Questions, comments or suggestions may be directed to: Ellen Varley, ev1@umail.umd.edu phone: (301) 405-4581

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From the Director's Desk

Faculty of the Cooperative Extension Service are actively involved in numerous research and outreach programs designed to ensure the safety of the American food supply--from the farm to the table. Much of their work focuses on microbial contamination.

For example, interdisciplinary teams of scientists are developing ways to identify and reduce pathogens such as Salmonella on commercially produced and processed foods. Home economics agents throughout the state are helping consumers and food industry workers reduce their risk of foodborne illness by teaching seminars, testing home pressure canners, and sharing food safety information in a variety of ways. They receive support from a faculty Food Safety Rapid Response Team that updates agents on "hot" food safety issues.

This issue of Focus highlights the efforts of Extension faculty in the area of food safety. I think after reading about their work, you'll agree that the safety of our food supply is in good hands.

Thomas A. Fretz
Dean, College of Agriculture and Natural Resources
Director, Cooperative Extension Service

Scientists Wage War Against Salmonella

First Line of Defense

Evidence of a link between Salmonella contamination on the farm and on poultry carcasses has been accumulating for many years, according to Dr. Edward Mallinson, an Extension veterinarian with the Virginia-Maryland Regional College of Veterinary Medicine at the University of Maryland, College Park. Building on this evidence, he and his colleagues at the University of Maryland and the University of Delaware recently conducted a demonstration project funded by the Cooperative State Research, Education and Extension Service of the U.S. Department of Agriculture.

The goal of the project was to demonstrate the potential impact of lowered relative humidity or water activity (Aw) at the surface of poultry bedding--called litter--in possibly reducing the Salmonella contamination of processed broiler carcasses. "Aw represents the relative amount of free, unbound molecules of water in or around a substance or surface," explains Dr. Sam Joseph, a University of Maryland microbiologist involved in the demonstration project. "These molecules of water provide bacteria and other microbes with circumstances favorable to their multiplication."

"The value of reducing water activity in processed foods has been recognized for centuries as an essential practice in reducing bacterial spoilage," adds Mallinson. "Water activity levels also may be a key food safety consideration at the on-farm phase of the food production process."

Studies by such researchers as Dr. Lewis Carr, an Extension agricultural engineer, have revealed that those Aw levels associated with high or low risks of bacterial food spoilage are very similar to those associated with the risks of Salmonella- positive versus Salmonella-negative litter surfaces.

The demonstration project team conducted their study on three broiler farms over a period of a year and a half. Broiler chicks were raised in unaltered chicken houses and in houses in which steps had been taken to reduce the Aw of the litter surface. The litter was evaluated for detectable Salmonella and Aw values at the beginning, middle and end of the study. Birds from each house were then processed at the Princess Anne Poultry Research Facility of the College of Agriculture's Lower Eastern Shore Research and Education Center (LESREC). Researchers there determined the amount of Salmonella on each carcass.

The results of the project strongly suggest that the risk of Salmonella contamination on processed broiler carcasses is reduced when the birds originate from farms with low levels of Salmonella on the litter surface, says Dr. Charles Wabeck, an Extension poultry specialist at the Princess Anne facility. The results also revealed that low litter-surface Aw levels, which were confirmed to be associated with low levels of Salmonella in the litter, may also be associated with reduced risks of contamination on carcasses.

A related finding with important implications for poultry processors, according to Wabeck, is that the incidence of Salmonella on the carcasses can be cut substantially if Salmonella-negative birds are processed before Salmonella- positive birds.

Armed with data from the demonstration project, researchers are now trying to identify the environmental, processing, and management factors that most significantly and consistently reduce litter-surface Aw. "We're cooperating closely with poultry producers," says Mallinson. "Growers and company managers are very interested in any practical innovations that will help them protect the quality of their product, human health, and the environment."

A Promising Tool

"We were looking for a safe, practical way to eliminate pathogens, such as Salmonella, and to reduce the microbes that cause spoilage," says Heath. "And we found it." Their results revealed that irradiation could eliminate Salmonella, reduce the number of some other common pathogens, and extend the refrigerated shelf life of poultry up to 30 days.

Such benefits make irradiation a valuable food preservation tool both in the United States and abroad. "The World Health Organization is very enthusiastic about irradiation," says Heath, "because it would improve our ability to ship perishables to countries where refrigeration is minimal, preserving food long enough to get it to those who need it."

