
results of Phase IIIB were consistent with Phase IIIA in demonstrating 
that trimming and washing are effective in reducing the microbial loads 
on carcasses. Of the several treatments tested, however, the most 
effective in reducing microbial numbers was combined trimming, washing, 
and rinsing with hot water for 8 seconds. Other treatments tested 
included: control (no trimming, no washing), trimming/washing (current 
``zero tolerance'' procedure), no trimming/hot water rinse for 2.5 
seconds, and no trimming/hot water rinse for 8 seconds.
    The use of hot water alone (no trimming) in this study effectively 
reduced the microbial contamination on carcasses, but the average 
reduction in counts was slightly less than that achieved by trimming 
and washing or trimming and washing combined with hot water rinsing. 
These findings suggest that the application of hot water at 20 pounds 
per square inch (psi) for 2.5 or 8 seconds is not as effective as the 
hot water washing system used in Phase IIIA of the studies, i.e., the 
application of a fine spray at psi's ranging from 150 to 260 and 
temperatures of 60 deg.C to 75 deg.C (140 deg.F to 175 deg.F). 

[[Page 49558]]

    The third study that evaluated the effectiveness of carcass 
trimming and/or washing on the microbiological quality of beef 
carcasses in a commercial slaughter plant was conducted by Prasai et 
al. (1995). The inside rounds of 48 beef carcass sides were evaluated 
using four treatments: (1) Untreated (no trim, no wash), (2) trim 
alone, (3) trim plus wash, or (4) wash alone. Samples for aerobic plate 
counts, E. coli, and coliform counts were collected post treatment. 
Significant differences (P< 0.05) were observed in aerobic plate counts 
(APC) when treatments were compared to controls. E. coli and coliform 
counts were too low to show statistical significance between 
treatments; however, the mean E. coli and coliform counts were higher 
in control samples (P< 0.05) than in other treatments. The greatest 
reduction in APC counts were observed in trimmed samples (3.0 log CFU 
reduction vs. control), followed by trim and wash (0.9 log CFU 
reduction vs. control), and wash alone (0.3 log CFU reduction vs 
control) samples. Samples receiving trim and wash treatments had APC 
counts approximately 2 logs higher than trimmed samples, suggesting 
that washing spreads bacterial contamination. All washed samples, 
however, had mean reductions of 0.3-0.9 log CFU vs. control samples. 
The investigators concluded that trimming can be effective in reducing 
bacterial contamination during slaughter and that additional bacterial 
reductions can be obtained if trimming instruments are sanitized 
between trim sites. The authors further concluded, however, that the 
type of trimming used in the study--i.e., use of sterile instruments 
and trimming of entire sample surface--is unlikely on a typical 
slaughter line, and that, under commercial conditions, a combination of 
trimming and washing could be practical and effective.
C. Organic Acid Sprays
    Organic acids, such as lactic, acetic, and citric, reduce 
pathogenic and spoilage microbial organism populations by altering the 
environmental pH and by direct bactericidal action (Osthold, 1984). The 
immediate effect of organic acids on bacteria is to reduce numbers 
approximately one log10 when the initial aerobic plate count (APC) 
is less than or equal to 104 CFU/cm2. A few investigators have 
reported a two or three log reduction (Snijders, 1979; Smulders and 
Woolthius, 1983; Netten, 1984). Overall, the available scientific data 
indicate that treating carcasses with an organic acid rinse, spray, or 
dip can achieve a 90-99.9% (1-3 log10) reduction in the level of 
spoilage organisms such as Pseudomonas fluorescens (Dickson and 
Anderson, 1992; Prasai et al., 1991; Frederick et al., 1994). 
Decontaminating carcasses with lactic or acetic acid can extend the 
shelf life of treated product (Smulders and Woolthuis, 1985; Woolthius 
and Smulders, 1985). In addition, organic acid sprays and dips have 
been shown to decrease the levels of specific pathogens, such as 
Salmonella spp., Staphylococcus aureus, C. jejuni, Yersinia 
enterocolitica, and L. monocytogenes (Osthold et al., 1984; Bell, et 
al., 1986; Smulders, et al., 1986; Anderson, et al., 1987; Siragusa and 
Dickson, 1992; and Cutter and Siragusa, 1994). Reductions in the number 
of pathogenic bacteria on carcasses reduce the risk of food-borne 
disease.
