Articles in this issue:
Irradiation has proven to be beneficial in controlling pathogens
that could otherwise threaten meat products, but Food Safety Consortium
researchers are careful to emphasize that it's not a stand-alone
way of battling all potential problems. There is continued need
for other controls, including production of healthy animals, sanitation
throughout both production and processing and proper cooking.
Irradiation can play an effective role in reduction of important
pathogens as demonstrated in research by Consortium investigators
at Iowa State University.
Producers and processors are looking for ways to accomplish long-term
preservation of pork products and for ways to reduce possible
contaminating pathogens to negligible levels. Irradiation can
effectively inactivate harmful bacteria, yeasts, mold spores,
parasite cysts, and parasite ova in and on meat. Researchers at
ISU have also sought to measure the effects of irradiating meat
to inactivate contaminating viruses. Researchers wanted to find
out if acceptable dosage levels of irradiation would inactivate
important types of viruses directly as well as whether irradiation
would sensitize viruses on meat so that lesser amounts of heat
would be needed to actually inactivate them.
"Our basic conclusions in the first study were that only
large enveloped viruses like Herpes viruses were sufficiently
affected by irradiation alone that contaminated meat would be
make safe," said Dr. George W. Beran, ISU distinguished professor
of microbiology, immunology, and preventive medicine. "In
the second study we found that irradiation of virus contaminated
meat only slightly increased the sensitivity of the viruses to
low levels of heat, again with larger enveloped viruses being
more susceptible. We found that in the range of viruses that the
large viruses were more easily hit by the irradiation and inactivated
than were the small viruses."
The herpes virus, a relatively large enveloped virus, was readily
inactivated by irradiation and proved to be heat sensitive. "But
as we turned to smaller viruses, the heat inactivation was only
slightly increased in irradiated versus non-irradiated meat,"
Beran said.
The study showed, for example, that the pseudorabies virus (a
model for Herpes viruses) in pork was completely inactivated at
an irradiation dose of 5.27 kiloGrays or by 20 minutes of 50 degree
Celsius heat. But studies of Echo viruses showed that although
they were susceptible to being inactivated at slightly lower heating
levels after irradiation, the question of whether irradiation
could then be followed by lesser heating was not practically realized.
The study, conducted by Beran and ISU Food Safety Consortium investigators
Terry Proescholdt and E.C. Pirtle, found that treatment programs
for pork products, by a combination of irradiation and heat, reduce
foodborne hazards by some of the most important contaminating
viruses. But sanitary measures to prevent virus contamination
and cooking of the meat to inactive contaminating viruses are
still needed. Because most viruses which can cause human disease
through meat occur through human contamination, protection of
meat from viruses is important.
Although irradiation isn't a replacement for higher heating levels
when reducing virus levels, irradiation is effective in inactivating
both pathogenic and spoilage bacteria, and that extends the shelf
life of pork products. "Viruses do not affect shelf life,
because the viruses don't multiply.
They only stay viable," Beran said. "So from the standpoint
of shelf life, which is essentially bacterial, the irradiation
is definitely stronger."
The amount that pork products' shelf life is extended varies with
levels of irradiation, sometimes lengthening the life span from
one week to two weeks. But Beran cautioned that extended shelf
life should be considered only a secondary result of a process
that has safety as the main goal.
"It is more a consideration of having inactivated pathogenic
bacteria that would be real foodborne hazards than it is extending
shelf life," Beran said, adding that irradiation should not
be considered as a "magic bullet but as an extremely valuable
adjunct."
"We do not want to be accused of doing studies that would
lead to irradiation being a cover-up for a dirty product,"
Beran said. "Dirty product can be bacteria, which are the
easiest to measure. But dirty product can also mean contamination
with viruses or also with agricultural and industrial chemicals
or biological toxins which irradiation would not inactivate."
Beran said the sanitation of a product as it goes from production
through processing is very important. Irradiation is valuable
in eliminating pathogenic bacteria such as E. coli 0157:H7
in ground beef and Salmonella, Yersinia enterocolitica
and Campylo
Ïn pork.
One of food scientists' major concerns about meat contamination
is the reduction of pathogens acquired on the farm that animals
take with them to the packing plant. "We are not going to
eliminate them, but can we reduce them below the level that they
are a hazard?" Beran said.
"So Salmonella is a major approach for us here. That's
a major area of work right now and it is going to be increasing,"
Beran said. The question is if it is possible to raise swine in
practical ways that will bring about a sufficient reduction of
Salmonella and that will minimize the risk of Salmonella
coming in to the packing plant with the hogs and contaminating
their product.
"If there is one or two Salmonella per gram of meat
on our plates, that's going to be an absolutely minimum risk,"
Beran said. "But if there are 1,000 to 10,000 per gram, then
it's a major risk. Pathogens contaminate slaughter and processing
equipment, cutting boards, knives, hands, and other foods that
are not going to be cooked. We must pay attention to precautions
at every stage from farm to fork to protect our meat from disease-causing
hazards."
In the poultry processing plant of the future, the chicken carcasses
will be moved down the line and a knife-wielding robot will cut
out the meat in exactly the right place. This procedure will make
it possible to bypass the evisceration, or disembowelment, of
chicken carcasses and eliminate a source of contamination. It
will also eliminate the need for running the carcasses through
a chiller bath, another source for cross-contamination.
The future is closing in. A Food Safety Consortium research team
led by Joel Walker, a biological and agricultural engineering
professor at the University of Arkansas, is programming a computer-driven
robotic arm to make the precise movements for slicing into a carcass.
