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United States Department of Agriculture

Agricultural Research Service

Food & Nutrition Research Briefs, October 2011

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

October 2011



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Contents

Does Grilling Kill E. coli O157:H7?

Blueberries Help Lab Rats Build Strong Bones

Mammary Gland Development of Blueberry-Fed Lab Animals Studied

E. coli Can Survive in Streambed Sediments for Months

New Freeze-dry Method Good for Processing Fish

New Flavors Emerge from Peruvian Cacao Collection Trip

Researchers Develop Fully Cooked Food-Aid Product

ARS Nutrition Resources on the Internet

Scientists Help Keep Salad Mixes Safe

ARS Human Nutrition Laboratories


Does Grilling Kill E. coli O157:H7?

Agricultural Research Service (ARS) scientists are learning more about the movement of Escherichia coli into "subprimals," the meat from which top sirloin steaks are carved. The focus is on what happens to the E. coli when subprimals are punctured as part of the tenderization process, and the effect of cooking on survival of those microbes. In early studies, the researchers applied various levels of E. coli O157:H7 to the "lean-side" surface of subprimals and ran the meat, lean side up, through a blade tenderizer. In general, only 3 to 4 percent of the E. coli O157:H7 cells were transported to the geometric center of the meat. Next, the group applied E. coli to the lean-side surface of more subprimals, put the meat through a blade tenderizer, then sliced it into steaks and cooked the meat on a commercial open-flame gas grill. The findings confirmed that if a relatively low level of E. coli O157:H7 is distributed throughout a blade-tenderized top sirloin steak, proper cooking on a commercial gas grill is effective for eliminating the microbe.

Details

For details, contact: John B. Luchansky, (215) 233-6620, Food Safety and Intervention Technologies Unit, ARS Eastern Regional Research Center, Wyndmoor, Pa.

Photo: A sirloin steak is being turned over on a flaming grill. Link to photo information
ARS studies with sirloin steaks show the effect that grilling has on the survival of E. coli O157:H7 that has been moved—by mechanical tenderization—from the meat's surface to its interior.

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Photo: Blueberries. Link to photo information
Adding blueberries to the feed of female lab rats during pregnancy and nursing improved the mammary gland health of their offspring, according to initial results of an ARS-funded study.

Mammary Gland Development of Blueberry-fed Lab Animals Studied


Agricultural Research Service-funded studies of mammary gland development in laboratory rats fed blueberries or other foods of interest may aid breast cancer research. In an early study, it was determined that several indicators of rat mammary gland health were improved in the offspring (pups) of mothers (dams) that had been fed 5 percent blueberry powder in their rations during pregnancy and during the weeks that they nursed their pups.

Details

For details, contact: Rosalia C. M. Simmen, (501) 364-2847, ARS Arkansas Children's Nutrition Center, Little Rock, Ark.

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New Freeze-dry Method Good for Processing Fish

A quicker freeze-dry technique used to process salmon cubes could potentially add value to fish components considered to be less appealing. The new freeze-dry method, which requires less energy and processing time, was developed by Agricultural Research Service (ARS) scientists in collaboration with scientists at the University of Alaska-Fairbanks. The scientists created a process that took only nine hours, raising the temperature from minus 40 degrees Fahrenheit to 32 degrees Fahrenheit. Traditional processing can take 20 hours or more. The new method removed 97 percent of the moisture from fillets of Alaska's most abundantly harvested Pacific salmon species—pink, sockeye and chum. The freeze-dried salmon cubes maintained their original color, rehydrated quickly and shrank less in a shorter period of time than food processed by traditional freeze-drying.

Details

For details, contact: Peter Bechtel, (907) 486-1531, ARS Subarctic Agricultural Research Unit, Fairbanks, Alaska.

Cubes of freeze dried salmon in a garden salad: Link to photo information
ARS researchers and their collaborators have developed a quicker way to freeze-dry salmon that maintains color, rehydrates quickly and shrinks less, expanding options for adding seafood to the diet, such as these salmon cubes.

