Deadly Ingredients

+ BY BERYL LIEFF BENDERLY

E. coli and other food-borne illnesses kill thousands annually. Now, researchers in the emerging field of food-safety engineering are trying to protect what we eat, from farm to table.

You won’t see celebrity chefs whipping up lunch in Ohio State University’s High Pressure Food Processing Lab. Yet Jamie Oliver and other healthy-eating evangelists would feel right at home in this state-of-the-art test kitchen, with its commercial-grade equipment, specialized fryers, and high-tech prep area. They’d also savor the facility’s mission: engineering recipes for ridding food of bacteria that sicken more than 1 in 6 Americans each year, 3,000 of them fatally.

Ohio State’s research lab, run by the Departments of Food Science and Technology and of Food, Agricultural, and Biological Engineering, is part of an emerging, multidisciplinary field aimed at curbing food contamination — and engineers have a prominent seat at the table. Call it the Food Safety Network, or as lab director V. M. Balasubramaniam, associate professor of food science and biological engineering, prefers, “food safety engineering.” Years before terrorism concerns and highly publicized outbreaks involving tainted spinach, eggs, and peanut butter spurred Congress to pass the Food Safety Modernization Act last December, engineering educators across the country were working with microbiologists, chemists, food scientists, and other faculty on innovative technologies to protect and follow foods. Their method: apply engineering principles to address microbiological and chemical food-safety challenges and develop unconventional solutions to imminent problems. In essence, says Carmen Moraru, associate professor of food science and technology at Cornell University, this new specialty “denotes a quantitative approach to food safety.”

COOKING UP PROTECTION

Humans have sought trustworthy methods of preparing and preserving food since hunter-gatherer days. The most common, time-honored means of keeping food safe is what food engineers call “thermal processing”—a.k.a. cooking. Other methods of disinfecting and preserving food, such as drying, smoking, pickling, and flavoring with microbe-killing spices or salt, also have ancient pedigrees. The 19th and 20th centuries brought two more-advanced thermal methods: canning and freezing. The former, invented to feed an army during the first years of the Napoleonic wars, produces some of “the safest food you can have,” says biology Prof. Robert Brackett, director of the Institute for Food Safety and Health at the Illinois Institute of Technology (IIT).

These traditional techniques all alter the appearance, taste, and texture of food, however. Most also reduce such nutrients as vitamins. Over the past decade, the unappetizing effects of heat, cold, and canning have become less acceptable in the marketplace. Consumers began demanding “minimally processed foods [that] can retain more nutrients for health and wellness,” along with sensory qualities much closer to the fresh state, notes Balasubramaniam. So industry began investigating different approaches.

The new federal food-safety act, which took effect in January, has added urgency to industry’s quest for innovation. The law requires food processors to use “science-based preventive controls” to hinder contamination and to track both domestic and imported foods from farm to table so that tainted products can quickly be pinpointed and recalled.

One well-developed nontraditional, nonthermal method familiar to many consumers is irradiation, also known as cold pasteurization.The technique, which won FDA approval in 1990, uses ionizing radiation — specifically gamma or beta rays produced by X-ray or electron beam — at levels high enough to fatally rupture the chemical bonds in the DNA of salmonella, Listeria, or other microbes but low enough to avoid rendering the food radioactive or alter its sensory and nutritional qualities. Although experts consider irradiation perfectly safe, it has suffered from bad publicity. FDA regulations require labeling when used. Ozone, used to kill bacteria, viruses, and other microbes on food-processing surfaces, is also recognized as safe by the FDA. Because it inactivates microorganisms as effectively as chlorine without any residual chemicals, it now is being applied directly, in both gaseous and aqueous forms, to a variety of fruits, vegetables, eggs, fish, poultry, and meat.

An innovation for destroying bacteria, pulsed electric-field processing, has proved effective against molds, yeasts, and bacteria and is suitable for liquids. Food is placed between two electrodes, then subjected to high-voltage pulses that cause microbes’ cell membranes to rupture.

Perhaps the most advanced new method is high-pressure processing (HPP). This minimalist technique kills many bacteria and some viruses by subjecting food to pressures similar to those required to make industrial diamonds, explains Balasubramaniam. Unlike thermal treatment, pressure acts equally at all points of a product and thus eliminates the denaturation, browning, and film formation associated with cooking and canning. And because HPP does not cause changes in texture or taste, it is appropriate for foods easily ruined by heat, such as guacamole, raw oysters, salsa, smoothies, and a host of ready-to-eat meals.

