Articles in this issue:
Food processors know that meat must be heated to at least 160
degrees Fahrenheit at its innermost point to ensure that harmful
bacteria in the meat are killed. But to make certain they have
reached that internal temperature, processors may have to overcompensate
by turning on so much heat that it cooks the rest of the meat
more than necessary. It would be good to determine just when the
center of the thickest part of a piece of meat reaches the required
temperature. Food Safety Consortium researchers at the University
of Arkansas have found a way to do it --- they built their own
The oven was designed by a team led by Joel Walker, a principal investigator in the Consortium and a professor of biological and agricultural engineering. This group worked to accommodate needs prescribed by another principal investigator, Michael Johnson, a professor of food science
The oven was recently installed and will be used to analyze thermal penetration of meat products. Equipment testing over the coming months will be conducted by Jim Goff, a doctoral degree candidate and a senior graduate assistant in food science, and Jing Yan Luo, a master's degree candidate and a graduate assistant in biological and agricultural engineering.
The oven was assembled on the Fayetteville campus with parts acquired for about $5,000. "It would have cost $20,000 to $30,000 to buy a ready-made large commercial oven," Walker said. And if one had been purchased, researchers still would have had to manipulate its instrumentation to accomplish what they want, Walker said. The researchers can modify the custom-made oven and adjust its internal components for individual experiments.
The oven can be modified to change the temperature, the heat flow and the intensity level in evaluating how these factors affect the food quality while destroying potentially harmful microbes. Walker explained.
Eliminating bacteria in uniformly shaped meats such as hamburger patties does not pose the problem that processors potentially face with irregularly shaped meats such as chicken pieces. The research oven is designed to measure how quickly and at what point all the bacteria are killed in whole muscle foods such as chickens and their components made up of thick and thin portions.
Johnson explained that the researchers will be looking into the "heat-cook factor," which he described as the opposite of the wind-chill factor. They will review the effects of heat intensity on chicken as it progresses through the cooking process.
With irregularly shaped meat products such as chickens, "what we want to do is get the minimum time to get a good quality product that's properly cooked, but not overcook it," Johnson said. Overcooking the product will still ensure that the bacteria are killed, but then its marketability is threatened.
"You are drying out your product," Johnson said of the results of overcooking. "You lose moisture, juiciness, possibly tenderness. You want to find the amount of time that will kill all bacteria while giving an optimal quality product."
Or, as Goff described, "get it so the thickest part of it is done while the thinnest part of it is still maximum quality."
Bacteria can enter chicken tissue during the marinating process. Many whole muscle products are marinated to enhance the flavor, juiciness and texture. Marinating lessens the loss of water during cooking and maximizes the yield. Chicken pieces are placed in a vacuum tumbler, a sealed chamber in which the air is removed from the product and liquid marinate is forced into the meat.
The bacteria that enter chicken via the marinating process can grow exponentially. They can quickly multiply over 1 to 2 minutes, accumulating into the millions. The good news is that when heat begins killing them, they die in large numbers at an equally quick rate. But, Johnson explained, "there's a potential for the last part of the (surviving bacterial) population to be more resistant and not die off at the same fast rate as the initial part of the population." The goal is to make sure those last survivors are finally killed.
The last stand of the surviving bacteria is aided partly by the irregular shape and varying thickness of whole muscle products. That wouldn't be a problem in killing bacteria in a liquid product such as milk because the heat can be distributed more evenly during the pasteurization process. The experimental oven is designed to help scientists develop a process for decontaminating whole muscle products on a time and temperature basis similar to pasteurization.
The oven is designed to determine what it takes to destroy all the bacteria and how long it takes to do it. For experimental purposes, an incision is made into a chicken breast and beads containing Listeria bacteria are laid into the thickest and coldest portion. A non-pathogenic derivative of Listeria is used instead of the pathogenic Listeria monocytogenes bacteria that often invade meat products. But the non-pathogenic derivative has the same heat-resistant characteristics as Listeria monocytogenes.
To measure the impact of the heat, the researchers place temperature sensors into the meat as it proceeds down the oven's conveyor belt, creating a running temperature profile. The thermocouples are hooked into a computer which records the temperatures in specific parts of the chicken during different times in the cooking process. After that part of the experiment is complete, the temperature profile history is correlated with the bacteria casualty rate. The question at this point is are there any survivors.
Johnson noted the researchers know how many bacteria were inserted into the chicken. "We can come back to where these beads were. They'll still be intact. We'll then ask if there are any viable bacteria left in those beads in the cooked chicken. We'll open the chicken back up and pull it out. ... If things are behaving properly at a certain amount of temperature, we ought to get down to where we have thousands of grams of chicken, and there might be a tiny amount of viability left in a tiny amount of bacteria that you can't even count."