    Each organic acid differs in its ability to reduce the bacterial 
population on tissue surfaces. The concentration of the organic acid 
affects not only bacterial survival, but also the color and odor of the 
meat, especially if the concentration is 2% or greater. Bleaching and 
discoloration of tissue have been reported, and may occur at 1% 
concentrations for lactic and acetic acid (Smulders and Woolthuis, 
1985, and Hamby et al., 1987). Balancing antimicrobial activity with 
organoleptic impact, the practical concentration for use of lactic or 
acetic acids appears to be 0.5 to 2.5%.
    Prasai et al. (1991) examined the effect of lactic acid (1.5%, 
55 deg.C) applied to beef carcasses at various locations in processing 
and found that the greatest reduction in APCs occurred on carcasses 
treated immediately after hide removal and again after evisceration. 
These reductions, however, were not significantly better than spraying 
only after evisceration. After 72 hours of storage (1 deg.C), the 
number of bacteria per cm2 on treated carcasses was lower than on 
comparable control carcasses. Decontamination with acids is more 
effective when employed as soon after slaughter as feasible (Acuff et 
al., 1987) and at elevated temperatures (53-55 deg.C).
    Treating beef carcasses with acids does not completely inactivate 
all pathogens, particularly E. coli 0157:H7, which is relatively acid 
tolerant. Cutter and Siragusa (1992) reported that there are 
differences among E. coli 0157:H7 isolates in relation to their acid 
tolerances. Salmonella spp., L. monocytogenes, and Pseudomonas 
fluorescens are more sensitive to acids than E. coli 0157:H7 (Dickson, 
1991; Greer and Dilts, 1992; Cutter and Siragusa, 1994; Bell et al., 
1986); while E. coli biotype 1, particularly E. coli 01257:H7, appears 
to be among the more resistant enteric bacteria to the effects of 
organic acids (Woolthuis et al., 1984; Woolthuis and Smulders, 1985; 
Van Der Marel et al., 1988; Bell et al., 1986; Anderson and Marshall, 
1990, 1989; Acuff et al., 1994).
    The extent of reduction of E. coli 0157:H7 achieved has varied 
among studies. For example, Dickson (1991) found that the reduction of 
E. coli 0157:H7 was similar to that observed for Salmonella and L. 
monocytogenes, with up to a 99.9% reduction in the levels of all three 
bacteria from inoculated tissues. A number of other studies have 
reported reductions in E. coli and in Enterobacteriaceae (which belongs 
to the same family as E. coli) of 46 to 99.9% on tissues treated with 
1.2% to 2% acid (Bell et al., 1986; Anderson and Marshall, 1990, 1989; 
Cutter and Siragusa, 1994; Greer and Dilts, 1992; Acuff et al., 1994). 
Anderson and Marshall (1990) found that although lactic acid exerted a 
significant antimicrobial effect on some Enterobacteriaceae, it did not 
appreciably affect E. coli or S. typhimurium on beef issue samples. 
Conversely, Brackett et al. (1993) reported that up to 1.5% acid 
treatments did not appreciably reduce E. coli 0157:H7, whether at 20C 
or 55C, and was ``of little value in disinfecting beef of EC 0157.'' 
Dickson (1991) concluded that an acetic acid carcass sanitizer could be 
used as an effective method to control bacterial pathogens. Cutter and 
Siragusa (1992) reported that the reduction of E. coli 0157:H7 on meat 
by acid treatment is dependent on acid concentration (5% giving the 
greatest reduction) and tissue type (greater reduction on fat tissue 
than lean). They found lactic acid to be more effective than acetic or 
citric acid against E. coli. This has been reported by Hardin et al., 
1995, as well. Cutter and Siragusa (1992) suggested that the two 
primary determinants of effectiveness are the pH achieved at the 
surface of the carcass and the corresponding period of exposure.