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Photo: Instant Corn Soy Blend as extruded, milled into a powder and reconstituted into porridge. Link to photo information
ARS scientists have developed Instant Corn Soy Blend, a fully cooked food product that can be extruded, milled into a powder and then reconstituted with sanitized water into porridge.

Researchers Develop Fully Cooked Food-Aid Product


Agricultural Research Service (ARS) scientists have helped develop a fully cooked food-aid product called Instant Corn Soy Blend to supplement meals, particularly for young children. A team of USDA scientists, program managers, policy administrators, and international aid agencies worked for more than a decade to develop this new emergency meal to help in humanitarian food aid efforts. The new food product uses the same type of machines that make fully cooked puffed snacks and cereals. The crunchy, fully cooked product exits the extruder through an opening at the end of the machine in less than two minutes. The Instant Corn Soy Blend is then crushed and milled to form the ration. The ARS technology significantly enhances the uniform distribution of added vitamins and minerals in a supplemental food ration that can be efficiently delivered overseas for mass-feeding of young children and others.

Details

For details, contact: Charles Onwulata, (215) 233-6497, Dairy and Functional Foods Unit, ARS Eastern Regional Research Center, Wyndmoor, Pa.

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Scientists Help Keep Salad Mixes Safe

Innovative studies by Agricultural Research Service (ARS) scientists are providing new information about the impressive array of genes that a major foodborne pathogen, E. coli O157:H7, calls into action when attempting to colonize leaves of fresh-cut lettuce. Mechanical cutting of lettuce leaves into large pieces or shredding of leaves into narrow strips, like those in taco filling, breaks the lettuce cells, which exude carbohydrates that E. coli can use as a source of energy. But injured cells can also leak natural compounds such as antimicrobials that are problematic for the pathogen. A study with romaine lettuce showed that E. coli can adapt quickly when exposed in lab tests to the contents of broken lettuce leaf cells. Using an approach known as microarray-based whole genome transcriptional profiling, the researchers determined that the pathogen uses its genetic arsenal to protect itself against not only the antimicrobial compounds, but also against oxidative stress, osmotic stress, damage to its DNA and other threats to its ability to survive and multiply.

Details

For details, contact: Maria T. Brandl, (510) 559-5885, Produce Safety and Microbiology Research Unit, ARS Western Regional Research Center, Albany, Calif.

Photo: ARS microbiologists Maria Brandl and Craig Parker study data on a computer screen to identify E. coli O157:H7 genes. Link to photo information
ARS research microbiologists Maria Brandl and Craig Parker have identified genes in Escherichia coli O157:H7 that help this foodborne pathogen colonize fresh-cut lettuce.

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Photo: Investigators Jin-Ran Chen views a rat bone with a fluorescent micrograph projected on a computer screen. Link to photo information
Compounds in blueberries helped build strong bones in laboratory rats, according to an ARS-funded study led by investigator Jin-Ran Chen.

Blueberries Help Lab Rats Build Strong Bones

Compounds in blueberries might turn out to have a powerful effect on formation of strong, healthy bones, if results from studies with laboratory rats turn out to hold true for humans. The Agricultural Research Service (ARS) studies showed that rats fed rations that contained 10 percent freeze-dried blueberry powder had significantly more bone mass than their counterparts whose rations were blueberry-free. When the researchers exposed laboratory cultures of bone-forming cells (osteoblasts) to blood (serum) from the animals, they found that serum from the blueberry-fed rats was associated with an increase in development of osteoblasts into mature, functional bone cells. The work has paved the way for new research that might reveal whether blueberries could be used in the future in treatments to boost development of bone mass and to help prevent osteoporosis.

Details

For details, contact: Jin-Ran Chen, (501) 364-2707, Skeletal Development Laboratory, ARS Arkansas Children's Nutrition Center, Little Rock, Ark.

