Pathogen Protection

By Donna Berry, Contributing Editor

The United States provides one of the safest food supplies in the world. Yet, lethal microorganismspathogens such as Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, Clostridium botulinum, Staphylococcus aureus and othersmanage to make their way into our food. Proper handling and effective cooking by the consumer inactivates pathogens; however, manufacturers must do their part to best eliminate their presence or prevent their growth.

The risk of contamination with foodborne pathogens cannot be prevented completely. Therefore, it is necessary to incorporate intrinsic hurdles to control or prevent the growth of pathogens beyond production control," says Larry Steenson, principal senior scientist, Danisco USA, New Century, KS. Hurdle technology is a combination of treatments and ingredients used to enhance shelf stability, safety and quality of foods. Antimicrobials, such as organic acids, bacteriocins, antimycotics and essential oils, can eliminate or inhibit the growth of microorganisms, including pathogens."

It is important to distinguish between technologies that ensure quality throughout shelf life, e.g., prevent spoilage, off flavors, discoloration, etc., and those that keep a food safe to eat. In fact, most reported cases of foodborne illness result from the consumption of perfectly palatable food. Invisible pathogens invade the body and wreak havoc. Because the end result can often be fatal, whenever pathogens are detected in food, the product is typically recalled.

Preventing a recall

Any type of product recall damages a brands reputation, and when it is related to food safety, oftentimes the damage is irreparable. After a life-threatening product recall occurs, such as what transpired earlier this year in the egg industry, competitive manufacturers will often invest in public-relations efforts to draw attention to their observable safety efforts. Securing consumer trust is of upmost importance in the food industry.

Such visible efforts, known as good manufacturing practices, or GMPs, are that first line of defense against dangerous microbes that lurk everywhere. However, most manufacturers will keep some food-safety efforts confidentialin particular, the addition of antimicrobials. Considered one of the multiple hurdles in food protection, it is important to remember that no antimicrobial will keep a food safe if GMPs are not followed from field to factory.

It starts on the farm

While the responsible parties for the contaminated eggs were being investigated, United Egg Producers (UEP), Atlanta, sponsored an animal-welfare conference for all types of media, from mommy bloggers to national news reporters. We wanted to get the message out that the U.S. egg industry has a long and demonstrated commitment to food-safety programs and uses tough food-safety measures to help protect against foodborne illness," says Gene Gregory, president and CEO, UEP. Chief among these methods are modern, sanitary housing systems; stringent rodent control and bio-security controls; vaccination of hens against Salmonella enteriditis; cleaning and sanitizing of hen houses and farms; and lots and lots of testing."

Unlike many foods sold to consumers directly from the farm, the eggs shell provides a natural barrier to pathogenic contamination. But what about once that shell is removed and the egg is processed into a liquid, frozen or dried ingredient? GMPs must continue.

The first step in producing an egg product is removal from the shell, followed by filtering and cooling to maintain quality while waiting for processing," says Elisa Maloberti, director of egg product marketing, American Egg Board, Park Ridge, IL. Further processing may include the addition of non-egg ingredients, mixing or blending, stabilizing, pasteurizing, cooling, and packaging for freezing or subsequent to drying. During all of these steps, GMPs are followed."

Patricia Curtis, professor, Department of Poultry Science, Auburn University, and director, National Egg Processing Center, Auburn, AL, adds: The USDA-approved pasteurization methods assure food manufacturers that theyre using high-quality, safe egg products. The companies involved in producing egg products conduct thousands of quality-assurance tests to be sure harmful bacteria are destroyed during the pasteurization process."

Processing technologies

Heat-induced pasteurization is the most-common process to destroy pathogens. However, a new USDA- and FDA-approved high-pressure pasteurization (HPP) technology has become available. This all-natural, environmentally friendly technology uses intense hydrostatic pressure to deactivate and destroy pathogens in pre-packaged, ready-to-eat (RTE) products, including meats, soups, wet salads, sauces, fruit smoothies, shellfish and seafood. By applying up to 87,000 lbs. of hydraulic pressure per square inch to RTE food products in their final packaging, our HPP process completely eradicates harmful bacteria, eliminating the need for chemicals and preservatives, without compromising the taste or texture of the treated products," says Guy Giordano, president, Safe Pac Pasteurization LLC, Philadelphia.

Best with moist foods without internal air pockets, HPP places pre-packaged products in flexible containers  into a high-pressure chamber, which is then flooded with cold water and pressurized for a short time period, usually three to five minutes. As pressure is applied uniformly around and throughout the product, reaching all parts of the product simultaneously, treated foods retain their original shape and texture.