The robot can currently be directed manually to perform functions
down to movements of less than a millimeter. Translating those
movements into a computer program is the time-consuming part of
the project now under way.
A person who is manually directing the robot's movements can take
whatever amount of time necessary to cut the meat out of the chicken.
The computer program, however, must be developed so that the robot
will be able to perform the functions repeatedly for a line of
passing carcasses.
"One of the difficulties with this system is that as chickens
come around on a normal shackle line at a processing plant, they
would be moving continuously," Walker said. "Of course,
we've got to have them stop for awhile so we can operate on them.
... Obviously, with a processing plant sometimes running 30 birds
a minute, more or less, we're going to have to cut these birds
up in a few seconds."
The first step toward creating the automated system was development
of a holding platform that supports the carcass while the legs
are suspended in shackles. Meat was cut from the chickens in experiments
that measured the knife's manually guided linear and rotational
movements.
One of the hazards of cutting into non-eviscerated chickens is
the risk of cutting into the body cavity. "The closer you
cut to the body cavity the more danger there is of breaking that
body cavity and spilling the intestinal contents," Walker
said. And the main point of using robotics is to avoid eviscerating
the chicken before removing the meat.
"The object of this is to eliminate that contamination that
comes from the intestinal contents," Walker explained. "Normally,
when they eviscerate birds they drag the eviscera out of the bird.
It hangs down over the skin for a short time before the inspection
occurs. After the inspection it's removed and at that point may
leave contamination on the surface of the skin.
"With this process leaving all that intact, we've reduced
the likelihood that skin contamination will occur. But at the
same time in doing that process we've got to be very careful not
to cut into the body cavity and cause the same kind of spillage.
Making the cuts in the precise location is important."
Experiments on the birds using manual operation of the robot resulted
in varied sizes of body cavity openings. Walker said the use of
precise robotics equipment would provide more consistent results
and reduce the amount of the body cavity opening. Also, a higher
level of harvest of breast meat is expected as the mechanical
system is improved and more precise cutting is developed.
Mechanical meat stripping still has limitations. Experiments showed
that thighs and wings were not always separated precisely at bone
joints; tender meat was not readily separated from the rest of
the breast meat, and some meat remained on the carcass, particularly
on the back side. Measurement of the birds' size before cutting
begins should allow better control of knife motions.
When chickens are placed on the shackle line in preparation for
cutting, the robot program will have to be modified according
to the size and classification of each bird. "We don't know
how many classifications we'll need to make in order for that
to work," Walker said. Cuts on large birds will need to be
plotted into a computer program differently than those for a small
bird.
The robot controller can weigh the birds, and that may make it
possible to accommodate the various bird sizes. "The robot
can collect that information and feed that onto the program,"
Walker said. "The program would automatically modify itself."
So an approaching line of 3-pound birds would prompt the computer
to program the robot to make incisions appropriate for a bird
of that size.
Three computers combine to make this system work. The robot is
operated on a portable hand-held computer attached to the main
box from which the robot's motions are calculated. Another computer
transmits that data and actually controls the robot's movements.
A third computer collects data on force, temperature and other
types of motion sensing, and that information can be transferred
on disk to office computers where engineers measure and plot robot
movements.
"We can actually write programs using simulation systems
in the office and bring those (to the research lab), plug them
in on disk and have the robot move according to those directions,"
Walker said.
The hand-held computer has a red panic button that will shut down
the entire operation if necessary. It also has a key to control
the robot's speed.
Other possibilities exist for the holding platform and shackle
line. "We don't have that holding platform mechanized yet,"
Walker said. "This robot controller actually has the ability
to control more things than the robot itself. We could put a motor
with relays or whatever mechanism ... on that holding platform
so that as those chickens come by we can use those mechanisms
under the control of the robot's system to grab onto that chicken
and hold it while we're cutting it up."
The primary benefit of this system remains food safety. Researchers
are continuing to evaluate microbial contamination from the mechanical
meat stripping. The goal is to establish a system in which automated
meat stripping combined with carcass spraying will ensure that
clean carcasses stay clean.
Elimination of the evisceration process would have other impacts,
such as reduction of water and energy usage. And as is often the
case with new technological developments, the use of labor will
be affected.
The exact effect on the labor force is still uncertain without
knowing how mechanizing of the holding platform will work, Walker
said. Some jobs will be created as personnel will be required
to monitor and operate the robots.
"It may work out that this can reduce some of the labor-intensive
operation," Walker said. "It can reduce some of the
work-related injuries from repetitive motions of cutting up. It
could create more high-tech jobs."
As the Food Safety Consortium faces its eighth anniversary, I
am proud of its accomplishments and proud to be associated with
the organization as its coordinator and chairman of its steering
committee. L.B. (Bernie) Daniels, who formerly held those positions,
reurned to full-time faculty status in animal sciences on Jan.
1. In my role at the University of Arkansas as dean of the Dale
Bumpers College of Agricultural, Food and Life Sciences and associate
vice president for agriculture, I have agreed to succeed Dr. Daniels
in his positions with the Consortium.
Dr. Daniels deserves our thanks for his tireless service to the
Consortium. He has been a major player in the Consortium's operations
since he worked on its founding with Sen. Dale Bumpers several
years ago. His colleagues on the Consortium's Technical Executive
Committee -- George Beran of Iowa State University, Curtis Kastner
of Kansas State University and Frank Flora of the USDA Cooperative
State Research, Education and Extension Service in Washington
-- have offered their commendations to Dr. Daniels for a job well
done.