    A number of other studies have reported reductions in E. coli or 
Enterobacteriaceae ranging from 46 to 99.9% on tissues treated with 
1.2% to 2% acid (Bell et al. 1986; Anderson and Marshall, 1990, 1989; 
Cutter and Siragusa, 1994; Greer and Dilts, 1992; Hardin et al., 1995). 
Anderson and Marshall (1990) found that concentration and temperature 
of lactic acid solutions had significant but independent effects on 
reduction in numbers of inoculated microorganisms (aerobes, 
Enterobacteriaceae, and E. coli) on the surface of lean beef muscle. E. 
coli cells, however, were 

[[Page 49559]]
comparatively resistant to the effects of temperature and concentration 
of lactic acid. Further, Brackett et al. (1993) reported that up to 
1.5% acid treatments did not appreciably reduce E. coli 0157:H7, 
whether at 20 deg. or 55 deg.C and ``was of little value in 
disinfecting beef of EC O157.'' Brackett (1994) also concluded that E. 
coli (Biotype I) and E. coli 0157:H7 are quite resistant to the effects 
of organic acids, particularly lactic acid. Hardin et al. (1995) 
observed that E. coli 0157:H7 was more resistant than S. typhimurium to 
the effects of both 2% lactic and 2% acetic acid applied to beef 
carcass surface regions. Reductions in levels of E. coli 0157:H7 were 
0.6-1.5 log10 CFU/cm2 greater with lactic acid than acetic 
acid, depending on the carcass surface tested. Both lactic and acetic 
acid, however, were equally effective in reducing levels of S. 
typhimurium.
    Both acid concentration and temperature have been studied for their 
effects on reducing bacterial numbers on beef tissue. Anderson and 
Marshall (1989) observed that both concentration and temperature 
produced significant, but independent, reductions in numbers of E. coli 
and S. typhimurium on beef semitendinosus muscle dipped in an acetic 
acid solution. Acid concentration (1, 2, 3%) was found to be 
insignificant at the higher temperature (70 deg.C), but caused 
significant reduction in numbers of microorganisms at lower 
temperatures (22, 40, and 55 deg.C). Anderson and Marshall (1989) 
reported that the most effective treatment was dipping pieces of lean 
meat in 3% acetic acid at 70 deg.C. They suggested that some direct 
effects from heat may have contributed to the increased reduction of 
bacterial numbers in samples treated at this higher temperature. The 
numbers of surviving organisms were reduced as the temperature of the 
acid was increased from 25 to 70 deg.C, with acid concentration being 
less significant at higher temperatures. These researchers later 
reported similar results for treatments using 3% lactic acid at 
70 deg.C (Anderson and Marshall, 1990). Anderson et al. (1987) observed 
a greater reduction in levels of indigenous E. coli, Enterobacteriaceae 
and APC with hot (52 deg.C) acetic acid when compared to cool 
(14.4 deg.C) acetic acid.
    In a more recent study, Anderson et al. (1992) reported an 
increased removal of bacteria as either the concentration or 
temperature of the acid solution was increased, with the acids 
performing differently at different temperatures. Lactic acid was 
reported to be significantly more effective than acetic acid for all 
bacterial types (aerobes, Enterobacteriaceae, S. typhimurium, E. coli) 
at both 20 and 45 deg.C, and more effective on S. typhimurium at 
70 deg.C. Cutter and Siragusa (1994) reported that of three 
concentrations evaluated (1, 3, and 5%), 5% acid (acetic, lactic, or 
citric) resulted in the greatest reduction in numbers of both E. coli 
0157:H7 and P. fluorescens from beef carcass tissue.
    Evaluation of the overall effectiveness of organic acids is 
confounded by the fact that the various studies have employed different 
acid types, applied at different concentrations and temperatures to 
varying types of meat tissue surfaces. Each of these factors has an 
effect on the removal of bacteria from carcasses. Several studies have 
evaluated the effect of tissue type (fat and lean) on the effectiveness 
of organic acids to reduce the number of bacterial cells from beef 
tissue surfaces. Cutter and Siragusa (1994) reported that the magnitude 
of bacterial reductions from beef surfaces treated with organic acids 
was consistently greater when spray treatments were applied to bacteria 
attached to adipose tissue. Log reductions for E. coli 0157:H7 and P. 
