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PRODUCT SPOLIGHTS:
Interventions to Control Listeria monocytogenes in Seafood Products
By Tsui-Yin (Linda) Wong
The U.S. Centers for Disease Control and Prevention (CDC) estimates that approximately 2,500 individuals are seriously infected each year with Listeria monocytogenes, a foodborne pathogen that causes severe and potentially fatal disease. The fatality rate of this microorganism is approximately 25% among affected individuals. Listeriosis is rarely associated with the consumption of seafood products; however, the CDC warns that susceptible individuals consuming certain non-cooked seafood products may be at risk of becoming infected by L. monocytogenes. The European Union (EU) and the FDA have allowed up to 102 CFU/g of this microorganism in ready-to-eat (RTE) seafood products.
At the end of a processing day, this microorganism can cause a high level of contamination in the plant. To reduce heavy loads of this microorganism, more research needs to focus on a single process or combinations of processes. The choice of process needs to be easy-to-use, cost effective and safe for both workers and the environment. These processes are listed below:
Physical
Carbon Dioxide (CO2). Previous research found that seafood products packed with CO2 at a concentration of 100% and stored at cold temperatures (-1.5 °C~3 °C) may be protective against the growth of L. monocytogenes. Carbon dioxide and combinations of other antimicrobial agents (e.g., nisin, sodium chloride, etc.) were also studied. Research data showed CO2 may enhance the anti-listerial activity of these antimicrobial compounds. Packing with CO2 has another advantage in that it can be applied to any type of packaging material.
High Pressure Processing (HPP). This technology has been used extensively against Gram (+) and Gram (-) microorganisms in sauce products. Studies have been shown that vegetative cells are less resistant to this process than spore cells. HPP was recently used as a post-process treatment against L. monocytogenes in RTE seafood products. Previous studies reported the highest pressure treatment to destroy L. monocytogenes was 200 MPa in cold-smoked salmon. However, a lightness of this product was observed at such pressures. More studies are needed to evaluate the organoleptic properties (color, flavor, texture, etc.) of processed seafood products at this level of pressure or greater.
Pulsed Electric Field (PEF). This process has been used commonly in eliminating Gram (+) and Gram (-) microorganisms from fluid and semi-fluid products, such as milk, juice and liquid egg yolks. A field strength of 20–80 kV/cm and treatment time of microseconds (µs) were applied to these products. However, this process is limited for solid foods (e.g., seafood). Since PEF has a greater impact on microbial numbers in fluid and semi-fluid products, it can be applied to reduce the number of microorganisms in wastewater.
Chemical
Acidified Sodium Chlorite (ASC). ASC at levels of 40–50 mg/L in water or ice has been approved by the U.S. Food and Drug Administration (FDA) for use in rinsing, thawing, transportation and storage of seafood products.[1] This antimicrobial has more inhibitory activity at low pH (2.2–2.9) and may require neutralization by other antimicrobials (e.g., sodium thiosulfate). The inhibitory process of ASC toward microorganismal survival involves interference of cellular protein synthesis. A study found that experimentally contaminated L. monocytogenes on salmon fillets was more sensitive to this antimicrobial than salmon skins.
Cetylpyridinium Chloride (CPC). CPC is a cationic surfactant belonging to the group of quaternary ammonium compounds (QACs). Since it is a surfactant, the inhibitory activity of this antimicrobial relies on its surface activities for destroying the membranes of microorganisms. Concentrations of 0.05%–1.0% are used in RTE products against the growth of L. monocytogenes. Residue problems remain if this antimicrobial is directly applied on the surfaces of RTE products. An extra washing step may help to bring residue levels down. This antimicrobial is applied as a spray to decontaminate carcasses in the broiler industry. An experimental study also showed the decontamination of raw and RTE shrimp by immersing food product in a CPC solution.
Organic acids. The listericidal activity of organic acids has been reported in marinated seafood during chill storage. Such activity relies on an unassociated form of the acid (HA). One study previously reported that acetic acid (0.75–3.0%) could cause a significant reduction in L. monocytogenes populations in green shell mussels.
Biochemical
Epsilon(ε) polylysine. ε-polylysine, an antimicrobial peptide, consists of a homopolymer of 25 to 35 L-lysine residues. The inhibitory mechanism of this antimicrobial involves surface charges interactions. In Japan, concentrations of 1,000–5,000 mg/L ε-polylysine was used for spraying or dipping sliced fish and fish sushi.[2] In 2004, the FDA approved the use of this antimicrobial in cooked or sushi rice at levels up to 50 mg/kg.[3] This antimicrobial peptide has been examined experimentally against L. monocytogenes populations in food extracts and liquid media. Scientific studies showed ε-polylysine at levels of 0.01–0.02% reduced L. monocytogenes populations effectively at 4 °C and 24 °C in vivo. These experiments indicated that this antimicrobial can be used for decontamination of L. monocytogenes in RTE fish products, boiled rice, noodles soup stocks, noodles and cooked vegetables.