Building on their previous success, he and his colleagues are continuing their research. Through a joint project with Iowa State and Louisiana State universities, they are investigating how irradiation affects the quality and refrigerated shelf life of shipped and stored poultry when used alone or with other preservation treatments.

And, in a separate study, they are taking a similar look at how irradiation affects the same characteristics of fish. "We want to make sure that the taste, texture, and other sensory qualities of the product are maintained," Heath explains. "Because unless it tastes right, it doesn't matter how safe it is. People won't eat it."

Detecting Foodborne Pathogens

They are developing more rapid, efficient, and inexpensive methods of detecting foodborne pathogens, such as Salmonella. These tests meet the guidelines in pending meat and poultry inspection regulations, are less time consuming and complex than current tests, and can be conducted on farm samples, as well as on processed products.

"The greatest benefit of these methods," says Dr. Joseph, "is that they will provide a direct count of pathogen risk levels overnight with a minimum of test materials. This makes it possible to analyze a much larger number of samples on a given day." And that's good news for everyone.

Separating Fact From Fiction

"The Rapid Response Team was created to communicate important information on food safety issues, especially those featured in newspaper articles or on prime time television shows that create alarm among consumers," says Dr. Mark Kantor, Extension food and nutrition specialist and coordinator of the team. "We let Extension agents know that stories are being published or broadcast and provide them with information they can share. That way, when Extension offices are flooded with calls, the agents can respond effectively."

The idea for a Rapid Response Team originated several years ago but the commitment needed was lacking, according to Kantor. Then in early 1994 the U.S. Department of Agriculture (USDA) hosted a national meeting on food safety, and Extension's annual conference focused on an interdisciplinary team approach to addressing important issues. These conferences, combined with the growing media emphasis on food safety, served as the catalyst for establishing the Rapid Response Team.

The team, composed of faculty from various disciplines, communicates with Extension agents via electronic mail. For example, if team members see a broadcast on Thursday evening, they can send an e-mail message to the agents by Friday morning. The message summarizes the issue and provides advice on what to tell consumers. It may also include comments from professionals or a news release from USDA or other regulatory agencies.

Since the program was initiated, rapid response alerts have been transmitted on the accidental contamination of General Mills cereals with low levels of pesticides not approved for that use, the USDA's pathogen reduction legislative proposal, and outbreaks of foodborne illness caused by Salmonella in ice cream and a harmful strain of E. coli in salami.

Kantor says feedback from Extension faculty on the alerts has been positive. According to one agent, "the rapid response alerts allow us to feel as if we are on top of food safety issues and to have answers when customers call."

The next goal of the Rapid Response Team, according to Kantor, is to compile a list of resources on different food safety topics. The list would be posted on the gopher server at the University of Maryland, College Park, so that anyone with a computer could access it. "It's the logical next step in providing Extension agents and consumers with accurate, unbiased information about food safety," he says.

Home Economists Educate Consumers

On the Air

"The goal of the show is to present information to consumers in an interesting manner so they can use it right away," says Greene. The show features a live dialogue with a guest "expert" on a selected topic. Consumers can call in with questions.

Food safety topics are covered regularly. Just before Thanksgiving, for example, Greene discussed issues relating to turkeys and holiday feasting with Diane Vann, home economist with USDA's Meat and Poultry Hotline. "We had a number of calls during that program," Greene recalls. "One concern was how long the meat could be kept if all of the turkey was not used during the first meal. We suggested taking the meat off the bone and freezing it in plastic bags. That way, it could be kept for weeks or even months."

On another show, Dr. Mark Kantor, Extension food and nutrition specialist, discussed concerns about the bacterium E.coli and ways to avoid cross contamination when handling raw food.

On Display

"We did an exhibit on food safety during the holiday season because the second highest number of cases of food poisoning occur at that time of year," says Gwendolyn Jackson, a certified home economist and interim director of the Baltimore City Extension office. She thinks the exhibit is an effective medium for teaching the facts about food safety. "Once someone looks at it, they can grasp both the specific facts and the general concepts of food safety," she explains.

Extension agents in Frederick County began using displays to educate people about food safety and preservation after receiving requests to participate in local health fairs, says home economist Sandy Corridon. Faculty assistant Kaye Derr constructed the displays.