fluorescens were 1 and 2 log10 greater on adipose vs. lean beef 
carcass tissue. These findings agree with Dickson and Anderson (1991), 
who reported significant reductions in S. california from use of 
distilled water and 2% acetic acid with beef fat tissue, whereas no 
significant differences were observed between treated and untreated 
lean tissues. Dickson (1991, 1992) reported similar findings for S. 
typhimurium, L. monocytogenes, and E. coli 0157:H7 attached to fat 
surfaces of beef trim. Acid treatment resulted in an immediate 
sublethal injury of approximately 65% of S. typhimurium (Dickson, 1992) 
remaining on lean and fat tissue. A residual effect from the acid was 
observed with the fat tissue, resulting in an additional 1 log \10\ 
decrease over four hours. The author suggested that the differences 
observed in the effects of acid for lean and fat tissue were due to the 
increased water content of lean tissue and the presence of water-
soluble components that may neutralize the acid and its effect on the 
bacterial cell. In a comparison of methods for the removal of S. 
typhimurium and E. coli 0157:H7 from various beef carcass surfaces, 
Hardin et al. (1995) found a significant difference in the type of 
surface evaluated. The researchers observed that the inside round was 
the most difficult carcass surface to decontaminate and attributed this 
to a substantial amount of exposed lean on the meat surface, as well as 
a pronounced collar of fat at the edge of the lean.
    Organic acids have been reported to be more effective in reducing 
bacterial levels when applied during, or shortly after, slaughter and 
dressing. Acuff et al. (1987) and Dixon et al. (1987) reported no 
significant difference in reduction of aerobic populations from beef 
steaks and subprimals treated post-fabrication with various organic 
acids and their controls. They suggested that the application of acid 
decontamination would be most effective as soon as possible after 
slaughter, before bacteria have had a chance to attach firmly to meat 
surfaces. This was supported by Brackett et al. (1994), who recently 
reported that hot acid sprays were ineffective in reducing levels of E. 
coli 0157:H7 inoculated onto the surface of sirloin tips purchased from 
local butchers. Snijders et al. (1985) reported an increase in the 
bactericidal effect of lactic acid sprayed on hot carcasses (45 minutes 
postmortem) when compared to spraying on chilled carcasses. They 
suggested that on hot carcass surfaces, increased reductions may be due 
to higher levels of bacteria present in the water film and not yet 
attached to the carcass surface. Van Netten et al. (1994) described an 
in vitro model to evaluate the inactivation kinetics of bacteria from 
meat surfaces treated with lactic acid. A rapid reduction in bacterial 
numbers due to the replacement of the fluid (water film) on a warm meat 
surface by a film containing lactic acid was referred to as ``immediate 
lethality.'' They proposed that organisms on chilled meat are less 
accessible to lactic acid and are better protected by meat buffering 
effects than those in the fluid film of hot meat surfaces.
D. Chlorine and Chlorine Compounds
    Chlorine, chlorine dioxide, sodium hypochlorite, and hypochlorous 
acid all have been sprayed onto beef carcasses in an effort to reduce 
microbial populations.
    Chlorine and chlorine dioxide were compared for chickens by Lillard 
(1979) to determine their relative bactericidal effect. Chlorine 
dioxide was found to be more potent than chlorine and required only 
one-seventh as much to produce the same bactericidal effect. Further, 
chlorine dioxide maintained its effectiveness when both pH and the 
level of organic matter increased. Chlorine is less effective when the 
pH or organic load is increased. Kotula et al. (1974) treated beef 
forequarters with chlorinated water (200 ppm) and found initial 
reductions (45 min post-treatment) in APCs for duplicate testing days 
of 1.5 and 2.3 log10 CFU/cm2, respectively. Temperature (12.8 
vs 51.7 deg.C) and pH (4 to 7) were found to 

[[Page 49560]]
significantly affect efficacy, with the greatest reductions observed at 
a temperature of 51.7 deg. and pH values of 6 and 7.