Lactic Acid Bacteria (LAB). Inhibitory activities of LAB against L. monocytogenes at 105 CFU/g or greater have been reported in several studies. Results showed the potential use of this antimicrobial to inhibit L. monocytogenes in RTE seafood products. LAB suppressed other microorganisms by producing a wide range of antimicrobial metabolites, such as organic acids, hydrogen dioxide, and diacetyl and bacteriocins.
Treatment Combinations
Treatment combinations are also called hurdle treatments/processes. Each treatment inhibits microorganisms in its own way. For example, packaging materials can prevent foods from coming into contact with excess moisture or oxygen. When more treatments were applied, a more unfavorable environment is created, limiting the growth of microorganisms. Treatment combinations, such as nisin + sodium chlorine + vacuum or 100% CO2, or potassium lactate (PL) + sodium diacetate (SDA) + frozen (-20 °C) + thawed (4 °C), have been reported to inhibit the growth of L. monocytogenes on cold-smoked salmon. The mechanism of treatment combinations involves either one treatment enhancing the antimicrobial activity of the other treatment or one treatment increasing the sensitivity of L. monocytogenes to the other treatment.
Conclusion
Which one of these processes is the best fit for current or future seafood processes? The obvious answer is a combination of processes. Implementing multiple treatments is not difficult. In this instance, products are decontaminated by antimicrobials and packed with CO2. Multiple treatments may help processors produce safe products without comprising organoleptic characteristics. Which specific multiple treatment is best? There are four important criteria to consider: convenience, economy, safety and environmentally friendly. ♦
Tsui-Yin (Linda) Wong received her Ph.D. in Food Science and Technology from Texas A&M University and is currently a seafood safety consultant. She has worked in the area of food safety for 6 years, performing research on Listeria spp. in seafood. She can be contacted at lindawong6618@gmail.com.
References
1. Anonymous. 1999. 21CFR 173.325. Acidified sodium chlorite solutions. Code of Federal Regulations. Office of the Federal Register, U.S. Government Printing Office, Washington, D.C.
2. Hiraki J., T. Ichikawa, S. Ninomiya, H. Seki, K. Uohama, H. Seki, S. Kimura, Y. Yanagimoto and J. W. Barnett. 2003. Use of ADME studies to confirm the safety of ε-polylysine as a preservative in food. Reg. Toxicol. Pharmacol.
37:328-340.
3. http://www.accessdata.fda.gov/scripts/fcn/gras_notices/grn000135.pdf.
Working with Companies to Safeguard Food
By Nicole E. Miller
This past summer, Kathy Glass and her team made batches of pepperoni in her laboratory-cum-kitchen in the Microbial Sciences Building at the University of Wisconsin-Madison. But it would have been a very bad idea to put her handiwork on top of a pizza. Stuffed into each casing, along with pork and spices, were Escherichia coli bacteria, the kind that make people sick—and sometimes die.
Glass manages the UW-Madison Food Research Institute's Applied Food Safety Laboratory, where it’s common practice to add dangerous bacteria and fungi to all sorts of processed foods. When her team is not lacing pepperoni with E. coli, they make contaminated cheeses and other deli meats, all in the name of protecting human health. The tainted foods help Glass study how foodborne pathogens spread through the nation’s food system and search for ways to stop them.
One needs only to look at the headlines to understand the importance of that quest. Foodborne illnesses sicken approximately 76 million people in the United States each year, and kill about 5,000. The E. coli bacterium, while not one of the top offenders, is particularly deadly; just a few stray cells can kill. One of the worst incidents occurred in 1993, when a particularly dangerous strain of E. coli, known to scientists as O157:H7, contaminated hamburgers sold by the Jack in the Box chain, killing four people and sickening more than 700.
Glass and other scientists have been able to come up with ways to prevent contamination from the O157 strain in meat processing. But in recent years, other, less-familiar types of E. coli have emerged. Public-health officials believe that these strains may account for 20 to 30 percent of all E. coli contamination cases nationwide.
Naturally, the meat industry is concerned, and that's why Glass is preparing bad meats. The Grocery Manufacturers Association (GMA), which represents hundreds of food, beverage and consumer products companies across the nation, has funded Glass’s project to study the emerging strains to assess how they fare under different food-preparation conditions.