A "Food Safety: It's Up to You" exhibit contains information on such topics as danger zone temperatures, cross contamination, and general safety rules like "when in doubt, throw it out." It has been used at a county employees health fair, on cable television, and during training programs for home economics teachers and day-care providers.

Demonstrations are often conducted to attract attention to the exhibit. One such experiment involves three slices of bread that were handled and placed in baggies for several days. One slice was touched by unwashed hands, another by hands that were rinsed, and the third by hands that were thoroughly washed. The mold growth on each slice is compared at the exhibit site.

"That experiment is always well received," says Corridon. "It makes such an impact because there is a noticeable difference in the mold growth, which makes people realize the importance of washing hands thoroughly before handling food."

On-Site Food Safety Tours

"It's a good environment for teaching nutrition, as well as food purchasing, safety, and storage skills, because it's one that consumers frequent all the time," Pergerson says. She starts the tour in a classroom. The group then goes through the market aisle by aisle early in the morning, when fewer people are in the store.

Pergerson pulls items off the shelves and encourages everyone to look at labels for storage time and the "sell by" date. She asks people to observe how bulk food is packaged in bins and that employees use gloves and tongs to handle such items.

"When most people grocery shop, they are rushed and don't know exactly what to look for," says Pergerson. "The tours gives consumers a comfort zone in which someone is there to answer their questions, and they can take their time looking at the little things that make a big difference in food safety."

Unexpected Lesson

"When class participants ask how they can save money, I say: 'look in your refrigerator,'" says Hamilton. "Properly stored food can increase not only your health but also your wealth. People throw money away all the time in the form of spoiled food from their refrigerators. That slime in the bottom of your crisper isn't rotting dollar bills but it might as well be."

Is It Safe To Eat?

Some Common--and Uncommon--Food Safety Questions

Question:My freezer has stopped working. What should I do with the frozen food? Will it be safe to eat?
Answer: Keep the freezer door closed. The food inside will stay frozen longer if you avoid letting the cold air out and the room temperature air in. Once the freezer is working again, you can refreeze items on which ice crystals are still visible. Meat that has begun to thaw should be cooked; you can then refreeze the casserole or stew made with the cooked meat. Meat, poultry, and seafood that have completely thawed and are warm to the touch should be discarded.

Question: I accidently left some perishable food unrefrigerated. Is it still safe to eat?
Answer: If the food was left at room temperature for less than two hours (including the time needed to prepare the food), it's safe to eat. If it was unrefrigerated for longer than that, throw it away.

Question: I found some frozen food at the back of my freezer. It may have been there a couple of years--I don't know. Is it still safe to eat?
Answer: Yes, if it has been frozen solid the entire time. The flavor and texture of the food may have deteriorated, but it is safe to eat.

Question: I want to can some fruits and vegetables at home. How long and at what temperature must I heat the filled containers?
Answer: The Cooperative Extension Service has fact sheets on how to can a variety of specific fruits and vegetables. Follow the directions described in these publications.

Question: How long can canned foods be kept?
Answer: The amount of time you can safely store canned foods varies. Generally, high-acid canned goods, such as citrus juices and fruits, can be stored in the cabinet for 12 to 18 months. Low-acid items, such as stews, corn, beans, and spaghetti products, will keep for 2 to 5 years. All canned items should be stored in a cool, dry area. Check cans for swelling, seepage, or dents before use; if they show any of these signs, discard them. Don't taste questionable items; if in doubt, throw them out.

Question: Is canned food that has been frozen safe to eat?
Answer: Yes, as long as the cans aren't bulging, swelling, or seeping. The quality of the food may not be perfect, but it is safe.

Question: One of the eggs in the carton I bought is blue. Is it safe to eat?
Answer: Yes. The egg was laid by a breed of chicken called the Aracauna. Unlike most chickens, whose glands release pigments that produce white or brown eggs, the Aracauna secretes pigments that cause blue- or pink-hued shells. Except for this noticeable difference, Aracauna eggs are the same as those of any other chickens.

Pressure Canner Testing:
Putting a Lid on Foodborne Illness

To help prevent this scenario from occurring, the Cooperative Extensive Service offers Maryland residents information on safe canning procedures and free pressure testing of home canner gauges. Such testing is offered at all local Extension offices.

Correct Calibration Essential

Such testing is essential, agrees Joanne Hamilton, an Extension home economist in Anne Arundel County. "Correctly calibrated pressure canners are able to reach 240 degrees--the temperature needed to destroy the botulism-causing spore," she explains.

