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United States Department of Agriculture

Agricultural Research Service

Food & Nutrition Research Briefs, April 2011

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

April 2011



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Contents

Healthy Plant Sterols: A Daily "Drip" is Best

Tactics to Safeguard Catfish and Tilapia Fillets from Foodborne Pathogens Explored

Blueberries Help Fight Artery Hardening, Lab Animal Study Indicates

Scientists Produce Palatable Gluten-Free Bread

Got Fish? Nutrition Studies Explore Health Benefits

Tangerine Tomatoes Surpass Reds in Preliminary Lycopene Study

Ultraviolet Light Boosts Carrots' Antioxidant Value

Successful Tech Transfer Leads to More Hawaiian Exports

Keeping In-Demand Smoked Salmon Safe to Eat

Scientists Release First Cultivated 'Ôhelo Berry for Hawaii


Healthy Plant Sterols: A Daily "Drip" is Best

An Agricultural Research Service (ARS)-supported study has found that blood plasma low-density lipoprotein (LDL or "bad" cholesterol) is lowered most when plant sterols are consumed in smaller amounts more often throughout the day, rather than in one large amount each day. Among a volunteer group that received plant sterols three times per day, measures of LDL cholesterol decreased by 6 percent, and this decrease was attributed to a substantial reduction in cholesterol absorption.

Details

For details, contact: Alice H. Lichtenstein, (617) 556-3127, Cardiovascular Nutrition Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Mass.

Photo: Enriched margarine-based products marketed to lower cholesterol.
Low-density lipoprotein (LDL or "bad") cholesterol is lowered most when plant sterols are consumed in small amounts throughout the day rather than in one large amount each day.

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Photo: Blueberries. Link to photo information
A new ARS-funded study in mice has provided the first direct evidence that blueberries may help fight atherosclerosis, also known as hardening of the arteries.

Blueberries Help Fight Artery Hardening, Lab Animal Study Indicates

Blueberries may help fight atherosclerosis, also known as hardening of the arteries, according to results of a preliminary Agricultural Research Service (ARS)-funded study with laboratory mice. The research provides the first direct evidence that blueberries can help prevent harmful plaques or lesions, symptomatic of atherosclerosis, from increasing in size in arteries. Lesion size, measured at two sites in the aorta (the artery leading from the heart), was 39 and 58 percent less than that of lesions in mice whose diet did not contain blueberry powder.

Details

For details, contact: Xianli Wu, (501) 364-2813, ARS Arkansas Children's Nutrition Center, Little Rock, Ark.

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Got Fish? Nutrition Studies Explore Health Benefits

Ongoing Agricultural Research Service (ARS) studies are helping uncover new details about how fish-oil components help protect us from chronic diseases. An 8-week test with 50 laboratory mice indicated that a specific omega-3 fatty acid from fish oil, called DHA (docosahexaenoic acid), protected the animals against two harmful side effects of a different fatty acid, CLA, found in some dietary supplements as trans-10, cis-12 CLA: CLA-induced insulin resistance and CLA-induced non-alcoholic fatty-liver disease. In contrast, another omega-3 fatty acid from fish oil, EPA (eicosapentaenoic acid), offered only partial protection against CLA-induced non-alcoholic fatty liver disease, and provided no protection against insulin resistance. In a literature review, the scientists indicate that findings reported in the past decade have been inconsistent in regard to the effects of EPA and DHA on insulin resistance in human volunteers.

Details

For details, contact: Darshan S. Kelley, 530-752-5138, Immunity and Disease Prevention Research Unit, ARS Western Human Nutrition Research Center, Davis, Calif.

Cooked salmon fillets with apple slices on a grill.
Ongoing studies by ARS are helping to uncover new details about how omega-3 fatty acids—common in fish like salmon—may help protect people from chronic diseases such as diabetes. Photo courtesy of Omaha Steaks.

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Photo: Carrot slices being exposed to UV-B ultraviolet light. Link to photo information
Sliced carrots exposed to UV-B ultraviolet light can have higher levels of antioxidants.

Ultraviolet Light Boosts Carrots' Antioxidant Value

Exposing sliced carrots to UV-B, one of the three kinds of ultraviolet light in sunshine, can boost the antioxidant activity of the colorful veggie, based on results of preliminary studies by Agricultural Research Service (ARS) scientists. The carrot study results suggest that a moderate, 14-second dose of UV-B can boost fresh, sliced carrots' antioxidant capacity by about 3-fold. The dose is energy-efficient and does not significantly heat or dry the carrots.

Details

For details, contact: Tara McHugh, (510) 559-5864, Processed Foods Research Unit, ARS Western Regional Research Laboratory, Albany, Calif.

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Keeping In-Demand Smoked Salmon Safe to Eat

Agricultural Research Service (ARS) scientists are helping ensure that the smoked salmon that's always a hit at festive gatherings also is always safe to eat, including the development of a first-of-its-kind mathematical model that food processors and others can use to select the optimal combination of temperature and concentrations of salt and smoke compounds to reduce or eliminate microbial contamination of the product. The researchers determined that every 9 degree Fahrenheit increase in temperature resulted in a 10-fold increase in rates of inactivation of Listeria. They used this and other data from the study to create the mathematical model.

Details

For details, contact: Andy (Cheng-An) Hwang, (215) 233-6416, Residue Chemistry and Predictive Microbiology Unit, ARS Eastern Regional Research Center, Wyndmoor, Pa.

Photo: Food technologist and technician study the effect of smoking temperature on survival of Listeria monocytogenes on smoked salmon. Link to photo information
Food technologist Andy Hwang and technician Stacy Raleigh study the effect of smoking temperature on survival of Listeria monocytogenes on smoked salmon.