    Anderson et al., (1979) compared the effectiveness of several 
treatments to reduce APCs on previously frozen beef plate stripes. Meat 
was washed and sanitized with cold water (15.6 deg.C [60 deg.F]), hot 
water (76-80 deg.C [168-176 deg.F]) (14kg/cm2), sodium 
hypochlorite (200-250g/ml), or acetic acid (3%)--all at 14kg/
cm2; and at 17 kg/cm2 steam at 95 deg.C (194 deg.F). They 
found that the sodium hypochlorite and cold water treatments reduced 
counts by about one log. Steam reduced the count by only 0.06 log. Hot 
water reduced counts by 2.0 log and acetic acid reduced counts by 1.5 
log. Over time, samples treated with hypochlorite had rates of 
bacterial re-growth that exceeded those of the untreated controls. 
Steam and cold water treated samples exceeded APCs on controls after 
five days, presumably due to greater surface moisture from the 
treatment. Growth rates associated with the hot water samples were 
similar to the untreated controls, but, because of the initial 2.0 log 
reduction in microbial levels, it took nearly five additional days 
before counts reached 108/cm2. Acetic acid, applied to 
samples after a cold water wash, provided a 14-16 day delay before 
counts returned to initial levels, and it took a full 23-24 days before 
the bacteria reached 108/cm2.

V. Other Technologies

    Several other approaches or technologies have been suggested as 
additional alternative means for decontaminating beef carcasses, such 
as rinsing with trisodium phosphate (TSP), steam pasteurization of 
carcasses, steam vacuuming, and chemical dehairing. These approaches 
have not been as extensively investigated and reported in the 
scientific literature to date, relative to their use with beef 
carcasses. A brief discussion of each method follows.
A. Trisodium Phosphate
    Trisodium phosphate (TSP) has been shown to reduce Salmonella on 
processed poultry carcasses. In a 1991 patent, Bender and Brotsky 
presented the claim that trisodium phosphate (Na3PO4) could 
successfully reduce Salmonella on processed poultry carcasses. Since 
then, industry, university, and USDA Agricultural Research Service 
researchers have conducted studies that demonstrate reductions in 
Salmonella levels on poultry carcasses ranging from 90 to greater than 
99.9% (1.2 to 8.3 log10). Dickson et al. (1994) studied the effect 
of TSP on beef tissue dipped in TSP after inoculation with both Gram 
positive (L. monocytogenes) and Gram negative (S. typhimurium and E. 
coli 0157:H7) pathogens. They reported reductions of 1 to 1.5 
log10 for the Gram-negative pathogens, and a maximum reduction of 
less than one log10 for L. monocytogenes on lean tissue. Reduction 
of L. monocytogenes was greater on fat tissue: 1.2 to 1.5 log10. A 
reduction of 2 to 2.5 log10 for S. typhimurium and E. coli 0157:H7 
on fat tissue was reported.
    In-plant testing of TSP on beef carcasses (Rhone-Poulenc) showed a 
greater than 1.5 log10 reduction of E. coli (biotype I). Further, 
they found that incidence rates for E. coli fell from 51.3% on 
untreated carcasses to 1.3% on TSP-treated carcasses. The level of 
Enterobacteriaceae was reduced by one log10, and the incidence 
rates fell from 75% on untreated carcasses to 8.8% on treated 
carcasses. Salmonella was not detected on any carcasses.
B. Steam Pasteurization
    A patent-pending process developed by Frigoscandia for steam 
pasteurization of meat and poultry has been tested at Kansas State 
University and has received approval by FSIS for in-plant evaluation; 
the process is applied at the end of beef dressing operations on 
inspected and passed carcasses. A request by Frigoscandia to evaluate 
and test the process as an antimicrobial reduction intervention is 
being considered by FSIS.
    Tests of a prototype unit at Kansas State University showed that 
the process consistently reduces pathogenic bacteria, including E. coli 
0157:H7, by 99.9% (Frigoscandia, 1995). The process uses pressurized 
steam applied uniformly to the entire carcass surface, producing 
surface meat temperatures of 77-93 deg.C (170-200 deg.F) and a uniform 
bacterial reduction on the entire carcass. Since the steam reaches all 
exposed surfaces, the reduction is more uniform and operator-
independent. The process is reported to not affect the color of the 
carcass, and to use less energy than is required for a comparable hot 
water system. Furthermore, the use of a 2% lactic acid cooling spray 
immediately after steam application appeared to act synergistically to 
inactivate surface bacteria. It should be noted that the intended use 
of the steam pasteurization is not the direct physical removal of 
visible contamination, but the technology has the potential to be 
integrated into pathogen control systems to enhance their 
effectiveness.