The Food Safety Consortium has a track record of accomplishment
and a level of recognition that few people likely expected it
to achieve when it began. The credit goes to the people who have
guided its progress as it set out to accomplish its congressionally
mandated mission: to develop technology for rapid identification
of infectious agents and toxins; to develop a statistical framework
necessary to evaluate the potential health risks; to determine
the most effective intervention points to control microbiological
or chemical hazards, and to develop risk-monitoring techniques
to detect potential hazards in the distribution chain.
The people who have shared the responsibilities for accomplishing
these tasks over the years have been the principal investigators
and their support personnel at the three universities who conduct
the research that is the heart of the Consortium's activities.
The steering committee -- comprised of representatives of the
three universities, the USDA and the beef, pork and poultry industries
-- has carefully reviewed the Consortium's overall activities
to ensure that the congressional mandate is met each year.
We have reason to be very proud of our colleagues' fine work in
food safety research. I am looking forward to working with them
as the Consortium continues to build on its excellent record.
Disease-causing food pathogens must be found before they can be
destroyed. Researchers at Kansas State University have found a
way to stimulate the growth of pathogens and have obtained a U.S.
government patent on the process.
Daniel Fung, a Food Safety Consortium investigator and professor
of animal sciences and industry at KSU, developed the process
called "Enzymatic Method for Acceleration of Comestible Products."
It was patented in January.
Fung is an authority in microbiological rapid methods, the area
of research that seeks to find pathogenic bacteria in food within
several hours of testing so food processors can know the quality
of their product and determine what to do if pathogens are found.
Fung's research team found that Oxyrase, a membrane fraction of
the E. coli bacteria, can stimulate the growth of food
pathogens such as Listeria monocytogenes, Campylobacter and
E. coli 0157:H7 in liquid broths.
Kooranee Tuitemwong of the KSU research team showed that Oxyrase
and food grade membrane fragments can stimulate the growth of
starter cultures, resulting in faster production of yogurt, buttermilk,
bread, wine, beer and summer sausage in laboratory scale experiments.
The process can save the amount of time food processors spend
on fermentation. "If you ferment faster, you kill pathogens
faster," Fung said.
"We started the research to find out how fast we can stimulate
the growth of the pathogens to detect them," Fung said. "Now
we find out that these starter cultures --- the 'good guys' ---
with the help of enzymes grow faster so we can kill the 'bad guys'
faster."
If it turns out there are no pathogens in the product, the use
of Oxyrase and food grade membranes will make it possible for
fermentation to take place faster, saving time and money for processors.
"In large-scale fermentation --- talk about money for heating
and cooling," Fung said.
Recent government approval of steam pasteurization as a way of
removing bacterial contamination from beef carcasses came as welcome
news to Food Safety Consortium researchers at Kansas State University.
KSU investigators conducted several trials testing the procedure
at the campus food microbiology and meat processing facilities
and determined it was an effective decontamination treatment,
especially when used with washing, trimming and hot water/steam
vacuum spot cleaning to remove visible contamination.
The U.S. Department of Agriculture's Food Safety and Inspection
Service approved the process in December. Steam pasteurization
was jointly developed by Frigoscandia Food Process Systems Inc.
of Bellevue, Wash., along with Cargill Meat Sector of Minneapolis
and Excel Corp. of Wichita, Kan. KSU assisted in establishing
proper operating parameters based on bacterial kills and carcass
color followed by in-plant commercial trials. Excel already has
a steam pasteurization unit installed for use at its meat packing
unit in Sterling, Colo., and plans to place units in its remaining
plants in the U.S., Canada and Australia this year. Other large
meat packers have indicated that they will install pasteurization
equipment shortly, with over 60 units reserved on a waiting list.
"Steam pasteurization is designed to be used only after carcasses
have been trimmed or vacuum spot-cleaned to meet current USDA
zero tolerance criteria for physical contamination," explained
Dr. Randy Phebus, a Food Safety Consortium researcher and KSU
assistant professor of food microbiology, who led the microbiological
evaluations of the system.
"Steam pasteurization was not developed to replace current
carcass decontamination methods, but to be used as a final whole
carcass antimicrobial treatment immediately prior to carcasses
entering the cooler," Phebus said.
USDA, as defined in a recent Federal Register notice, is
going to open up other technologies, "such as rinsing technologies,
steam pasteurization and vacuum spot cleaning in what's called
a multiple hurdle approach so that you have a series of steps
in the process that reduce microbiological contamination,"
said Dr. Jim Marsden, a Consortium researcher and KSU professor
of animal sciences and industry. "So the carcass looks clean
and it gets cleaner as it goes through each step in the process."
Once a carcass is cleaned of visible contamination, steam pasteurization
comes into play for elimination of the invisible pathogenic bacteria.
"It certainly works better when you present a clean carcass
into the steam pasteurization system," Marsden said.
The E. coli 0157:H7 bacteria can enter meat products during
the slaughter and evisceration process from intestinal contents,
milk or filth from hide removal.
"Trimming and vacuum spot cleaning are effective in removing
visible contamination from small localized areas of the carcass,"
Phebus said. "Steam pasteurization which utilizes a hot water
vapor offers the advantage of uniformly condensing over every
square millimeter of that carcass, thereby killing invisible bacteria
even where the carcass appears visibly clean. Even washing and
the organic acid sprays don't provide that type of coverage. We're
eliminating almost all bacteria with the exception of a few sporeformers
and using only environmentally friendly water vapor."
