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United States Department of Agriculture

Agricultural Research Service

Food and Nutrition Research Briefs, July 2011

Table place setting with apple. Title: Food and Nutrition Research Briefs. Link to FNRB home page

July 2011



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Contents

E. coli an Unlikely Contaminant of Plant Vascular Systems

Keeping Oysters, Clams and Mussels Safe to Eat

Market Lighting Affects Nutrients

Don't Underestimate the Power of Herbal Teas

Blueberry's Effects on Cholesterol Examined in Lab Animal Study

Lesser Known Escherichia coli Types Targeted in Food Safety Research

Food Safety Study of Beef "Trim" Leads to Ongoing Research Collaboration

Dietary Yeast Extracts Tested as Alternative to Antibiotics in Poultry

Studies Focus on Feed Ingredient's Effects on Levels of E. coli O157:H7 in Cattle

High-Tech Approach Uses Lights, Action and Camera to Scrutinize Fresh Produce


E. coli an Unlikely Contaminant of Plant Vascular Systems

Agricultural Research Service (ARS) scientists have helped confirm that Escherichia coli is not likely to contaminate the internal vascular structure of field-grown leafy greens, which would be likely to increase the incidence of foodborne illness. There was no evidence that E. coli had become "internalized" in leaves or shoots of baby spinach plants 28 days after the plants had germinated and grown in pasteurized soil. E. coli could be detected in hydroponically-grown spinach samples, but its survival in shoot tissue was sporadic.

Details

For details, contact: Manan Sharma, (301) 504-9198, Environmental Microbial and Food Safety Laboratory, ARS Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md.

Photo: Escherichia coli.
Escherichia coli.

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Photo: Package of fresh salad greens. Link to photo information
ARS researchers have found that spinach leaves exposed to light similar to the 24-hour fluorescent light received by packages of fresh salad greens on display in grocery stores had higher levels of some nutrients than did leaves exposed to continuous dark.

Market Lighting Affects Nutrients

Spinach leaves exposed to continuous light during storage were, overall, more nutritionally dense than leaves exposed to continuous dark, according to an Agricultural Research Service (ARS) study. Researchers exposed spinach leaves to light similar to the 24-hour artificial fluorescent light received by spinach in packages located at the front of the display case. A second group was enclosed in two-layer-thick, brown-grocery-bag paper to represent the "dark treatment." The researchers found that the continuous light affected the leaves' photosynthetic system, resulting in a significant increase in levels of carotenoids and vitamins C, E, K, and B9, or folate.

Details

For details, contact: Gene E. Lester, (301) 504-5981, Food Quality Laboratory, ARS Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md.

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Blueberry's Effects on Cholesterol Examined in Lab Animal Study

Laboratory hamsters that were fed rations spiked with blueberry peels and other blueberry-juice-processing leftovers had better cholesterol health than hamsters whose rations weren't enhanced with blueberries. All of the hamsters that were fed blueberry-enhanced rations had from 22 to 27 percent lower total plasma cholesterol than hamsters fed rations that didn't contain blueberry juice byproducts. Levels of VLDL (very low density lipoprotein—a form of "bad" cholesterol) were about 44 percent lower in the blueberry-fed hamsters. Further research is needed to confirm whether the effects observed in hamsters hold true for humans.

Details

For details, contact: Wallace Yokoyama, (510) 559-5695, Processed Foods Research Unit, ARS Western Regional Research Center, Research Albany, Calif.

Photo: Hands scooping blueberries out of a bowl with blueberry pie and sundaes in the background. Link to photo information
An ARS laboratory animal study reports that eating blueberries lowered cholesterol levels in hamsters on a high-fat diet.

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Photo: Hamburger on a bun.
International collaborations on pathogen detection technologies ensure imported beef trim used to make ground beef is safe to eat.

Food Safety Study of Beef "Trim" Leads to Ongoing Research Collaboration

Agricultural Research Service (ARS) researchers examined 1,186 samples of beef "trim"—the meat that's left over after steaks and roasts have been carved from a side of beef—from the United States and from Australia, New Zealand and Uruguay, three nations that provide more than half of America's beef imports, for bacterial contamination to test current diagnostic procedures. The research had been requested because questions had been raised as to whether America's procedures for monitoring the safety of imported beef trim were adequate for detecting pathogens such as E. coli in trim. The researchers looked for contaminants such as Staphylococcus aureus, Campylobacter, Salmonella, Listeria, and near relatives of E. coli O157:H7 that can cause severe foodborne illness. Results indicated that the pathogen-monitoring procedures used in the United States today are adequate for evaluating the safety of imported beef trim.

Details

For details, contact: Joseph M. Bosilevac, (402) 762-4225, Meat Safety and Quality Research Unit, ARS U.S. Meat Animal Research Center, Clay Center, Neb.

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Photo: ARS microbiologist James E. Wells processes bovine fecal samples for microbial analysis
ARS microbiologist James E. Wells and colleagues are determining how using wet distiller's grains with solubles—an ethanol byproduct—as a cattle feed ingredient affects E. coli O157:H7 levels in the animals' manure and hides.

Studies Focus on Feed Ingredient's Effects on Levels of E. coli O157:H7 in Cattle

The pros and cons of using wet distiller's grains with solubles (WDGS)—what's left of corn after it is processed to make ethanol—as a cattle feed ingredient are being studied by Agricultural Research Service (ARS) scientists. Experiments showed that the incidence and prevalence of E. coli O157:H7 in manure, and the incidence on hides, was significantly higher for cattle whose corn-based feed included 40 percent WDGS than those whose feed did not include WDGS. In follow-up studies, the researches want to determine what causes the difference in E. coli levels, and what can be done to reduce them.