“This is a pre-emptive strike,” says Glass. “We want to find out if all of these new types of E. coli act the same way as the O157 strain. If so, or if they are more sensitive to processing, then we’re OK. But if we find out that these strains end up being more resistant to heating, that means we've got a lot of work to do [to figure out how to kill them].”
Glass has been in charge of the Applied Food Safety Lab since joining the Food Research Institute (FRI) in 1985. The institute has nine core investigators who are dedicated to understanding and solving problems related to microbial foodborne pathogens and toxins. Originally founded at the University of Chicago in 1946, the institute has been at UW-Madison for the past 43 years.
Among the institute’s labs, Glass’s is unique. Crammed with pilot-scale food processing equipment—from milk pasteurizers and cheese-making vats to meat slicers and shrink-wrapping equipment—it is a place where food companies come to get help dealing with specific contamination problems. The FRI is one of few academic institutions in the nation to help businesses in this way, says Glass. The results of the current E. coli study, for instance, will be distributed widely throughout the meat industry, including the state of Wisconsin, which is home to 488 meat processors and one of the largest producers of pepperoni in the nation.
The food-processing equipment allows Glass to make a wide variety of processed meats and cheeses just as the food industry would. Except for the nasty microbes they contain, the lab’s products are indistinguishable from comparable items available on grocery store shelves.
“We’re able to make foods with contamination that mimic what might happen in the real world, and because it’s more representative of what would happen in the real world, we’re giving people more accurate results,” says Glass. “It’s a shorter distance from the basic science to the application in the real world. That's where we are. We’re that bridge.”
That is a big reason why the GMA chose UW-Madison lab to run the current E. coli study. Originally, GMA scientists had considered doing the project in-house, but they quickly realized this wasn't an option. “First off, we don’t have a smoke house, and you can’t do pepperoni without one,” says Elena Enache, a GMA microbiologist who spent the better part of 2 weeks in Madison this summer working elbow-to-elbow with Glass’ team. “At the FRI lab, we mimicked the whole process. Everything was done like in the pepperoni industry.”
It also didn’t hurt that Glass ran the original E. coli O157:H7 safety study in fermented meats in the early 1990s, and that the FRI team subsequently developed the processing techniques that are still used today to kill O157:H7 in fermented meats.
Glass claims she hasn't had a single boring day over the years. She has worked with a long list of companies, food products and pathogenic bacteria, calling upon her FRI colleagues to help whenever it made sense. Most projects involve testing the safety of new product formulations or re-evaluating products when new pathogens crop up. In recent years, Glass has been involved in a big push to discover natural antimicrobials that can compensate for the salt—a natural microbe-killer—that’s removed from low-sodium processed meats. “We go where there’s the greatest need,” says Glass, “and that’s a shifting target all the time.”
At present, the FRI has more than two-dozen dues-paying industry members that help guide the institute’s research agenda, including Wisconsin's Johnsonville Sausage, Jones Dairy Farm, Sargento Foods and Schreiber Foods. But the institute is open to research projects proposed by members and nonmembers alike. On more than one occasion, a project has kept a business from failing. Some have helped save lives.
In one particularly fruitful collaboration, the FRI collaborated with Oscar Mayer to show that adding sodium lactate to processed meats was a safe way to prevent the growth of Clostridium botulinum, the bacterium that causes botulism, and, more recently, Listeria, a deadly bacterium that thrives in these products at refrigerator-temperature.
“Now most processed meat products contain sodium lactate, and you can say that is because of a combination of work between FRI and Oscar Mayer,” says Larry Borchert, who was director of central research and regulatory affairs at Oscar Mayer from 1980 until his retirement in 1996, and oversaw Oscar Mayer’s role in the project.
While Glass is particularly proud of this project, it’s just one of many that have helped her lab fulfill its mission over the years.
“We are here to help food companies make their food products safe for the consumer,” says Glass. "We really do work together for a common goal, which is public health.” ♦
Nicole E. Miller, College of Agricultural and Life Sciences Communication Program, University Wisconsin-Madison. Ms. Miller can be contacted at nemiller2@wisc.edu.
Food Print—Make Green Count
By Sal Rastegar
Although being a vegetarian is less taxing on a piece of land where food is harvested and grown, eating a complete vegetarian diet is not efficient for most people. To meet the demands of the public, food producers think and weigh the factors of yield, point of diminishing returns, seeds and feed, transportation, philosophical differences in human diet and the technology required to produce food for the human race.
