Mississippi Agricultural and Forestry Experiment Station

Food Safety and Quality

Beating bacteria

Approximately 2 million individuals in the U.S. contract foodborne illnesses from Salmonella and Campylobacter. While the first line of defense against these common bacteria is safe food handling practices by processors and consumers, Chander Sharma, Mississippi Agricultural and Forestry Experiment Station researcher and assistant professor in the Department of Poultry Science, is working to rid poultry of these common bacteria before it leaves the processing plant. He, along with a team of MSU scientists, is researching the use of lauric arginate, an antimicrobial compound approved by the USDA, as a processing aid assisting in the fight against Salmonella and Campylobacter. He is evaluating the use of bacteriophage—a virus that attacks bacteria—to combat the problem as well. Read More

Curing Ham

Methyl bromide is a broad-spectrum pesticide used to eradicate ham mite infestations. However, the pesticide depletes the ozone layer and is scheduled to be phased out by 2015. In conjunction with entomologists at Kansas State University, MAFES researchers evaluated the effects of treatment with ozone, carbon dioxide, sulfuryl fluoride and phosphine on ham mite survival, volatile flavor compound concentrations and sensory quality of dry-cured hams. Under laboratory conditions, phosphine and ozone showed some potential for eradicating ham mite infestations without affecting the sensory characteristics of dry-cured ham.

Distillers' Grains as a Feed Supplement

Increased ethanol production also means increased stocks of the by-product distillers dried grains with solubles (DDGS), as well as increased interest in finding uses for the nutrient-rich grains. A MAFES study evaluated second-cycle Bovans White laying hens that were fed varying amounts of DDGS. Researchers looked at layer performance, egg characteristics and consumer acceptability. Results showed that DDGS could comprise up to one-third of a commercial layer diet without any significant detrimental effects on the production or egg characteristics of second-cycle hens. A similar study measured breast and thigh meat quality in broilers fed DDGS-supplemented diets. Overall, the diets yielded high-quality breast meat, and thigh meat quality was similar among diets containing up to 12 percent DDGS.

Dressing Ham

A Mississippi Agricultural and Forestry Experiment Station scientist in the School of Human Sciences is hamming it up with a MAFES food scientist, an entomologist at Kansas State University, and an agricultural economist at Oklahoma State University. Fashion and food have joined forces to design ham nets that will protect dry-cured ham from mites. The idea for the project began several years ago when scientists in the MSU Department of Food Science, Nutrition and Health Promotion and Kansas State University developed a food-grade, patent pending solution that successfully deters mites. Dr. Wes Schilling and Dr. Charles Freeman then had to figure out the best way to apply the solution so that it provided continuous protection to the ham. By saturating the stockings with the solution and then allowing the hams to hang in the netting, the scientists have come up with an easy application process to help dry-cured ham producers find economical alternatives to using methyl bromide that has been steadily phased out of use due to it being an ozone depleting substance. Read More

Eradicating food-borne pathogens

MAFES scientists found that X-ray treatments and natural additives, such as essential oils and citric acid, can reduce pathogens in food products, including seafood, produce, poultry, and dairy. Barakat Mahmoud, a food safety specialist at the Coastal Research and Extension Center in Biloxi, showed that X-rays improve the quality of seafood and produce while also extending their shelf life. X-ray radiation can be used to reduce concentrations of pathogenic bacteria, such as Vibrio, Campylobacter, Salmonella, and E. coli. Vibrio, a particularly dangerous pathogen found in the Gulf of Mexico and other marine environments, is a significant problem in the oyster industry. X-ray technology also proved effective at eliminating bacteria that cause food spoilage. For example, spinach irradiated with X-rays will last 30 days longer. This technology is proving its superiority over other technologies at eliminating bacteria in food products. Read More

Extending shelf life and food safety

Increasing the length of time fresh catfish fillets can spend in the supply chain would make it more feasible for processors to offer fresh, never-frozen, tray-packed products in the retail market. MAFES scientists Taejo Kim, Juan Silva, and Byron Williams tested the effectiveness of antimicrobials and antioxidants at enhancing the safety and shelf life of fresh, vacuum-tumbled catfish fillets. They found that marinating fillets with salt, an agglomerated phosphate blend, and a combination of commercially available potassium acetate and potassium lactate is an effective strategy for inhibiting growth of the bacteria that cause spoilage in refrigerated foods. Analysis by food scientist Wes Shilling revealed that this treatment enhances the sensory acceptability of fried catfish fillets. Treatment with antimicrobials did not detract from the acceptability of the marinated fillets