Details

For details, contact: James E. Wells, (402) 762-4174, Meat Safety & Quality Research Unit, ARS U.S. Meat Animal Research Center, Clay Center, Neb.

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Keeping Oysters, Clams and Mussels Safe to Eat

New techniques that will decontaminate clams, mussels, and oysters while protecting the mollusks' flavor, texture, and color are being explored by Agricultural Research Service (ARS) scientists. A specialized commercial procedure known as high pressure processing, or HPP, can inactivate viruses. HPP is already used commercially to pasteurize some juices and meats, and by some shellfish processors to deactivate Vibrio bacteria. But this study was the first to show that HPP also can inactivate some foodborne viruses.

Details

For details, contact: David H. Kingsley, (302) 857-6406, ARS Food Safety and Intervention Technologies Unit, Dover, Del.

Photo: Scientist examines recently harvested oysters. Link to photo information
ARS molecular biologist David H. Kingsley is testing high pressure processing to kill foodborne viruses in clams, mussels, and oysters while protecting the seafood's taste, texture, and color.

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ARS-funded researchers are checking out science-based evidence of health benefits that could come from drinking three popular herbal teas—hibiscus, peppermint, and chamomile.

Don't Underestimate the Power of Herbal Teas

The idea that herbal teas may provide a variety of health benefits is not just folklore. A survey of the research literature on the health benefits from drinking three of the most popular herbals in America—chamomile, peppermint, and hibiscus tea—found compelling science-based evidence. While there was no clinical evidence for a calming effect from chamomile tea, test-tube evidence of moderate antimicrobial activity and significant antiplatelet-clumping activity was found. In test tubes, peppermint tea has been found to have significant antimicrobial and antiviral activities, strong antioxidant and antitumor actions, and some antiallergenic potential. Based on a human clinical trial, drinking hibiscus tea was found to have lowered blood pressure in a group of pre-hypertensive and mildly hypertensive adults.

Details

For details, contact: Diane L. McKay, (781) 608-7183, Antioxidants Research Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Mass.

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Lesser Known Escherichia coli Types Targeted in Food Safety Research

In the past few years, a half-dozen emerging E. coli species, also called serogroups, have come to be known among food safety specialists as "the Big Six," namely E. coli O26, O45, O103, O111, O121, and O145. Researchers are sorting out "who's who" among these related pathogens so that the microbes can be quickly and reliably detected and identified. A group led by Agricultural Research Service (ARS) scientists has developed gene-based PCR (polymerase chain reaction) assays for each of the Big Six. With further work, the assays might be presented as user-friendly test kits for use by regulatory agencies and others. Analyses of test results also might help researchers determine whether certain strains of Big Six E. coli species cause more illness than E. coli O157:H7 does, and if so, why.

Details

For details, contact: Pina M. Fratamico, (215) 233-6525, Molecular Characterization of Foodborne Pathogens Unit, ARS Eastern Regional Research Center, Wyndmoor Penn.

Photo: Colorized scanning electron micrograph of pathogenic E. coli on a lettuce leaf. Image is shown at about 16,000 times normal size. Link to photo information
ARS microbiologist Pina M. Fratamico and her collaborators have developed gene-based PCR (polymerase chain reaction) assays to help identify and detect six newly important Escherichia coli species that are close relatives of E. coli O157:H7 (shown here at about 16,000 times normal size).

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Photo: ARS microbiologist Gerry Huff inoculates chicken embryos through the eggshell. Link to photo information
ARS microbiologist Gerry Huff is developing a dietary yeast extract that could serve as an effective alternative to antibiotics for poultry producers.

Dietary Yeast Extracts Tested as Alternative to Antibiotics in Poultry

Initial Agricultural Research Service (ARS) studies suggest that dietary yeast extract has good potential as a non-antibiotic alternative for decreasing pathogens in organic turkey production. Yeast extracts help boost the immune system's ability to kill bacteria, but there is also a downside. Yeast ramps up certain aspects of the immune response, but body weight may be decreased in some birds.

Details

For details, contact: Geraldine R. Huff, (479) 575-7966, ARS Poultry Production and Product Safety Research Unit, Fayetteville, Ark.

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Photo: ARS biophysicist Moon Kim examines apples with a new multispectral optical scanning system. Link to photo information
ARS biophysicist Moon Kim and colleagues have developed and patented a multispectral optical scanning system that can find some defects and contaminants on fresh produce at the packinghouse.

High-Tech Approach Uses Lights, Action and Camera to Scrutinize Fresh Produce

Agricultural Research Service (ARS) scientists have developed and patented an experimental, cutting-edge optical scanning system that would use two different kinds of lighting, a sophisticated camera and other pieces of equipment to scrutinize produce-section favorites like apples while they are still at the packinghouse. The system would provide, in a single image, evidence of certain kinds of defects, which could include cuts and bruises, and contaminants, which might include specks of fertilizer from orchard or field soil.

Details

For details, contact: Moon S. Kim, (301) 504-8450, ext. 245, Environmental Microbial and Food Safety Research Laboratory, ARS Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md.

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Last Modified: 7/20/2011
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