In Agricultural Research Service News
March 31, 2005
New Sensory Testing Facility Open
New Agricultural Research Service (ARS) food processing and testing facilities in Beltsville, Md., will make it easier for scientists and others to evaluate the safety and quality of meat products. Two years in development, the new sensory testing facility at the ARS Food Technology and Safety Laboratory houses 10 testing booths. Each one includes a computer so trained panelists can offer quick and efficient feedback to researchers. The laboratory scientists look for ways to tenderize and reduce the amount of pathogenic and spoilage microbes on whole muscle meats and processed meats, such as hams and sausages. Hydrodynamic pressure processing (HDP) and other pressure processing methods are being evaluated to achieve these goals. HDP has been shown to be successful in tenderizing whole muscle meat, but its effectiveness in processed meat products is unknown. To test meats for texture, juiciness and flavor, sensory testing panels are convened. Some are more general in nature, testing for personal observations of flavor, juiciness, etc. Other panels, called technical descriptive panels, are more sophisticated, requiring extensive training to allow panelists to quantify those perceptions. New studies are underway to evaluate pressure technologies in the role of improving the quality and shelf-life of meat products. Use of the new equipment and sensory testing facilities will assist the scientists in determining the value-added capabilities of these technologies. ARS is the U.S. Department of Agriculture's chief scientific agency.
More Forage, But Less Filling
Continued elevated carbon dioxide concentrations in the atmosphere may reduce forage quality among the world's grasslands and lead to reduced weight gain among animals. So say ARS scientists, who conducted a five-year study on native shortgrass prairie in northern Colorado. To simulate elevated atmospheric carbon dioxide conditions and make comparisons, the scientists used six open-top chambers. Each chamber contained more than 25 different plant species, but was dominated by three perennial native grass species. Three of the chambers were infused with ambient air containing about 360 parts per million (ppm) carbon dioxide to model present atmospheric conditions. The other three chambers were infused with ambient air that had been injected with pure CO2 to double the amount of carbon dioxide to 720 ppm. The scientists found that forage quality declined in all three dominant grasses under the elevated carbon dioxide conditions, due largely to lower tissue nitrogen content. Further, they found that production of the least desirable of the three dominant grasses, Stipa comata (needle-and-thread grass), significantly increased under elevated CO2, while production in the two higher-quality grasses remained unchanged. Atmospheric concentrations of carbon dioxide have been rising steadily during the last 150 years. The compound is considered a major greenhouse gas because of its ability to trap heat near the Earth's surface.
Food-Grade Starch Put to New Industrial Use
A technique for changing the water repellency of plastic films using coatings of steam-jet-cooked starch has been developed by Agricultural Research Service (ARS) scientists. Among the reasons for using this process is to improve plastic's retention of water-based dyes and printing inks, such as those used on food labels, as well as to reduce buildup of static charge. Commercial polymers such as polyethylene are hydrophobic, or water-repelling, until rendered otherwise (hydrophilic) with chemical reagents. But coating such plastics with soluble starch -- prepared by steam-jet cooking -- could offer a cheaper, easier and safer alternative. ARS scientists have shown in studies that tiny particles of starch comprising the one-micrometer-thick coating hold water in place, preventing it from beading and rolling off the plastic's surface. And if a film of polyethylene is thin enough, the coating will temporarily change the film's shape when the coating dries. The scientists are hoping the hydrophilic starch coating will be used in making plastic films more water-friendly or by another novel application. One possible use: Preventing the buildup of electrostatic charges, which may prove useful in plastic packaging used to wrap electronics equipment.
Technology Complements Methyl Bromide Alternative
A new type of plastic cover that helps stop chemical soil fumigants from escaping into the atmosphere could provide a timely alternative for farmers facing a ban on methyl bromide. ARS scientists in Gainesville, Fla., are studying plastic covers placed over raised beds where vegetables and strawberries are grown. Fumigants applied to the soil are trapped underground by the plastic, controlling pests under the soil surface. One type of plastic cover, called virtually impermeable film (VIF), contains a central, gas-impermeable layer designed to curb soil fumigant from escaping into the atmosphere. ARS is studying environmentally safe alternatives to methyl bromide as a soil fumigant for crop protection. VIF alone isn't intended to serve as a replacement for methyl bromide, according to researchers, but would allow growers to use lower levels of fumigants that are more environmentally friendly than methyl bromide. VIF can retain alternative soil fumigants at higher concentrations for longer periods in soil than standard high-density polyethylene film now used in vegetable and strawberry production. Use of methyl bromide is due to be phased out in developed nations because it was found to deplete the Earth's ozone layer.
Quenching Plants' Thirst
Below ground, imagine having a refreshing drink of water brought to you every time you wanted. That happens to thirsty plants irrigated with what's known as a subsurface drip irrigation system. This environmentally friendly technology employs an underground network of sturdy, flexible black tubing to carry water to plant roots, exactly where they need it the most. About a decade ago, scientists with ARS's Water Management Research Unit extensively tested subsurface drip irrigation of tomatoes, cotton and corn. Today, their investigations still remain among the most comprehensive of their kind, documenting that the below-ground systems can provide higher yields while, at the same time, using less water than other systems. These early findings are important: As competition for high-quality water continues to heat up between farms and cities, some growers are now taking a new look at subsurface drip. Subsurface-drip irrigation enables growers to send precise amounts of water to roots. The underground tubing also can transport fertilizers with vital nutrients - such as phosphorus and nitrogen. A buried-drip system can conserve water by allowing growers to apply it more precisely than if they were to choose some other kinds of irrigation equipment, such as overhead sprinklers. This precision helps growers avoid over-irrigating their crops. In turn, they reduce the risk that unused nutrients would be carried by irrigation water into the underground water supply -- where they might become pollutants.