Front line of food safety

According to the Centers for Disease Control and Prevention, foodborne pathogens cause an estimated 47.8 million illnesses, 128,000 hospitalizations and 3,000 deaths in the U.S. each year. Taejo Kim, scientist in the Mississippi Agricultural and Forestry Experiment Station and assistant research professor in the Department of Food Science, Nutrition and Health Promotion, has discovered a way to make industry-wide testing of Salmonella, Listeria, E.coli and certain strains of Vibrio fast, easy and affordable. His rapid test kits require no analytic instruments; can detect pathogens in 24 hours or less and are extremely reliable. Additionally, the kits culture whole cells so technicians don’t have to be skilled in extracting DNA, making it easier to use than other commercial test kits currently on the market. Read More

Fruit of the Vine

MAFES scientists, Dr. Eric Stafne and Dr. Sam Chang, are working to bring a sweet treat to Mississippi's farms. Fruits such as bunch grapes, muscadines, and blackberries, are native to the state, but have not had much success in large-scale production due to disease and harvesting difficulties. Stafne's main research has been evaluating bunch grape cultivars to see how they perform in Mississippi where there is an endemic disease called Pierce's disease (Xylella fastidiosa), which infects grapes via insect transmission. Blackberry growers also face challenges, in the form of pests and genetic disorders. As for muscadines, the biggest difficulty is in production cost. However, Dr. Sam Chang's research on the health benefits of muscadines suggests that it may be worth it. Compared to other grapes, muscadines are high in antioxidant properties, and they also have several other health benefits that could make it an up-and-coming superfood. Chang's next step will be determining which portions of the grape contain the highest concentrations of ellagic acid and antioxidants. Read More

Identifying Destructive Invaders

Exotic insect species enter the United States through multiple routes, such as on wood shipping pallets, plant materials, and imported fruits and vegetables. The U.S. government sets trade restrictions to help prevent the introduction of nonnative pests, and its inspectors work at all borders to search for and confiscate materials carrying these insects. Some hidden pests do make it past inspection and move into U.S. crops. Once established, these pests can damage crops and native plant species, ultimately causing severe economic damage. Quick identification of invasive species is crucial to stopping their spread. The Mississippi Entomological Museum was recently designated as the Eastern Region Identification Center for the USDA’s Animal and Plant Health Inspection Service.

Improving food safety from production to consumption

Food scientist Byron Williams, who spent 15 years in the food-processing industry before beginning his career at Mississippi State, focuses on food safety and value enhancement in his research and through educational workshops for processors and associated agencies. In a recent project, Williams studied pork processed through “hot boning,” in which meat is removed from a carcass before chilling. He examined the effects of combining commonly used antimicrobial ingredients on the quality, bacterial content, and sensory characteristics of sausage patties made from hot-boned pork. Williams’s study found the experimental patties were acceptable in all these traits, in addition to having an extra 3 days of shelf life. Other ongoing research explores strategies for improving quality and safety of raw materials and methods used in many Southeastern food-processing plants.

Improving food safety from the farm to the processing plant

Microbiology researcher Aaron Kiess evaluates new methods of reducing poultry exposure to pathogenic bacteria, such as Campylobacter and Salmonella, which harm consumers and reduce broiler industry profits. Kiess examines how poultry house litter management can help prevent this problem. He found that bacterial concentrations are reduced and other benefits are achieved when litter is treated using a process called “windrowing,” in which litter is piled in rows down the length of a broiler house. Heat generated in the composting piles partially sterilizes the litter. Changes in other variables, such as pH, ammonia, and moisture, may also play a role in improving litter quality and need further study. Kiess also studies the role of vertical transmission, the process by which adult chickens spread bacteria to their offspring.

Poultry scientist Chander Sharma researches methods of controlling food-borne pathogens in processed chicken products. He examines the effectiveness of USDA-approved antimicrobials that reduce the number of pathogens in poultry products. These antimicrobials have the potential of improving the safety of food products. Sharma also studies natural antimicrobials, such as rosemary, sage, and oregano.