C. Steam Vacuuming
    Alternative methods for removing beef carcass contamination such as 
air jets and vacuum systems (without steam) have been shown to be 
effective in removing visible as well as microbiological contamination 
(Monfort, 1994). Steam vacuuming is a refinement of this approach, 
combining physical removal with microbial inactivation. Steam vacuuming 
is a process in which steam and hot water are applied through nozzles 
to the carcass surface after the hide is removed. This appears to be 
particularly useful for opening cuts, which are made in the hide to 
facilitate hide removal. These carcass surfaces tend to be contaminated 
more frequently than other areas of the carcass. Steam vacuuming treats 
these surface areas with hot water (above 160 deg.F) and steam while 
vacuuming the removed contamination and any excess water from the 
surface. The process of steaming the opening patterns encountered some 
difficulty in early trials when the steam nozzle was held 6 to 12 
inches from the surface. There was a rapid drop in temperature, and as 
a result no significant differences in bacterial levels were noted from 
treated areas. These problems were corrected by adjusting the equipment 
and placing the head of the vacuum directly on the surface. Testing at 
Kansas State University has shown the effectiveness (>99.9% reduction) 
of steam vacuuming in decontaminating prerigor meat surfaces that have 
been inoculated (approximately 105 CFU/cm2) with the 
pathogens L. monocytogenes, E. coli 0157:H7, and S. typhimurium. 
Scientists at the U.S. Meat Research Center of USDA's Agricultural 
Research Service at Clay Center, Nebraska have reported a 3.0 to 3.5 
log (>99.9%) reduction in bacteria on steam vacuum-treated meat. 
Preliminary results from an ongoing industry study (ten plants reported 
to date) comparing steam vacuuming and knife trimming to remove carcass 
contamination indicate that carcasses that have been steam vacuumed 
have approximately 90% (0.94 log) less bacteria than trimmed carcasses 
in the areas tested. Several inplant trials comparing steam vacuuming 
versus traditional trimming are currently underway.
D. Chemical Dehairing
    The effects of post-exsanguination (post-bleeding) dehairing on the 
microbial load and visual cleanliness of beef carcasses has been 
studied by Schnell et al., 1995. Ten grain-fed steers/heifers were 
slaughtered and 

[[Page 49561]]
dressed without dehairing. The carcasses of these animals were 
evaluated for bacterial contamination and visual defects (hair and 
specks) and for weight of trimmings made to meet ``zero tolerance.'' 
Overall, no difference was reported in aerobic plate counts, total 
coliform counts, and E. coli counts between samples from dehaired 
cattle and those from conventionally-slaughtered cattle. The lack of 
difference in bacterial counts was thought to be due to contamination 
in the facility from aerosols, and from people and equipment 
contaminated by conventionally-slaughtered cattle. An interaction was 
noted, however, between treatment and carcass sampling location. E. 
coli counts were lower in samples taken from rounds of dehaired 
carcasses than in samples from rounds of conventionally-slaughtered 
carcasses. The converse was found for samples from briskets, where 
higher counts were thought to be due to the additional handling of 
dehaired carcasses, i.e., the necessity of cutting the hide to assist 
in removal of hides that had become soapy and slippery during the 
dehairing process.
    The investigators stated the opinion that the microbiological 
status of carcasses from dehaired animals should improve in facilities 
designed to produce only dehaired carcasses. Dehaired carcasses had 
fewer visible specks and fewer total carcass defects before trimming 
(but not after trimming) than did conventionally-skinned carcasses. The 
average amount of trimmings removed from conventional carcasses to meet 
the ``zero tolerance'' specification was almost double (2.7 versus 1.4 
kg) that from dehaired carcasses.