A Cornell study showed that if the city of New York were to go on a low-fat, vegetarian diet, the farms around it could support 50% of the population’s food needs, but on an animal-based, high-fat diet, only 22% of the population’s food requirements could be sustained by its meat producers. The study further explains that if the same number of calories were to be consumed per person per year on a vegetarian diet versus an animal-based diet, the vegetarian diet could be sustained by a mere one-half acre of land, compared to the 2.1 acres needed to support the animal-based diet. The conclusion of the researchers was that the most efficient diet is actually one that married the two, as raising livestock makes productive use of less fertile ground that is unsuitable for growing crops. Food print is the term coined by the researchers at Cornell to describe amount of land needed to supply one person’s nutritional needs for a year.
The world population is growing by an estimated one-half billion people every decade, and potential agriculture land is being lost to housing and development. It is clear that the role of food print will become crucial to both the availability and quality of the world food supply in the next two decades, especially considering things such as water scarcity and availability in politically volatile regions of both the Middle and Near East.
The fact that our planet is becoming overpopulated because of medical breakthroughs and advances in sanitary living, education and cultural beliefs is undeniable. The overfeeding of the first world and malnutrition of the third world are cold realities that many see and know but do not like to face. Ironically, the malnourished population keeps on growing, due to a large part to the biological reason of survival.
The Foot Print Standards Organization study shows that the earth is overburdened by 1.3 times its capacity to truly sustain itself environmentally and to sustain its inhabitants. Many feel that eating locally is the main instrument to offset the large food print that has become common, but there is more to the picture, such as how much and where fertile land is available and the basic economy of supply and demand. In addition, the palates of many consumers are becoming increasingly complex for exotic foods.
There are a variety of food authorities, non-governmental organizations, regulators and associations out there both nationally and internationally, including the U.S. Department of Agriculture, the U.S. Food and Drug Administration and its food code, the Conference for Food Protection and others, who are working to solve food-related problems, including that of food safety, for us. But to keep things straight as to who does what and to what end and also where these functions might overlap is quite a task. Additionally, the politics behind food distribution and safety, food overproduction and underproduction, food subsidies, organically grown foods, animal welfare, antibiotics and hormones used in livestock, farmers’ markets, third-party certifiers and more can add to the confusion and confound the solving of sizeable problems. Now that you are aware of the complexities of food-related issues, let’s dig a little deeper into our food print.
According to the Global Footprint Network, the ecological foot print (EF) is a measure of human demand on the earth. It compares human demand with the planet’s ecological capacity to regenerate, representing the amount of biologically productive land and sea area needed to regenerate the resources that a human population consumes and to absorb and render harmless the corresponding waste. In 2005, EF (or humanities use of ecological services) was 1.3 times faster than the Earth could renew them. Carbon dioxide was the one greenhouse gas chosen to be the main indicator of our foot print. So the goal of ecologic repair has focused on carbon offset, carbon sink and carbon sequestration.
There are many ways to offset carbon, including paying an organization to do such things as plant trees, also known as buying carbon credits. Carbon sink is achieved by such man-made products as concrete, which naturally absorbs carbon dioxide, and sequestration is the technology of injecting the elements into oceans or deep into the ground to buy time for technology and our habits to catch up with our production of greenhouse gases. The goal is to bring this all-important indicator, the greenhouse gases, under control. The mechanisms are varied, as mentioned above, for the free market to take its course, and for both legislation and the voluntary actions of people and organizations to do the right thing and create a positive reputation in a market that seems to demand it.
For us to produce and deliver the food we require, tractors, combines, trucks, trains, warehouses, farms, manufacturers, grocery stores, restaurants, refrigeration, food safety technologies, research and development, regulations and education must work in concert. All of these activities take energy; most are produced and brought to us by traditional fossil fuels that are largely responsible for our contribution to the carbon foot print.
Down-sizing our food print is both the economical and ecological key for the betterment of our lives on our planet. Researchers, scientists, regulators and other parties are still determining complex human behaviors and trying to solve this problem by reaching for the multidisciplinary knowledge of social psychologists, economists, food producers, political forces and engineers to harness the combined energy of human will and habitat. The solution is out there but how we get to it and what systems we imagine, concoct and eventually choose are what should excite us all to solve it. ♦
Sal Rastegar is the founder of Make Green Count (www.makegreencount.com) and a food safety and environmental safety consultant. He specializes in the green industry (GreenROI), environmental management, the hospitality industry, regulatory workshops, and online training. He can be reached at SRastegar@MakeGreenCount.com.
NEWS:
D-FENS: Army's Award-winning Chloride Dioxide Sanitizer Techology
Food safety experts from the Natick Soldier Research, Development and Engineering Center (NSRDEC) have invented D-FENS, the disinfectant-sprayer for foods and environmentally friendly sanitation with potential applications of sanitizing food processing/handling equipment and food preparation areas in battlefield kitchens using the “green” technology of chlorine dioxide to protect the environment.