The steam condenses on the carcass at temperatures of about 200
degrees Fahrenheit since the pasteurization chamber is slightly
over atmospheric pressure. "The meat surface almost instantaneously
reaches this temperature, effectively kil,teria," Phebus
said. "I haven't met too many food-related bacteria
that can withstand these high temperatures."
Steam pasteurization is the final step in the process of cleaning
carcasses that are first cleared of visible contamination. Marsden
does not believe the procedure will become mandatory because of
religious and ethnic concerns in the preparation of some foods.
For example, steam is not permitted on carcasses of kosher products.
But USDA's consideration of E. coli 0157:H7 as an adulterant
in raw meats, along with consumer pressures for safe meat products,
will probably drive the increasing popularity of steam pasteurization,
Phebus said.
"If you come off the slaughter floor free of E. coli 0157:H7,
because you've steam pasteurized it, it's very unlikely to recontaminate
the carcass with that particular pathogen during further processing
if proper sanitary procedures are in place and followed,"
Marsden said. "It's not one that's likely to be carried around
by people or to be environmentally present in the fabrication
area of the plant. So I think that once steam pasteurization,
in conjunction with other decontamination processes, is implemented
across the industry that the problem of E. coli 0157:H7
in ground beef are going to be tremendously reduced if not eliminated."
Arcobacter bacteria in swine and the susceptibility of piglets
to it is emerging as a potential concern among scientists. Food
Safety Consortium researchers at the National Animal Disease Center
in Ames, Iowa, are looking for more information about the role
of livestock as carriers of foodborne pathogens and are evaluating
management practices to reduce the pathogens.
Elsa Murano, now a researcher at Texas A&M University; Cliff
Collins, who was a graduate student at Iowa State University,
and Irene Wesley, a principal investigator for the Consortium
and a scientist at NADC, surveyed five ground pork plants for
the presence of Arcobacter and found results testing positive
in ranges from zero to 90 percent among recovered samples. Differences
in plant hygiene or swine-rearing practices could account for
the differences in the incidence rate, the research team conclude
Researchers examined neonatal piglets that had been experimentally
infected and determined that Arcobacter butzleri species
to be pathogenic. Earlier studies had shown that the pathogenic
Campylobacter jejuni and Helicobacter pylori bacteria
readily colonized neonatal piglets as did Arcobacter butzleri.
Scientists have been studying the advantages of protecting pigs
from pathogenic infection soon after birth. Another aspect of
the NADC effort at detecting potential foodborne pathogens in
livestock is focusing on management practices with young pigs.
This study is examining the practice of segregated early weaning
of pigs.
"We wished to determine if the prevalence (Campylobacter
jejuni, Campylobacter coli, Arcobacter and Listeria monocytogenes)
was lower in pigs raised by segregated early weaning than with
on-farm cohorts," Wesley said. At three weeks of age, the
piglets entered the segregated nursery. They were sampled upon
entering the nursery, upon exiting four or five weeks later, and
when they reached market weight.
Preliminary data from the study indicated that the piglets were
positive for Campylobacter even though they had been administered
antibiotics as they entered the nursery and had received a diet
of medicated feed. But the difference in incidence was slight
between the segregated pigs, with 38 percent testing positive,
and the pigs that remained on the farm, of which 41 percent tested
positive.
Arcobacter, however, was more prevalent in this experiment
among the segregated pigs. The segregated herds registered 84
percent testing positive while only 24 percent among the on farm
pigs. No incidents of Listeria monocytogenes were found
in either the segregated or on-farm herds.
The study showed that "a management system which reduces
the prevalence of one pathogen may not guarantee a decline in
all potential foodborne agents," Wesley said. The NADC study
will continue with scientists conducting a second evaluation on
the impact of segregation on reducing Campylobacter and
Arcobacter in pigs. The researchers are also participating
in a U.S. Department of Agriculture National Animal Health Monitoring
Survey in which they will look for Campylobacter jejuni and
Yersinia.
Karen Harmon, who is working at NADC while a postdoctoral fellow
funded by the ISU Food Safety Consortium, developed a multiplex
polymerase chain reaction (PCR) to distinguish potential zoonotic
foodborne pathogens. Harmon designed a PCR test to differentiate
Arcobacter from other closely related bacteria.
Listeria monocytogenes has caused major epidemics associated
with consumption of cheese, coleslaw, French pate and pickled
pork tongues. "Zero tolerance" regulations exist against
allowing processing of foods with L. monocytogenes. A product
can be recalled if L . monocytogenes is found in ready-to-eat
foods. Imported products are banned if found positive for L.
monocytogenes. Harmon has designed a PCR test to distinguish
L. monocytogenes from other Listeria species.
The bacterium Campylobacter jejuni has been recently linked
to Guillain-Barre syndrome. In collaboration with Food Safety
Consortium researcher Debra Winters at the University of Arkansas,
Harmon constructed a PCR test to differentiate Campylobacter
jejuni from Campylobacter coli. These microbes are
difficult to grow in the laboratory and there are few tests to
separate them.
Researchers with the Food Safety Consortium assembled for their
annual meeting recently in Kansas City and reviewed ways to reduce
foodborne pathogens through improved methods of detection and
elimination. The Consortium's members from the University of Arkansas,
Iowa State University and Kansas State University met with representatives
of industry and government.