The lab where Ohio State’s Balasubramaniam and fellow food-safety engineers are working with industry to perfect HPP resembles a mix of high-tech NASA design shop, commercial food plant, and Julia Child’s kitchen. Hoisting food samples as large as 5 liters into a pressure vessel, researchers study the effect of applying anywhere from zero to more than 100,000 pounds per square inch of pressure on both microbes and foods. A specially programmed computer allows them to control pressure, temperature, and other parameters, while specialized devices provide such information as the reaction of bacterial spores and microbes to various pressure and heat conditions. A nearby kitchen also stocks familiar tools for preparing foods to study, with other university facilities providing professional-grade devices that can peel, chop, freeze, fry, extrude, homogenize, and package foods.

WRAPPING UP SAFETY

In addition to microbe-killing innovations, food-safety engineers are investigating new methods for detecting contamination and designing packaging that does more than just keep food fresh. A number of techniques found in molecular biology and electrical engineering have been adapted to produce assays and biosensors that can rapidly identify pathogens. After seven Chicago-area residents died from poison-laced Tylenol in 1982, demand soared for tamper-resistant packaging. Similarly, notes IIT’s Brackett, the new federal food-safety act will compel food producers to evaluate “the risk of the product being tampered with. They’ll have to come up with new processes to guard against that.”

“Active” or “smart” packaging offers detailed tracking and flagging of foods. Various types of materials, for example, can either absorb potentially detrimental materials, such as excess moisture, or release helpful ones like antioxidants or antimicrobials. Packages containing sensors can warn companies and consumers of contamination or recalls. The three-decade-old bar code may soon be superseded by radio frequency identification (RFID) tagging, which is coming into increasing use in the food industry. RFID tags (also called transponders) contain a microchip and tiny antenna, allowing them to “talk” to electronic readers. When attached to packages, they can record and convey information about each food item contained and the route each shipment has followed. The devices work both with processed foods in cans and boxes, and with fresh fruits and vegetables as long as the tags can be securely attached to bags, ties, or boxes. Unlike bar-code scanners, RFID readers do not require “line of sight” contact to receive information.

In Carmen Moraru’s lab at Cornell, food-safety engineers are exploring advanced technologies that use short pulses of intense light to kill microbes. Researchers say this method shows potential as a swift, relatively inexpensive way to clean food-preparation surfaces and equipment. Moraru’s team also is investigating membrane-separation techniques aimed at removing bacteria and spores from raw milk. The result, they hope, will be dairy products with fresher taste and better nutrition because it will take less heat to make them safe.

AN ADVANCING FIELD

As the need to safeguard food expands, so does the range of expertise demanded of engineering educators in this exciting new specialty. A food-safety engineer must be “quite knowledgeable in engineering fundamentals and at the same time needs to answer or address how [foods] are safe microbiologically,” notes Ohio State’s Balasubramaniam. Like him, many pioneers have food, chemical, or mechanical engineering backgrounds, “but through experience now we are forming this subset called food-safety engineering.” IIT’s Brackett notes that “electrical engineers developing electronic processes, logic processes, have become much more engaged.”

Preparing students for careers in food-safety engineering may require academic adjustments. Food science and food engineering typically have resided in schools of agriculture, not engineering. Moreover, most offer subfields in food engineering, food chemistry, or food technology rather than a full menu of courses. Some universities, such as IIT, offer graduate degrees or programs with “food safety engineering” in the title. However, at this point, it’s “more of an area of research within the broader area of food science, very interdisciplinary by nature,” says Cornell’s Moraru.

The small field may expand as more engineering students recognize its potential to protect life. Ohio State’s Balasubramaniam believes one way to grow the field might be to identify interested science and engineering graduates and build up any missing expertise. “Bring in your highly qualified engineering graduate and have that person take courses in food microbiology,” he suggests. “Or you can also bring in someone who is strong in microbiology and then have them take more engineering classes and then conduct research.”

Will food-safety engineering join bioengineering as an interdisciplinary field in its own right? “I know to never say never,” says Cornell’s Moraru, who sees it remaining a specialized subfield of food engineering, with links to biological and agricultural engineering. On the other hand, she notes, increasing public and industry interest in food safety ultimately “may be the common denominator” that creates a signature dish from today’s disparate academic ingredients. Bon appétit!

Beryl Lieff Benderly is a freelance writer based in Washington, D.C.