Under such circumstances, it is likely that there won't be any surviving bacteria in the thin part but there may still be a few in the thick part. Zero tolerance in a 25-gram sample per cooked product is still the operative standard under USDA rules because some people with low tolerance levels for disease are susceptible to food poisoning from small amounts of bacteria.
To make sure all the bacteria have been killed --- right down to the hardiest resisters deep in the interior of the meat --- researchers want to find out exactly how long the heat needs to be on at what temperature and how much humidity to allow during the cooking. Moisture accelerates heat transfer and the experimental oven can control the humidity level in addition to the temperature during cooking.
"We want to optimize the cooking in the oven and the temperature and time so we get the maximum heat transfer in the cold part of the meat and optimize that time that we get it fully cooked to the prescribed temperature and at the same time destroy the bacteria that could be there," Johnson said. As a safety margin, scientists aim at more bacteria than they believe are probably there, thus increasing the chances of killing any resistant bacteria.
"That's what we want," Johnson said. "Lots of kill."
The Consortium looks to its Steering Committee for guidance of its activities. The committee is comprised of representatives of the Consortium's three member universities, the U.S. Department of Agriculture and the pork, meat and poultry industries. These committee members meet at least once a year and review research progress. As necessary, they recommend changes that may be required to accomplish the Consortium's congressional mandate.
The Consortium and its researchers benefit from the expertise and varied backgrounds the committee members bring to their task. They review the proposed projects for the next fiscal year to ensure that the Consortium is progressing toward meeting its purpose. These individuals take their roles seriously as contributing members of a team that has made its mark in food safety research in its few years of existence.
This year the Consortium Steering Committee has 12 members; five of them are new additions. Their first assignment was to prepare for the annual meeting in Kansas City and to become familiar with the projects they would be reviewing. The new members are:
* Frank Flora, food scientist and program manager for the USDA Cooperative State Research, Education and Extension Service in Washington.
* Brenda Halbrook, research coordinator for science and technology of the USDA Food Safety and Inspection Service in Washington.
* Jim Riemann, director of fresh meats for the Excel Country Fresh Meats Product Development Center in Wichita, Kan.
* Colin Scanes, associate director of the Iowa Agriculture and Home Economics Experiment Station and associate dean of the College of Agriculture at Iowa State University.
* Lee Ann Thomas, laboratory coordinator for the Food Safety Inspection Service's Animal Production Food Safety Program at the National Veterinary Services Laboratory in Ames, Iowa.
We thank these qualified individuals for agreeing to devote part of their time and energy to the advancement of food safety and the Consortium's efforts. We also thank the former committee members who recently stepped down from their positions. They are Dell Allen of the National Cattlemen's Association in Wichita, Clark Burbee of the Cooperative State Research, Education and Extension Service in Washington; Donald Derr of the Food Safety and Inspection Service in Washington, Tom Fretz of the Iowa Experiment Station and Stan Harris of the National Veterinary Services Laboratory.
The Steering Committee retains the services of several individuals who are joining me for another year of work on the panel. They are Ellis Brunton, group vice president for research and quality assurance at Tyson Foods in Springdale, Ark.; James Denton, director of the Center of Excellence for Poultry Science at the University of Arkansas and head of the Department of Poultry Science; Richard Forsythe, distinguished professor emeritus of poultry science at the University of Arkansas and the Consortium's former coordinator; George Ham, associate director of the Kansas State University Agricultural Experiment Station; Jack Riley, head of the Kansas State University Department of Animal Sciences and Industry, and Mike Telford, president of the Iowa Pork Producers Association.
The Consortium's Technical Executive Committee has undergone some changes. I am taking Dick Forsythe's place as chair and the Arkansas representative. Frank Flora is succeeding Clark Burbee as the CSREES representative. George Beran, professor of veterinary microbiology and preventive medicine at Iowa State, and Curtis Kastner, professor of animal sciences and industry at Kansas State, will continue on the committee.
Committee work is a calling and at times a burden, but its rewards are evident in the Food Safety Consortium. Thanks to everyone for their past, present and future service.
Numerous tests have been performed over the years to determine
the effects of irradiation on microorganisms. Food Safety Consortium
researchers at Kansas State University recently examined the effects
of low-dose irradiation on the quality of boneless pork chops,
beef steaks, precooked ground beef patties and raw ground beef
patties. They found that irradiation did not adversely affect
traits such as color, product life, flavor and aroma characteristics.