    Additional tests, conducted in support of an industry petition 
(Monfort, 1995), compared the reduction of bacteria from hide to 
dehaired hide immediately after the dehairing process. These tests 
found a 99% reduction in total plate counts.

VI. The Conference

    FSIS is committed to ensuring that the most effective means 
available are used to achieve the zero tolerance standard for fecal, 
ingesta, and milk contamination of beef carcasses. The Agency's goals 
are to protect consumers from harmful contamination and thus reduce 
their risk of contracting foodborne illnesses. Given the importance of 
these goals, determining the most effective means of implementing the 
zero tolerance performance standard is one of FSIS's highest 
priorities. FSIS will act on the basis of sound scientific evidence, 
discussed in an open public process, to improve the safety of beef 
products through effective removal of fecal and associated microbial 
contamination.
    Accordingly, FSIS is hosting a conference to review the scientific 
and technical data and associated public policy issues involved in 
achieving the zero tolerance standard and improving beef carcass 
microbial safety. The conference will consist of two sessions on 
consecutive days. At the first session, participants will discuss 
available scientific and technical data comparing the efficacy of 
various methods for decontaminating beef carcass surfaces, focusing on 
the research summarized above. Participants are invited to make 15-
minute presentations during this first session and are requested to 
submit to FSIS, in advance, brief statements describing the general 
topics of their presentations (see ADDRESSES above). A panel of 
government scientists and managers will participate in this session and 
facilitate the discussion; the panel will be moderated by Ms. Patricia 
F. Stolfa, Acting Deputy Administrator, Science and Technology, FSIS. 
An opportunity will be provided for open discussion of scientific 
issues among all participants. Possible scientific and technical 
questions for discussion are:
    1. Do the studies offered to support the various decontamination 
alternatives conform to appropriate scientific standards?
    2. Are key results from individual studies reproducible and have 
they been replicated in other experiments?
    3. How effective is any specific treatment against microbial 
pathogens, and against E. coli 0157:H7 in particular?
    4. Is a specific treatment bactericidal or bacteristatic?
    5. Has a treatment been studied under plant conditions?
    6. What are the most effective locations for treatment on the 
carcass and on the slaughter line?
    7. If water is used, in what amounts? Can water be conserved or 
reused?
    8. Is there any threat to workers or the environment from residual 
treatment fluids, chemical waste, or biological hazards?
    9. Does a proposed treatment create an insanitary condition?
    10. Does a proposed treatment spread contamination on a carcass or 
spread contamination from carcass to carcass?
    11. Can - and should - a treatment be combined with other 
treatments? What would be the optimum combination?
    12. Does a proposed treatment interfere with current inspection 
procedures?
    13. When all the relevant studies are considered, does a 
discernible trend emerge supporting a policy choice?
    During the second session, participants will discuss the public 
policy issues surrounding beef carcass decontamination. This session 
will be moderated by Thomas J. Billy, Associate Administrator, FSIS, 
and Dr. Craig Reed, Deputy Administrator, Inspection Operations, FSIS. 
Possible policy questions for discussion are:
    1. What criteria should be used to decide that an alternative 
approach meets the zero tolerance performance standard for visible 
fecal contamination and associated microbial contaminants?
    2. What amount and quality of scientific data should be required in 
order to change current policy?
    3. Are alternative approaches equally feasible for all 
establishments that may want to use them?
    4. Should FSIS prescribe exactly how fecal contamination may be 
removed or should there be an organoleptic and microbial performance 
standard that companies can achieve as they see fit?
    5. What techniques should the FSIS inspection force use to verify 
that an alternative approach is functioning effectively?
    6. Should preventive measures be made part of this policy decision?
    7. What approaches to achieving the zero tolerance performance 
standard are consistent with a HACCP approach to process control? 
Conference Registration
    FSIS is requesting that persons planning to attend the conference 
preregister. If you plan to attend, please contact Ms. Mary Gioglio at 
(202) 501-7138 to register. Registration will also be available on the 
days of the conference on a space-available basis.
    Also, if you require a sign language interpreter or other special 
accommodations, please contact Mary Gioglio at the number listed above.

    Done at Washington, DC on September 20, 1995.
Michael R. Taylor,
Acting Under Secretary for Food Safety.

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