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Photo: ARS food microbiologist Kathleen Rajkowski places catfish fillets into a UV treatment device. Link to photo information
Food microbiologist Kathleen Rajkowski places a frozen catfish fillet into a device for surface decontamination by pulse UV treatment.

Tactics to Safeguard Catfish and Tilapia Fillets from Foodborne Pathogens Explored


An Agricultural Research Service (ARS) microbiologist has conducted the first-ever study to identify the dosages of ionizing radiation needed to effectively reduce the pathogen Listeria monocytogenes in tilapia and catfish fillets. In experiments with both frozen and thawed tilapia and catfish, the fillets were artificially inoculated with L. monocytogenes. Then the amount of ionizing radiation needed to reduce the pathogen's population by 90 percent was determined. The dosages needed to achieve that level of safety were nearly the same for both kinds of fish. The results were similar to those that reduce Listeria in ground beef. Other tests examined the effectiveness of ultraviolet (UV) light in combating foodborne pathogens. A solution of Shigella sonnei was applied to the surface of frozen and fresh tilapia, then the samples were exposed to medium-intensity UV light. The treatment resulted in a 99 percent reduction of the pathogen on the frozen fillets, but did not kill S. sonnei on the fresh tilapia. However, exposing the fresh fillets to pulsating beams of high-intensity UV light reduced the pathogen by 99 percent.

Details

For details, contact: Kathleen Rajkowski, (215) 233-6440, Food Safety and Intervention Technologies Unit, ARS Eastern Regional Research Center, Wyndmoor, Pa.

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Scientists Produce Palatable Gluten-Free Bread

By removing a certain amount of fat from a corn protein called zein, Agricultural Research Service (ARS) scientists have been able to produce high-quality gluten-free bread dough more similar to wheat dough, as well as free-standing, hearth-type rolls that resemble wheat rolls. Millions of Americans affected by celiac disease are unable to digest gluten, a protein in flour from grains such as wheat, barley and rye. The researchers previously had made gluten-free pan bread from other grains, but they couldn't make free-standing rolls because the dough spread out too much.

Details

For details, contact: Scott Bean, (785) 776-2725, Grain Quality and Structure Research Unit, ARS Center for Grain & Animal Health Research, Manhattan, Kan.

Photo: Assorted loaves of bread. Link to photo information
ARS scientists have developed a new process to produce gluten-free bread from corn flour that produces higher quality bread that is closer to the texture of conventional bread like those pictured here.

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Photo: Tangerine tomatoes in bins.
Tangerine tomatoes might be a better source of lycopene than traditional red tomatoes.

Tangerine Tomatoes Surpass Reds in Preliminary Lycopene Study

A one-month study led by Agricultural Research Service (ARS) scientists in California has provided new evidence to suggest that, ounce for ounce, tangerine heirloom tomatoes might be a better source of a powerful antioxidant called lycopene than are familiar red tomatoes. The difference lies in the forms of lycopene that the two tomato types provide. The trans-lycopene form, or isomer, makes up most of the lycopene in common red tomatoes. In contrast, most of the lycopene in tangerine tomatoes is tetra-cis-lycopene.

Details

For details, contact: Betty J. Burri, (530) 752-4748, Immunity and Disease Prevention Research Unit, ARS Western Human Nutrition Research Center, Davis, Calif.

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Successful Tech Transfer Leads to More Hawaiian Exports

Hawaiian growers can now export more fruits and vegetables to the U.S. mainland, thanks to studies by Agricultural Research Service (ARS) scientists. Strict quarantine restrictions and phytosanitary measures have been in place to ensure agricultural pests like fruit flies don't invade the mainland along with imports from Hawaii like papaya, rambutan, longan, dragon fruit and purple-fleshed sweet potato. The ARS scientists found that a generic dose of 150 grays (Gy) of radiation is suitable for controlling the three species of Tephritid fruit flies found in Hawaii. They also demonstrated that a generic dose of 400 Gy is broadly effective against many other pests. These results contributed to approval by USDA's Animal and Plant Health Inspection Service (APHIS) of using generic doses of radiation for treatment of Hawaiian produce. The ARS scientists also examined product quality after irradiation. Those tests helped establish the maximum dose levels the fruit and vegetables could withstand while ensuring consumers receive a high-quality product.

Details

For details, contact: Peter A. Follett, (808) 959-4303, Tropical Crop and Commodity Protection Unit, ARS U.S. Pacific Basin Agricultural Research Center, Hilo, Hawaii.

Photo: Slices of dragon fruit on a plate. Inset: Whole dragon fruit.
Dragon fruit, Hylocereus sp., a delicious tropical fruit gaining popularity in the continental United States.

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Photo: Ohelo berry, a popular native Hawaiian fruit.
'Ôhelo berry, a popular native Hawaiian fruit. Photo courtesy of Francis T.P. Zee, ARS.

Scientists Release First Cultivated 'Ôhelo Berry for Hawaii

The first cultivar of 'ôhelo berry, a popular native Hawaiian fruit, has been released by Agricultural Research Service (ARS) scientists and their university and industry cooperators. 'Ôhelo (Vaccinium reticulatum Smith) is a small, native Hawaiian shrub in the cranberry family, commonly found at high elevations on the islands of Maui and Hawaii. As people scour the landscape to harvest this wild, delectable berry for use in jam, jelly and pie filling, they unfortunately disrupt the fragile habitats where this plant grows. The ARS scientists are now evaluating 'ôhelo for small farm production and ornamental use.

Details

For details, contact: Francis Tso Ping Zee, (808) 959-5833, ARS Tropical Plant Genetic Resources and Disease Research Unit, Hilo, Hawaii

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Last Modified: 4/18/2011