"I think the safety of irradiation is established," said Don Kropf, the principal investigator at KSU who headed the project. This set of irradiation studies was aimed at determining whether irradiation would cause quality changes that might leave consumers wary.
Irradiation preserves food by exposing products to high-energy ionizing radiation. The radiation energy changes the molecules so that, at sufficient doses, microorganisms are killed so they cannot cause spoilage or illness. A dose of food irradiation is the amount of radiation absorbed by the food.
The amount of radiation absorbed in dosages is measured in kilograys (kGy). The World Health Organization considers any food irradiated up to an average dose of 10 kGy to be wholesome and safe for consumption.
In the KSU project, the beef steaks were treated to irradiation dosages of 0, 2 or 3.5 kGy. Irradiated frozen steaks were thawed overnight; chilled steaks were stored 14 days, after which half of them were covered with PVC film overnight.
A panel of five professional flavor profilers assessed the steaks for attributes of texture and flavor. They found that irradiation did not influence the frozen steaks' toughness, juiciness, meat identity, browned-roasted traits, bloodiness, fat-like aspects, metallicness, liver-likeness, sweetness, sourness or bitterness, their internal or external cooked color values or aroma. In all the categories, the measured levels of those traits on the irradiated steaks were not significantly different from the levels recorded for the unirradiated steaks. The steaks' redness increased in the steaks irradiated in the 2-3.5 kGy range.
Irradiation also did not influence the chilled steaks' juiciness, fat-like aspects or their metallic, sweet or bitter flavor notes. It also did not affect their internal or external cooked color values.
Similar studies reviewed the results of irradiation when applied to frozen raw and precooked ground beef patties with raw fat levels of 10 percent and 22 percent. Patties were treated to doses of 0, 2 or 3.5 kGy. The results showed that the dosage level, the package type and fat percentage did not affect most of the patties' flavor and aroma attributes. Irradiation increased the external redness in the vacuum-packaged precooked ground beef.
The tests on the boneless pork chops measured consumer acceptance of irradiated chilled pork chops as well as flavor and aroma characteristics of chilled and frozen irradiated chops as assessed by the professional panel. There were few major differences between the control and irradiated chops despite varying irradiation sources, packaging types or storage temperatures. A panel of consumers --- 80 percent of them between ages 26 and 55, more than half having some college education --- observed no differences between the irradiated and control samples when evaluating the chops' overall acceptability, meatiness, freshness, tenderness and juiciness.
The pork chops study was the only one accompanied by a study of consumer acceptance. "Consumer studies are quite expensive," Kropf said, noting that funds were available for only one study.
Results of the research have already been presented at the 41st International Congress of Meat Science and Technology in San Antonio and at the American Meat Institute's mini-conference on meat irradiation at which Kropf was one of the four speakers. A press conference involving trade magazine representatives was also held in San Antonio. Kropf also expects to present the findings next year at the Institute of Food Technologists convention in New Orleans.
Noting the safety of irradiation is no longer in question, Kropf said there are still related aspects of the process that should be studied. "We think that the greatest need for research is to fine tune the system, particularly in regard to packaging," Kropf said.
Research on the steaks and ground beef was sponsored by the American Meat Institute Foundation and the Cattlemen's Beef Promotion and Research Board. The pork chops' study was sponsored by the National Live Stock and Meat Board and the National Pork Producers Council.
Richard H. Forsythe of Arkansas, a member of the Consortium
Steering Committee, was named a Fellow of the Poultry Science
Association in August during the organization's annual meeting
in Edmonton, Alberta. Forsythe recently stepped down as coordinator
of the Consortium and retired from the University of Arkansas
faculty, where he was a distinguished professor of poultry science.
The PSA grants the title of Fellow for professional distinction and contributions to the field of poultry science without concern for longevity. No more than five members may be elected as Fellows at any one annual meeting.
Forsythe has compiled a 47-year career in the academic world and industry, specializing in poultry products, food safety and nutrition. He produced 46 refereed journals from his research.
Forsythe earned his bachelor's and doctoral degrees at Iowa State University and served there as an instructor, an assistant professor and department head. He was an adjunct professor at Pennsylvania State University. After his employment in industry, Forsythe joined the University of Arkansas faculty.
His industrial experience included administrative duties associated with research related to product development and safety. Forsythe served as associate director for food research at Armour & Co.; director of central laboratories, vice president for research and vice president for technical affairs at Henningsen Foods, Inc.; and vice president for basic research at the Campbell Institute for Food Research of the Campbell Soup Co.