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E. coli Can Survive in Streambed Sediments for Months

Agricultural Research Service (ARS) studies have confirmed that the presence of E. coli pathogens in surface waters could result from the pathogen's ability to survive for months in underwater sediments. Most E. coli strains don't cause illness, but they are indicator organisms used by water quality managers to estimate fecal contamination. Lab studies conducted suggested that non-pathogenic strains of E. coli can survive much longer in underwater sediments than in the water column itself, and provided the first published evidence that E. coli can overwinter in the sediment. The results also indicated that the pathogens lived longer when levels of organic carbon and fine sediment particles in the sediment were higher. In addition, when organic carbon levels were higher, water temperatures were less likely to affect the pathogens' survival rates.

Details

For details, contact: Yakov Pachepsky, (301) 504-7468, Environmental Microbial and Food Safety Laboratory, ARS Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md.

Photo: Soil scientist Andrey Guber takes water samples from Beaverdam Creek.
ARS researchers have discovered that E. coli pathogens can survive for months in underwater sediments, which could improve computer modeling for the bacterial contamination of surface waters.

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Photo: A bar of Fortunato No. 4 chocolate, a fine-flavor product made from a new type of cacao tree identified in northern Peru. Link to photo information
New cacao types with unique flavors have been identified by ARS scientists on a collecting trip to Peru, which could one day result in specialty chocolates marketed like wine, by geographical provenance.

New Flavors Emerge from Peruvian Cacao Collection Trip

New cacao types with unique flavors that are distinctly Peruvian have been identified Agricultural Research Service (ARS) scientists. These new flavors could one day be marketed like fine wine, by geographical provenance. The ARS researchers and their Peruvian collaborators found these new cacao plants during collection expeditions in 2008 and 2009 in the Amazon Basin of Peru. The researchers are studying 342 cacao specimens collected from 12 watersheds in Peru and categorizing the DNA of the specimens.

Details

For details, contact: Lyndel Meinhardt, (301) 504-1995, Sustainable Perennial Crops Laboratory, ARS Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md.

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ARS Nutrition Resources on the Internet


USDA National Nutrient Database for Standard Reference
www.ars.usda.gov/Nutrientdata

Dietary Supplement Ingredient Database
http://dietarysupplementdatabase.usda.nih.gov/

Food Composition Resource List for Professionals
(compiled by NAL's Food and Nutrition Information Center)
http://www.nal.usda.gov/fnic/pubs/bibs/gen/foodcomp.pdf

Food and Nutrient Database for Dietary Studies
http://www.ars.usda.gov/Services/docs.htm?docid=12089

What We Eat in America
http://www.ars.usda.gov/Services/docs.htm?docid=18349

ARS Human Nutrition Research Program
www.ars.usda.gov/HumanNutrition

Functional Foods Research in ARS
www.ars.usda.gov/SP2UserFiles/Program/107/FinalFunctionalFoodsPDFReadVersion6-25-10.pdf


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Photo: Building 307C, one of the nutrition research facilities at the Beltsville Human Nutrition Research Center.
Building 307C, one of the nutrition research facilities at the Beltsville Human Nutrition Research Center.

ARS Human Nutrition Laboratories

Grand Forks Human Nutrition Research Center
http://ars.usda.gov/Main/site_main.htm?modecode=54-50-00-00

Western Human Nutrition Research Center
http://ars.usda.gov/main/site_main.htm?modecode=53-06-25-00

Children's Nutritional Research Center
http://ars.usda.gov/main/site_main.htm?modecode=62-50-00-00

Beltsville Human Nutrition Research Center
http://ars.usda.gov/main/site_main.htm?modecode=12-35-00-00

Delta Obesity Prevention Research Unit
http://ars.usda.gov/main/site_main.htm?modecode=62-51-05-00

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Last Modified: 3/6/2013
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