Thirty papers were presented by researchers reporting on the progress
of their projects. University of Arkansas researcher Amy Waldroup
reported on the results of using trisodium phosphate (TSP) to
reduce microorganisms in commercial poultry processing plants.
Only one U.S. processor has adopted the use of TSP for routine
treatment of its products. Waldroup's report revealed that three
retail surveys suggested that turkey carcasses or leg quarters
treated with TSP did not provide the consumer with a microbiologically
safer product, and recovery of Listeria was actually enhanced
by TSP treatment. Waldroup noted that poultry companies should
not rely solely on TSP to control Salmonella or any other
pathogen.
An Arkansas research team led by Michael F. Slavik and Debra K.
Winters has developed a polymerase chain reaction (PCR) for Campylobacter
jejuni, a bacterium that is a major cause of human acute gastroenteritis.
The assay can be used to detect C. jejuni on chicken carcasses.
This immunoassay, which is specific for C. jejuni, could
be used for reliable identification and diagnosis of C. jejuni
gastroenteritis.
"Rapid detection of low numbers of C. jejuni directly
from contaminated foods would be beneficial not only in reducing
the time in which appropriate measures could be taken to remove
such food from consumers, but also in reducing the time of diagnosis
and treatment," Winters said.
A study by another team led by Slavik and J.W. Kim found that
eggs washed in processing plants with alkaline chemicals were
30 to 70 times more porous than eggs washed with other chemicals.
The team found that chemicals added in washwater could cause damage
to the egg shell, which could allow bacterial penetration. The
results showed that commercial detergents based on strong alkaline
chemicals removed most of the cuticle layer, making the eggs more
porous and possibly more susceptible to post-wash bacterial penetration.
The team suggested that egg processing plants might consider the
use of washes other than high alkaline detergents in egg washing.
Joel Walker of Arkansas reported on his team's work on a robotic
system to remove meat from noneviscerated chicken carcasses. The
system, which is still under development, would eliminate or reduce
contamination of chicken from spilled contents of the body cavity.
The project is focusing on development of methods to hold the
carcass in place, the knife motions required to remove the meat
and the measure of benefits in reducing microbial contamination.
Walker's team is also examining the results of tests conducted
with a research oven to study how the cooking process affects
the destruction of microbes, heat transfer and the effects of
air impingement and moisture within the oven.
Iowa State researchers found that treatment of pork products with
heat after irradiation may reduce contamination and extend their
shelf life. George W. Beran told the annual meeting about experiments
in which ground 80-percent lean pork was contaminated with four
viruses and treated with different levels and times of heat after
being exposed to measured doses of irradiation. The question was
whether the absorbed irradiation would sensitize a virus so that
a lesser amount of heat would be necessary to inactivate the virus.
Beran also reported on progress being made in reducing pathogens
in meat. Pathogenic bacterial contaminants "must be prevented
or removed during slaughter operations," Beran said. "The
HACCP (Hazard Analysis and Critical Control Points) approach will
be different from the traditional inspection system."
Essential components of prevention programs, Beran said, include
the following: keeping all feeds free of Salmonella and
protected from contamination, sanitation in production units,
control of personnel working in the production units, prevention
of contact between production units or animals with dogs, cats,
rodents, birds and insects; prevention of animals from exposure
to infectious and parasitic diseases, and maximum control of stress.
"A limited number of studies evaluating costs and benefits
of approaches to prevent hazards at production level have been
reported, particularly in Salmonella control programs in
Europe, and studies in progress at Iowa State University are assessing
effectivity of multisite, age-segregated rearing in breaking endemic
cycles of Salmonella infections," Beran said.
Michael Grant of Iowa State reported on development of a new membrane
filtration medium (in ColiBlue) for simultaneous detection and
differentiation of total coliforms and Escherichia coli .
Evaluated so far for application in water testing, further studies
are identifying sensitivity in cultures on pork. This is important
in consideration of monitoring meat for E. coli contamination.
Kansas State researchers discussed their work in steam pasteurization
as a way of decontaminating freshly slaughtered beef tissue. The
process has been shown to be effective in reducing high pathogenic
bacterial populations. "We are on the verge of a revolution
in improving the microbiological safety and quality of meats,"
KSU researcher Randy Phebus said.
Research showed that the most effective treatments would involve
trimming and/or spot steam vacuuming of visible contamination
followed by application of steam to the meat surface. Phebus said
that in addition to improving the efficiency of pathogen removal,
the steam pasteurization process would likely enhance the shelf
life of further processed meat portions.
Melvin Hunt of Kansas State explained the results of another study
of the effects of supplementing the diets of cattle with Vitamin
E. The vitamin is administered to give ground beef patties up
to a five-day extension of retail display life. Hunt said Vitamin
E does not affect the internal cooked color or expressible juice
of patties nor does it prevent premature browning of patties or
cause persistent redness. Premature browning can create a potential
safety hazard because it gives patties the appearance of having
been cooked thoroughly when in fact any pathogens in the patty
might still be viable.
Irradiation of boneless pork chops was found to have no effects
or very limited effects on quality, Don Kropf of Kansas State
said. He presented the results of a study of the effects of irradiation
at three low-dose levels on flavor, aroma, color and product life
of chilled and frozen pork chops in vacuum and aerobic packaging.