Forsythe has served on committees of several professional organizations, including the Poultry Science Association, the Institute of Food Technologists, the Institute of American Poultry Industries, the Poultry and Egg National Board, the World Poultry Science Association, the American Poultry Historical Society, the National Research Council, the Nutrition Foundation, the Southeastern Poultry and Egg Association and the Arkansas Poultry Federation.
His awards and honors include installation in the American Poultry Historical Society Hall of Fame, selection as Arkansas Poultry Federation Man of the Year and Poultry Industry Man of the Year, and receipt of the Contributions to Poultry Industry Above Gain for Self or Employer Award, the Missouri State Award of the National 4-H Alumni Recognition Program, the Institute of American Poultry Industry Research Award and the Monsanto Award. Forsythe has been named a Fellow of the Institute of Food Technologists.
Curtis Kastner and Randall K. Phebus and other
researchers from Kansas State presented a paper, "Standardized
Microbial Sampling and Testing Procedures for the beef Industry,"
at the 41st Annual International Congress of Meat Science and
Technology in August in San Antonio.
Daniel Y.C. Fung and Curtis Kastner of Kansas State presented a paper at the 41st Annual International Congress of Meat Science and Technology on "Reduction of Listeria Monocytogenes, Escherichia Coli 0157:H7 and Salmonella Typhimurium During Storage on Beef Sanitized With Fumaric, Acetic and Lactic Acids."
Melvin Hunt and Don Kropf of Kansas State presented a paper on "Expressible Juice and Internal Cooked Color of Ground Beef Patties From Vitamin E-Supplemented Steers" at the 41st annual International Congress of Meat Science and Technology.
James H. Denton of Arkansas presented paper on "Role of the Land Grant University in HAACP Education" at the Food Safety Workshop of the Poultry Science Association at the University of Alberta in Edmonton.
Paula J. Fedorka-Cray of the National Animal Disease Center at Iowa State has submitted four articles for publication in journals during 1995. "Alternate Routes of Invasion May Affect the Pathogenosis of Salmonella typhimurium in Swine" was published in Volume 63 of Infection Immunity. "Influence of Inoculation Route on the Carrier State of S. Choleraesuis in Swine" is in press at Veterinary Microbiology. Articles that have been accepted for publication are "Transmission of Salmonella choleraesuis to Naive Swine" in Applied Environmental Microbiology and "Effect of Dose on Persistence of S. Choleraesuis Infection in Swine" in the American Journal of Veterinary Research.
Daniel Y.C. Fung of Kansas State made several presentations in April in Brazil as part of the United States Information Agency's Scientific Speaker Program. At a symposium in Gramado, Fung lectured on biodeterioration and made a presentation and chaired a discussion on rapid methods. At the University of Sao Paulo, he lectured at the Institute of Food Technology and at the Department of Food and Nutrition on advances in rapid methods in microbiology. In Rio de Janeiro, he lectured at Federal Fluminense University on food technology and at the Rio State Foundation of Environmental Engineering on "Recovering of Biodegraded Waters, Water Purification and Treatment." In Recife, Fung lectured at the Federal University of Pernambuco and discussed "Water and Solid Residues in the Process of Environmental Degradation" and "Rapid Methods" at a lecture sponsored by the Brazilian Association of Sanitary Engineering. He also conducted a press interview on environmental clean-up suing rapid methods systems and met with reporters from O Globo and Ecologia e Desenvolvimento magazine. Articles about his visit were also published in O Estado de Sao Paulo and the Journal do Commercio.
In July and August, Fung was a visiting scholar to Budapest, Hungary, at the university of Horticulture and Food Science on an Organization for Economic Cooperation and Development Fellowship.
Fung was also recently designated a Fellow of the Institute of Food Technologists in recognition of his contributions to food science and technology.
In addition to his interviews in Brazil, Fung has been featured in several newspaper articles in recent months. He was interviewed in the Wichita Eagle in an article on food preparation practices; in Ouest France and in Food Chemistry News of Tokyo.
Fung was the author of "What's Needed in Rapid Detection of Foodborne Pathogens," which appeared in the June 1995 edition of Food Technology.
At the Kansas State campus in July, Fung was the director of the 15th anniversary workshop on Rapid Methods and Automation in Microbiology. About 150 people from 23 states and 15 countries participated in the eight-day workshop.
Richard H. Forsythe of Arkansas participated in the Institute of Food Technologists media training seminar in August in Chicago. The seminar, for food science communicators, covered working with news media.