D-FENS is a handheld, collapsible, plastic spray-bottle that mixes dry precursors with available water and controllably generates chlorine dioxide at point-of-use and on-demand. The compact configuration is easily transportable to reduce logistics and the volume of trash entering landfills.
With guidance from DoD Tech-Link, the D-FENS technology was commercially licensed in May 2009 and is currently available as a commercial product, offering tremendous savings in time, convenience and environmental protection compared to conventional sterilants. The Army recognized the accomplishments of this inventive team of NSRDEC scientists with a 2009 Research and Development Achievement Award for proven scientific and technical excellence. ♦
Nomination Period Opens for Frozen Food Foundation Freezing Research Award
The Frozen Food Foundation has announced that nominations are being accepted for the Frozen Food Foundation Freezing Research Award, presented in conjunction with the International Association for Food Protection (IAFP).
The award honors an individual, group or organization for preeminence in and outstanding contributions to the field of research impacting food safety through freezing. This is the first such award presented by the Frozen Food Foundation.
The IAFP will be receiving award nominations through February 16, 2010. Award nomination forms and instructions for submitting nominations for the Freezing Research Award can be found on-line at www.foodprotection.org and www.frozenfoodfoundation.org. The award winner will be announced at the 2010 IAFP Annual Meeting in August in Anaheim, CA. The recipient will receive a plaque and a $2,000 honorarium sponsored by the Frozen Food Foundation. ♦
Pilgrim's Pride Completes Reorganization
Pilgrim’s Pride Corporation has emerged from Chapter 11 bankruptcy protection after a 13-month restructuring. The reorganized company’s common stock began trading December 29, 2009 on the New York Stock Exchange under the symbol “PPC.”
"Pilgrim’s Pride today begins a new chapter as a market-driven company clearly focused on delivering the highest levels of service, selection and value to our customers as efficiently as possible,” said Don Jackson, president and chief executive officer. “Over the past 13 months, we have made significant improvements across our organization aimed at positioning Pilgrim’s Pride to respond quickly to the needs of the market. Those changes have touched every aspect of our business, from supply chain and operations to sales and marketing. Thanks to the commitment and support of our 41,000 employees and 4,500 growers, Pilgrim’s Pride today is a stronger, leaner company with a growing customer base, improved capital structure and a culture built on results and accountability. We are very excited about the strategic opportunities available with JBS [USA Holdings Inc.] as our majority shareholder and we look forward to generating sustained, profitable growth in the future.”
According to Winston Mar, managing director with CRG Partners, the financial and restructuring advisors to Pilgrim’s Pride, “Pilgrim’s Pride is a unique restructuring. If you look at most bankruptcies today, they usually involve a 363 sale, adjusting the balance sheet and never actually changing how the company operates. This is a great example of a true turnaround, with value restored to stakeholders. Pilgrim’s Pride has emerged as a stronger, leaner competitor. With its improved capital structure, changed product mix and leaner operations, it will be a true force among its competitors.” ♦
PRODUCT SPOLIGHTS:
Dionex Releases a Universal Detector for Your Food and Beverage Needs
Dionex Corporation is pleased to release the industry-leading Corona® ultra™ Charged Aerosol Detector for the Dionex UltiMate® 3000 RSLC systems. Charged Aerosol Detection (CAD) has broad applicability across a wide array of food and beverage applications. The Corona ultra detector can detect non-volatile analytes with a response independent of chemical structure. It is ideal for lipids where the wide variety of structures and varying UV response present an analytical challenge. With integration into the UltiMate system, these capabilities are now available in an advanced UHPLC system.
Corona ultra detectors and Ultimate 3000 RSLC systems are an ideal combination for throughput, resolution and universal detection. ♦
Dionex Corona CAD Website
EAT Here—Idaho Technology
Idaho Technology is an established industry leader in the fields of fast PCR, Real-time PCR and Hi Res Melting, and is committed to accurately and timely identifying deadly foodborne pathogens such as Salmonella, E. coli O157:H7, Listeria monocytogenes, Campylobacter, Clostridium botulinum and avian influenza with our high-speed, PCR-based Food Security System. Built upon LightCycler® technology, the R.A.P.I.D. ® LT Food Security System combines rapid air thermocycling and a real-time fluorimeter to reliably test food and environmental samples The system is Easy, Accurate, and Timely™ (EAT) and designed to Make Food Safe™. ♦
Idaho Technology Website