An investigation of how children under 4 years old acquire Salmonella
infections showed that environmental contamination from a
common unidentified source is likely to be an important factor
contributing to children's acquisition of the infection. According
to the study by Gordon Schutze and Russell Kirby of Arkansas Children's
Hospital in Little Rock, food did not appear to play a major role
in development of the infections. The study was conducted over
two years on 90 children to identify the risk factors that led
to the infections.
Ever since a strain of bacteria was linked to several cases
of food poisoning in the Northwest in 1993, food safety has been
of increasing concern to consumers. But detecting this bacteria,
E. coli 0157:H7, is difficult.
Scientists at Iowa State University and two other land grant universities
have turned to biotechnology in the search for a way to detect
this dangerous bacteria.
A grant from the USDA is funding the research at ISU. One of the
projects in the grant is being conducted by Loren Will, along
with Greg Phillips, both in the Department of Microbiology, Immunology
and Preventive Medicine.
The researchers use a molecular probe to find E. coli 0157:H7
genetic material. Then with a process called polymerase chain
reaction (PCR), these genetic markers are multiplied for easier
detection.
Will said the PCR technique allows the scientists to generate
enough DNA material to identify E. coli. "We're not
actually coming up with live cells," he said. "Instead,
we're able to simply identify the bacteria by a pattern that forms
as the material is drawn across a gel."
Before the use of PCR, the only way for researchers to identify
bacteria was to grow them in a culture dish, run biochemical tests
on isolated colonies, and view them under a microscope. Will said
the PCR technique is a more precise method, and the next step
is to "speed up the process and make sure it works accurately
every time."
The ISU research has only been done on ground pork. Will's team
will continue to use the PCR technique to look for E. coli
markers in a variety of places.
"We'll be testing samples of soil, water, and slaughtered
animals from both farms and processors," he said. "We're
essentially trying to detect this bacteria anywhere it could be,
from the farm to the fork."
The USDA is working on a new system of meat inspection called
Hazard Analysis and Critical Control Points (HACCP). The idea
is to prevent bacterial contamination at all points in the food
chain. It would be incorporated with the current system of using
sight, smell and touch to
detect contamination.
Will said he believes using PCR to detect the E. coli bacteria
could work in concert with HACCP. "This process could take
about four hours to see if the bacteria is present," he said.
"Using a culturing method, it can take 36 to 48 hours to
do the same thing." With that kind of lag time between slaughter
and detection, Will said the meat would already be moving from
the processor to the consumer before any problems could be found.
As part of the three-state Food Safety Consortium, research on
PCR to detect E. coli bacteria is also under way at Kansas
State University on beef and at the University of Arkansas on
poultry.
"What we're doing is meaningful," Will said. "But
this is only one of many tools being looked at to improve food
safety. We're one cog in the wheel of science in this effort."
When poultry reaches the processing plant, some birds are condemned
during the inspections for a variety of reasons. By determining
what factors contribute to those condemnations, poultry processors
can reduce the number of carcasses condemned and improve the overall
quality of the processed product.
A Food Safety Consortium research project helped one poultry company
take advantage of readily available statistics to improve its
condemnation record. Dr. Amy Waldroup, a University of Arkansas
poultry science professor, reviewed the material in agricultural
survey data and showed the company where its weak spots affected
the health of its flock. Since then, the company has significantly
reduced the percentage of carcasses condemned at the plant.
Poultry companies regularly obtain data from agricultural survey
companies that monitor the efficiency of the companies' live production
and the quality of their processed carcasses. Statistical reports
on the companies are prepared and distributed to them, ranking
them according to their performance. A particular company can
see what its numbers are and can see how its competitors are doing,
although the statistics don't identify the competitors by name.
So a poultry company's executives would know how its statistics
compare to the top company on the list, although they wouldn't
know who has the top ranking.
The statistics provide data on the number of condemnations experienced
by poultry companies, but they don't tell why the numbers are
at a certain level. "Is it because you have an inspector
who's more strict than others?" Waldroup said. "Do you
have poor bird health? Do you have poor nutrition?"
The poultry company that the UA researchers investigated is a
small one. Its level of condemnations was higher than several
of its competitors. "We wanted to try to help them look at
this data in a new way to see if they could determine why they
were falling short all the time," Waldroup said.
Researchers conducted a case study to determine whether any live
production factors were related to the percentage of condemnations
in the company's processing plants over two years. The client
company's figures were compared to the corresponding numbers for
the top-ranked companies. Then the production factors were correlated
to the condemnation figures. For example, did the calorie content
of the birds' diet correlate with the condemnation levels among
the companies? Other factors evaluated were the number of days
a chicken house sat empty between flocks, the rate of early mortality,
overall mortality and stocking density.
"What we determined was that a lot of these factors in the
processing plant had to do with bird health," Waldroup said.
"Nutrition wasn't a factor. All the factors that had to do
with bird health correlated with processing plant problems."
With that information, the company made changes to improve flock
health and carcass quality. The changes included improved hatchery
sanitation, increasing the number of days between flocks occupying
the chicken houses, and a reduction in stocking density.
Poultry companies have generally not correlated agricultural survey
data figures to determine the source of their problems. Industry
representatives who listened to a presentation on the Arkansas
research process at the annual Poultry Science Association meeting
in Canada expressed interest in the procedure, Waldroup said.
They wanted to know how to implement it so they could evaluate
their companies' performance.
The chemical compound trisodium phosphate (TSP), although approved
by the government for use as a processing aid for poultry, doesn't
provide consumers with a safer product, a Food Safety Consortium
research team has found. The researchers, based at the University
of Arkansas, concluded that poultry companies should not rely
solely on TSP treatments to control pathogens.