Ingredient addition

Many formulators are increasingly choosing the clean-label" and all-natural" approach to product development and are avoiding traditional chemical preservatives, including benzoates, nitrites and sulfites. Because HPP isnt suited to every applicationdue to cost or the nature of the productformulators are challenged with identifying the most-effective natural antimicrobials for a specific foods. This range includes competitive microbial sources (bacteriophages, bacteria, algae, fungi, etc.), animal-derived products (certain milk proteins, chitosan, etc.) and plant components (essential oils, phytochemicals, organic acids, bioactive compounds, etc.).

Scientists have long recognized the inhibitory effect that lactic acid bacteria have on pathogensparticularly during the manufacture and subsequent storage of fermented foods. Not only do lactic acid bacteria convert carbohydrates into organic acids, which lowers the pH of the food matrix and prevents the growth of pathogens, they also produce and excrete a variety of inhibitory substances, including ethanol, hydrogen peroxide, diacetyl, free fatty acids, benzoate, antibiotics and bacteriocins. In addition, some beneficial microorganisms inhibit pathogen growth by consuming the resources that pathogens need to survive and proliferate.

Antimicrobials can effectively control pathogenic growth in refrigerated foods, with some based on lactic acid. We have developed an ingredient specifically for control of Listeria in select cured and uncured meat items. It is a natural product based on cultured corn sugar and vinegar," says Eva Dratwa, marketing services manager, Purac America, Lincolnshire, IL. In research studies, it was able to prevent two-log Listeria growth up to 120 days.

Another ingredient contains lauric arginate, a novel antimicrobial compound that can be used for bacteriocidal surface treatment of fresh and cooked meat against foodborne pathogens," continues Dratwa. It kills pathogens by acting on their cytoplasmic membrane and disrupting their metabolic processes."

Lauric arginate is a derivative of lauric acid, larginine and ethanol, all naturally occurring substances. It has a broad spectrum of antimicrobial efficacy (E. coli O157:H7, Listeria and Salmonella) over a wide pH range (3 to 7). Once consumed, it is hydrolyzed in the human body by chemical and metabolic pathways, which quickly break the molecule into its natural components.

In all applications, the maximum usage level is 0.2%. In fresh meats, it is considered a processing aid and does not need to be labeled," says Dratwa. In ready-to-eat meats, it is considered a processing aid and does not need to be labeled at levels up to 44 ppm.

We also offer a highly concentrated blend of potassium L-lactate and food-grade sodium diacetate," Dratwa adds. It can control pathogens in the new generation of low-sodium meat products with minimal or no taste impact on the end product."

Wash the bugs away

Like refrigerated meatsraw and cookedfresh produce is highly susceptible to pathogenic contamination. Chlorinated washes are the standard approach to cleaning produce for packaged and washed products, including the growing number of salad kits and fruit and vegetable snack packs.

Recently, a non-chlorinated produce sanitizer was released that maintains freshness and dramatically reduces microorganisms on certain leafy greens. It is a scientifically validated advancement for fresh-produce safety that delivers a substantial reduction in microorganisms on leafy greens, including superior microbial efficacy against such pathogens as E. coli O157:H7 Listeria and Salmonella, as compared to the industrys conventional chlorine sanitizers. Based on our extensive research, we view FreshRinse as the biggest invention since the start of pre-packaged salads," says Fernando Aguirre, chairman and CEO, Chiquita Brands, Orlando. FreshRinse sets a new standard in food safety for the produce industry. We plan to make this new technology available to the industry."

According to a third-party pathogen study performed by the National Center for Food Safety and Technology, Chicago, FreshRinse was shown to reduce nine times or more of E. coli O157:H7 and Salmonella on romaine lettuce and spinach versus chlorine produce washes. Specifically, FreshRinse reduced 78 times more Salmonella that were attached on romaine lettuce leaves. FreshRinse also resulted in more than 750 times greater reduction of suspended pathogens compared to chlorinated wash water.

The technology, which is considered a processing aid and thus does not need to be declared on ingredient statements, is the result of research by Kai-Lai Grace Ho, principal scientist, Fresh Express. It is a proprietary combination of GRAS ingredients and an FDA-approved ingredient that significantly enhances pathogen reduction and retains freshness. It is acceptable for use on both conventional and organic produce and is an environmentally friendly technology, as it will decompose to environmentally safe and friendly compounds, according to the company.

This is just a sampling of the many technologies available to food manufacturers to keep the U.S. food supply safe. The future will likely include many more clean-label, natural options.

Donna Berry, president of Chicago-based Dairy & Food Communications, Inc., a network of professionals in business-to-business technical and trade communications, has been writing about product development and marketing for 13 years. Prior to that, she worked for Kraft Foods in the natural-cheese division. She has a B.S. in food science from the University of Illinois in Urbana-Champaign. She can be reached at [email protected].