Amy Waldroup of Arkansas received the Continental Grain Poultry Products Research Award in August at the Poultry Science Association meeting in Edmonton, Alberta. She received grants of $10,000 from Cargill, Inc., and $15,000 from Rio Linda Chemical Corp. The award is presented annually to the person who has accomplished outstanding research in the field of poultry products. Waldroup was cited for her work on food safety issues in poultry products, particularly with factors that influence salmonella contamination. She has focused on methodology of detection, intervention and eon points for salmonellae control and has suggested various feeding and management practices that aid in the reduction of salmonellae numbers on processed carcasses.
Waldroup also presented a paper in July entitled "Chemical Decontamination of Poultry Carcasses" at the annual meeting of the International Association of Milk, Food and Environmental Sanitarians in Pittsburgh.
Two articles that Waldroup co-authored were published in the May 1995 edition of The Journal of Food Protection --- "Performance Characteristics and Microbiological Aspects of Broilers Fed Diets Supplemented with Organic Acids" and "Antibacterial Activity of a Sodium Acid Pyrophosphate Product in Chiller Water Against Selected Bacteria on Broiler Carcasses."
Food Chemical News used material presented by Mary Scantling,Waldroup's research assistant, on the market quality of TSP-treated turkeys. The presentation was made at the Poultry Science Association meeting in Edmonton.
Chuck Banks, district director for Rep. Pat Roberts of Kansas, chairman of the House Agriculture Committee, met in September with Consortium researchers at Kansas State to review research projects.
Secretary of Agriculture Dan Glickman delivered the Landon Lecture in September at Kansas State. Consortium researcher Jim Marsden of Kansas State and representatives of the Kansas Livestock Association met with Glickman to discuss research and inspection issues.
The Food Safety Consortium Newsletter is starting a
new feature. Each edition will present a roundup of items about
developments in food safety around the nation. Sources include
announcements from public agencies, trade publications, general
interest newspapers and magazines and the Internet. And those
are just the items we see in this office. If you come across an
interesting article that ought to be brought to Newsletter
readers' attention, send it to us at 110 Agriculture Building,
University of Arkansas, Fayetteville, Ark. 72701, via fax to 501-575-7531
or through e-mail to firstname.lastname@example.org.
* * *
Sens. David Pryor of Arkansas and Richard Lugar of Indiana in August introduced the Food Quality Protection Act of 1995. The bill would reform the Delaney clause of the Federal Food, Drug and Cosmetic Act, a 1958 measure that set standards for pesticide levels in raw and processed foods. The Delaney clause allowed no tolerance of pesticide levels in foods, but "since that time, improvements in technology have shown us that traces of pesticides covered in the Delaney clause pose no public health risk," Pryor said. Pryor added that U.S. agriculture has been at a disadvantage in world markets because of the Delaney clause. The Pryor-Lugar bill would also create a single risk standard for pesticide levels in both raw and processed foods and also calls for the U.S. Department of Agriculture, the Environmental Protection Agency and the Department of Health and Human Services to coordinate their pesticide data collection procedures.
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USDA researchers have found that a bacterial blend called CF3 significantly reduces salmonella in broiler chickens. One hundred broiler chicks were treated with CF3 and another 100 were not. Two days later, all 200 chicks were each given 10,000 Salmonella typhimurium bacteria. Four weeks later, the broilers' intestines were checked and the CF3-treated birds had fewer than 10 Salmonella typhimurium bacteria per gram of cecal (intestinal pouch) content. The untreated birds each had about 3,000 Salmonella typhimurium bacteria.
"The results indicate treatment with this bacterial blend, which we call CF3, may be a useful part of an integrated program to reduce salmonella in broilers during growout and reduce salmonella in the chicken house," said Michael E. Hume, a research biologist with the USDA Agricultural Research Service.
The tests were conducted last spring at the ARS Food Animal Protection Research Laboratory in College Station, Texas. The researchers produced CF3 by selecting 29 different types of bacteria from hundreds present in the ceca of older chickens and using those microorganisms to produce a defined culture. Hume reported the results at the annual meeting of the Poultry Science Association in Edmonton, Alberta.
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Parade, the magazine inserted with hundreds of Sunday newspapers across the nation, published a full-page article in August by Peter Hellman entitled "Don't Let Your Food Make You Sick." The article explained that foodborne illnesses are often caused by the wide distribution of a product contaminated at a single plant. But it assured consumers that the key to keeping themselves safe from such problems is to practice routine precautions: keeping hands clean, keeping refrigerators at no higher than 40 degrees F, cooking foods at 180 degrees F, avoiding cross contamination in the kitchen (such as keeping utensils used to cut a raw chicken away from other foods until they have been washed), and cooking ground beef until no pink is left inside and juices run clear.