TSP is a substance also used in detergents and in making water
softeners and paper. A process for treating turkeys with TSP has
been patented. The Arkansas researchers analyzed commercial turkey
carcasses that had been treated with TSP and compared them with
untreated carcasses. Pathogens were not virtually eliminated,
the researchers determined.
"Some could argue that TSP treatment is just one hurdle or
step in a HACCP-based program," the team's research report
said. "However, if a hurdle is not effective, why include
it?" (HACCP programs are science-based approaches to identifying
and controlling critical points in food production that can affect
food safety. The system is being implemented in meat and poultry
plants in addition to the current inspection system to provide
more check points to prevent microbiological contamination.)
Dr. Amy Waldroup, a poultry science professor at Arkansas and
a principal investigator for the Consortium, said the research
showed there wasn't any benefit in using TSP in poultry processing.
Waldroup objected to any characterization of the process as virtually
eliminating pathogens. "It makes the consumer think (pathogens)
are almost all gone, and they're not," she said. It would
be more accurate if a TSP marketer claimed that the ingredient
was being used in an effort to control pathogenic organisms, she
said.
Currently, only one poultry processor has adopted TSP for routine
treatment of its products although several companies have experimented
with its use. "If this new technology significantly improves
the safety of raw poultry, why hasn't the practice been adopted
by a major portion of the industry?" the team's report asked.
In three separate trials, the research team analyzed whole turkey
carcasses. In two trials the turkeys were purchased at retail
with those in one trial fresh and those in the other trial frozen.
In the third trial, the carcasses were obtained directly from
the processor. In each trial, carcasses had been treated with
TSP or were untreated. In the fourth trial, TSP-treated and untreated
turkey leg quarters were examined.
The trials showed mixed results as to the prevalence of pathogens
on the carcasses, but pathogens were present at various levels
in all cases.
The first trial showed that 65 percent of the untreated turkeys
and 10 percent of the TSP treated turkeys were contaminated with
Salmonella. Seventy-five percent of the TSP-treated carcasses
contained Listeria bacteria, although not the pathogenic
Listeria monocytogenes species.
In the second trial, 56 percent of the TSP-treated turkeys tested
positive for Salmonella contamination while 31 percent
of the untreated turkeys were contaminated. Eighty-eight percent
of the TSP-treated carcasses tested positive for Listeria;
of the Listeria isolates from the TSP-treated carcasses,
64 percent were identified as the pathogenic Listeria monocytogenes.
Results of the third trial --- using the turkey carcasses provided
by the processor --- were different than those in the first two
trials. The TSP treatment appeared to work. Only 5 percent of
TSP-treated carcasses were positive for Salmonella while
30 percent of the untreated carcasses were positive. Twenty percent
of the TSP-treated carcasses tested positive for Listeria although
none of the isolates were identified as Listeria monocytogenes.
Levels of the pathogens E. coli and Campylobacter jejuni
were reduced in these cases, although by very small amounts.
The researchers noted that it might appear that the carcasses
purchased at retail may have had higher levels of these pathogens
because retail storage allowed for the growth of the organisms.
But the scientists saidthat temperature abuse of the carcasses
could have occurred during transportation, distribution or retail
storage. That could account for the growth of E. coli, they
said, but it is unlikely that Campylobacter jejuni would
grow under those conditions.
Also, the TSP-treated carcasses in the third trial did not contain
necks or giblet but the untreated carcasses did contain these
items. The necks and giblets are usually more contaminated on
the surface, which could account for the reduced pathogen count
on the TSP-treated carcasses.
The fourth trial used turkey leg quarters because this was the
only TSP-treated product available at the retail location where
the products were purchased. The goal in this test was to determine
whether the first two trials offered results representative of
TSP-treated products, so only TSP-treated leg quarters were purchased.
These results showed the levels of aerobic plate count and the
pathogenic Staphylococcus aureus and Campylobacter jejuni
were higher than in the other three trials. Aerobic plate
counts indicated that the leg quarters would have been considered
spoiled. Thirty percent of the samples tested positive for Salmonella.
A contributing factor to these higher rates of contamination may
be the additional handling required. "They had to go through
a cut-up where they may have stayed longer at room temperature
so organisms like E. coli could have had a chance to grow,"
Waldroup said.
Reviewing the overall results, the team determined that recovery
of Listeria may be enhanced by treating poultry with TSP
and that levels of Staphylococcus aureus do not appear
to be affected by TSP.
Daniel Y.C. Fung of Kansas State received a grant from
the Organization for Economic Cooperation and Development based
in France to participate in research work on safety of meat, milk
and other animal products. Fung traveled throughout Europe and
presented papers at the Technical Institute of Olsztynie, Poland;
Agricultural University of Wroclaw, Poland; Ninth World Congress
of Food Science and Technology in Budapest, Hungary, and the Public
Health Department of the city of Budapest. He was also an invited
speaker at the Pasteur Institute in Paris. He presented a paper
on "Rapid Methods and Automation in Microbiology."
George W. Beran of Iowa State attended the United States
Animal Health Association meeting Oct. 30-Nov. 2 in Reno, Nev.
He is vice chair of the USAHA pseudorabies committee and a member
of the food safety, animal production food safety, feed safety
and pseudorabies program standards committees.
Beran also represented the American Veterinary Medical Association
in Washington in November at a USDA Food Safety and Inspection
Service meeting to finalize a new inspection system.