Marbling trumps thickness in steaks

Animal scientist Trent Smith examines the importance of marbling, streaks of fat within lean sections of meat. Marbling adds quality and flavor and increases the value of a cut of meat. At MSU’s Leveck Animal Research Center or South Farm, Smith studies two groups of 30 purebred Angus cattle. One group has the genes that influence marbling, while the other does not. His goal is to evaluate the cattle’s performance and analyze the impact of the marbling genes. A MAFES survey found that most consumers cited marbling as the most important attribute of rib-eye steak. Even if consumers were not willing to pay more for thick cuts, most said they would pay more for well-marbled steaks.

MSU Researchers Ask What Steak Eaters Crave

MAFES researchers recently conducted a study to gauge the public’s willingness to pay extra for thicker, heartier steaks.

The study found that most consumers did not highly value thickness. Only 23 percent of consumers listed thickness as the most important factor of a rib eye, making it only the third most important attribute. Thirty percent cited marbling as the most important attribute of rib eye, making it the most important factor tested. Thickness only defeated marbling for first place with the sirloin steaks.

The study found that even if consumers are not willing to pay more for thickness, most of them are willing to pay more for characteristics such as color and marbling. Read More

Muscadine Juice Prevents E. Coli

Finding natural antimicrobial compounds in fruit to enhance the safety of its juice is of great interest to the beverage industry because Escherichia coli, which causes foodborne illness, can survive in acidic environments for long periods. Muscadine grape is indigenous to the Southeast and contains a large variety of antioxidant phytonutrients. MAFES scientists found that red muscadine juice has natural antibacterial substances and suggest that these can be used as active antimicrobial ingredients against E. coli in nonalcoholic beverages.

Promoting easy detection of food-borne pathogens

Food scientists Tae Jo Kim and Juan Silva developed a simple test kit that can be used to detect Salmonella in food, water, and environmental samples. This unique detection mechanism consists of a single test tube that can expose the presence of Salmonella in a sample without the need for any additional equipment. The kit, which can be stored for long periods at room temperature without losing its effectiveness, is inexpensive compared with similar products. After demonstrating the effectiveness of the technology in several lab studies, the MAFES scientists optimized the Salmonella test kit to perform in industrial and laboratory settings. They received a provisional patent on the technology and are ready to implement it in a commercial setting. Salmonella is the most frequent cause of short- and long-term food-borne illness, causing about 1.4 million food poisonings in the U.S. each year.

Protecting the Surface

Of the many suspects that cause food safety issues in kitchens and food processing plants, biofilms, caused by bacteria such as Listeria monocytogenes and Salmonella, are a common culprit. MAFES scientists Dr. Ramakrishna Nannapaneni, who specializes in food science, nutrition and health promotion and Dr. Aaron Kiess, who specializes in poultry science, are taking a stand in biofilms, the growth of bacterial cells on surfaces that touch food. Through Nannapaneni and Kiess's research, they discovered that a mixture of disinfectants was far more effective than single compound disinfectants for removal of biofilms. Dr. Kiess's lab is also looking into how Salmonella survives on poultry processing equipment before and after cleaning cycles. They hope to continue research to determine how biofilm cells become denser, stronger, and spread as well as what mechanisms govern cross-resistance. By discovering this, they hope to figure out how these tough biofilms can be eradicated to enhance food safety. Read More

Spreading Kudzu

Kudzu was introduced in the U.S. in 1876 and now grows more prolifically in the South than anywhere else in the world. Kudzu is an edible plant from the legume family, thus all parts of the kudzu plant are edible. A MAFES study was conducted to determine consumer acceptability of kudzu jelly and dip products through sensory testing. Consumer acceptance of both products was favorable.

Stressed Out

Stress can take a toll on farm-raised catfish and may also affect the end product. That's why MAFES scientists, Drs. Peter Allen and Wes Schilling, have spent five years studying the impact stress has on catfish from farm to table and fingerling to fillet. Environmental stressors included aspects of water quality, such as temperature and dissolved oxygen and sequential stressors, such as stressors in the sock (a netted enclosure) and during hauling. The stressed fish didn't eat as much or grow as fast, which resulted in smaller fillets. However, the researchers were able to determine that stress did not seem to impact the end product besides the size of the fillets. The researchers then established best practices for producers based on the research. These recommendations included minimizing harvest at elevated temperatures, reducing fish densities in hot summer conditions, and minimizing time in the sock and time from transport to processing.Read More