The absence of bad odor and taste often makes Clostridium botulinum and other pathogens silent killers. And tasting contaminated food could prove to be life threatening. Howard County Extension home economist Madeleine Greene recommends checking the seal on home-canned items to see if food has been correctly preserved. "Unscrew the metal screw band as soon as it has cooled," she says. "If the lid comes off easily, it has not sealed and should be reprocessed."

A Valuable Service

Such thorough examination is critical, according to Extension home economist Irmgard Koscielniak. Koscielniak tested 20 to 30 canners last year in Garrett County, where the number of young people starting to can home-grown produce is increasing steadily. Many of these "newcomers to canning" are using secondhand canners that are very sturdy but may be inaccurate. "I tell people, 'if you buy a canner secondhand, have it tested!'" urges Koscielniak. "You should also have it tested if you drop the lid. It may not look damaged, but the slightest change to the lid can affect the gauge reading."

At the other end of the state, in Caroline County, home economists test an average of six canners per year. "We used to test about 25 canners a year, but fewer people are canning today than they used to," says Donna Kimball, Extension home economist. "Freezing fruits and vegetables has become more popular."

Still, as Ingrid Holmes, a Wicomico County Extension agent who has been testing canners for 10 years, says: "If only one person cans their food safely as a result of having their canner tested, then the service we provide is of great value."

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Food Safety for Food Service Workers

One such program is an annual Food Safety Symposium designed primarily for food industry workers. Introduced four years ago, this event is sponsored by home economists from the city of Baltimore and the counties of Anne Arundel and Howard. The 1995 symposium will take place on April 20 in College Park.

"Our goal is to help dietitians, teachers, laboratory technicians, and food managers from schools, government agencies, hospitals, and other organizations--as well as members of the general public--improve their knowledge of food safety issues," says Constance Pergerson, a registered dietitian and area Extension agent. These issues include pesticides, biotechnology, water quality, irradiation, and microbial pathogens.

Accelerating the Process

"This is a very timely topic," he says. "A few genetically engineered food products are already available in some supermarkets and more are being developed all the time."

According to Kantor, extensive research supports the safety of genetically engineered food. "Basically, all we're doing is accelerating the plant breeding process, but in a very precise way," he says.

In most cases, genetically engineered foods will not be regulated differently than other new foods or require special labels. There will be exceptions, however. For example, special labels will have to be displayed on genetically engineered foods that contain a substance from another food to which people are allergic. Companies developing genetically engineered foods will be required to demonstrate that the nutrition of the product is not adversely affected and that natural toxins known to be present in the conventional food are not significantly elevated in the new food.

Safer Than Consumers Think

"People have this idea that there are tons of illegal pesticides on produce, and that just isn't the case," he says, citing the results of FDA's annual "market basket" survey.

Agency inspectors evaluate a variety of fresh fruits and vegetables from stores around the country and imported shipments from around the world for some 80 pesticides. In 1993 (the most recent year for which figures are available), only 2 percent of the domestic samples contained residues of pesticides not approved for use on a particular product or levels of approved pesticides in excess of tolerance limits set by EPA. Four percent of imported samples were similarly deficient.

"These results should increase public confidence in the safety of our food supply," Schlimme says.

From Farm to Kitchen

Dr. Suzanne Curtis, nutrition and food science lecturer, will explain how many restaurants and food companies are using HACCP (Hazard Analysis Critical Control Point) to reduce the risks associated with foodborne illness.

"HACCP involves analyzing a food product and the processes used in preparing or packaging it," says Curtis. "You prepare a flow chart and determine where in the process something could go wrong. Once you've identified these critical control points, you set up standards to avoid any problems." This approach is as applicable to home kitchens as it is to factories or school cafeterias.

The Forgotten Nutrient

He will discuss the human health effects of drinking contaminated water and explain the Environmental Protection Agency's drinking water standards, which are used to ensure good water quality and protect public health. These standards protect consumers from microbial contaminants, radioactive elements, and toxic chemicals by limiting the highest allowable concentration of a contaminant.

"Although drinking water standards can't guarantee that the water from your faucet is absolutely safe and pure," says Weismiller, "they provide monitoring guidelines that reflect sound scientific judgment and are based on all the knowledge available at the time the standards are set."