In October, Beran visited Premium Standard Farms in Princeton,
Mo., for collaborative research in swine Salmonellosis with
ISU graduate student Dave Baum.
Dermot Hayes, Jason Shogren and James Kliebenstein
of Iowa State published "Valuing Food Safety in Experimental
Auction Markets" in the February 1995 issue of the American
Journal of Agricultural Economics; "A Comparison of Preferences
for Pork Sandwiches Produced From Animals With and Without Somatotropin
Administration" in the Journal of Animal Science,
and "Consumer Response to Milk Produced by Cows Provided
Bovine Somatotropin" in the 1995 Dairy Report produced
by Iowa State University Extension. Kliebenstein was also
interviewed on "Consumer Response to Improved Food Safety"
on KICD Radio in Spencer, Iowa.
Dong Ahn of Iowa State, who recently joined the Food Safety
Consortium as a principal investigator, reported he has had 24
publications in refereed journals and 11 presentations in conferences
from 1987 to 1995.
Paula J. Fedorka-Cray of the National Animal Disease Center
in Ames, Iowa, co chaired the HACCP Symposium at the Conference
of Research Workers in Animal Diseases meeting in November.
Yanbin Li, Joel Walker, Michael Slavik and Hong Wang
of Arkansas published "Electrical Treatment of Poultry
Chiller Water to Destroy Campylobacter jejuni" in
the Journal of Food Protection.
H.M. Stahr of Iowa State has been issued a patent, "Volatilization
of Antimicrobial Drugs." The purpose is the elimination of
antimicrobials in feed to eliminate residues in tissues. The process
is for reusing chill water with ozonolysis sanitation with the
American Water Purification Co. The process has been accepted
by the USDA Food Safety and Inspection Service and the Food and
Drug Administration. Stahr has also been invited to present a
paper on "Reduction of Aflatoxin in Milk From Cows in China"
at the Rocky Mountain American Chemical Society meeting in Denver
in June. The Journal of Veterinary Diagnostic Investigation
has accepted Stahr's article on "The Improved Method for
Rumensin Analysis."
Nancy Brown of Iowa State published "Evaluation of
Microbial Hazards of Pork Products in Institutional Food Service
Settings" in two segments in successive issues of Dairy,
Food and Environmental Sanitation.
The U.S. Department of Agriculture has taken the first major
step toward implementing a rule on Hazard Analysis and Critical
Control Points (HACCP) inspection systems in meat and poultry
plants. The USDA Food Safety and Inspection Service in January
released regulatory reforms that are designed to lead to adoption
of a final rule on HACCP plans later this year.
HACCP programs are science-based preventive systems of food safety
controls implemented at key points in food processing.
"The changes are part of our comprehensive overhaul of the
nation's meat and poultry inspection system," said Michael
R. Taylor, USDA acting undersecretary for food safety. "The
reforms are intended to support the new food safety measures USDA
plans to adopt for all federally inspected meat and poultry plants."
As part of the regulatory reform effort, FSIS conducted a page-by-page
review of its existing rules. FSIS said it identified more than
400 pages of regulations, about three-fourths of the total, "as
candidates for elimination or change to make them simpler, less
burdensome or more performance-based."
* * *
The work of Food Safety Consortium researchers at the National
Animal Disease Center in Ames, Iowa, was featured in the February
edition of Agricultural Research, the monthly magazine
published by the USDA Agricultural Research Service. The article,
entitled "Keeping 'em Off the Farm," examined NADC's
efforts to combat foodborne diseases spread by pathogenic microorganisms.
The article covered NADC's work on several projects: weaning piglets
in a sanitized environment to prevent Salmonella outbreaks;
studying the relationship between stress and the presence of Salmonella
in pigs' feces; developing a polymerase chain reaction to
quickly detect Campylobacter, Listeria and Arcobacter;
learning about the link between dietary stress in cattle and
incidence of E. coli 0157:H7; detection of Listeria
monocytogenes in cattle; pasteurization methods for killing
Mycobacterium paratuberculosis in livestock, and development
of a polymerase chain reaction to detect Brucella in cattle.
* * *
The state of New York is beginning a public education campaign
this spring to prevent illness from the pathogenic E. coli
0157:H7 bacteria. The campaign will be aimed at the highest
risk groups: young children, the elderly and those with weakened
immune systems. Media events and public and private organizations
will be used to reach the public.
* * *
Three federal agencies that deal with food safety are working
together to collect data about diarrheal diseases, particularly
those caused by E. coli 0157:H7 bacteria. The USDA Food
Safety and Inspection Service, the Food and Drug Administration
and the Centers for Disease Control are gathering information
in northern California, Oregon, Minnesota, Connecticut and Atlanta.
The project will review the risk factors for diarrheal diseases
related to meat, poultry, dairy products, fruits, vegetables and
seafood.
* * *
The Food Safety Consortium now has a 3-by-6-foot color poster
with photos depicting research highlights at its three universities.
Three copies of the poster exist, one for each campus to display
as it wishes. The poster has been displayed at the USDA Food Safety
Conference in Washington and the American Farm Bureau Federation
convention in Reno, Nev. We hope to show it at other events as
they are held.
If you have comments or questions, contact us by U.S. mail at
the Food Safety Consortium, 110 Agriculture Building, University
of Arkansas, Fayetteville, AR 72701; by fax at 501-575-7531, or
by e-mail at dedmark@comp.uark.edu.