A lethal mixture of dust and heat means trouble for insects that infest food-processing plants.The dust, called diatomaceous earth (DE), is made from the fossilized skeletons of aquatic plants. To test the mixture, ARS scientists and cooperators placed confused flour beetles–one of the food-processing industry's worst insect invaders–inside a Quaker Oats treatment facility in Canada last year. The researchers dusted the area with DE using hand-held dry powder sprayers. Then they raised the indoor temperature to 120° F. This combination killed 100 percent of the beetles within one day. The heat breaks down the insect's waxy exoskeleton, and the DE absorbs the wax layers, disrupting its internal water balance. The payoff for the food industry: lower heat treatment costs and better insect control using DE and heat compared with using heat treatment alone. Both Canadian and U.S. food-processing plants have used heat treatments to kill the invading pests, but a few processors are concerned about expensive installation of new heating systems in older buildings.U.S. Grain Marketing, Production and Research Center, Manhattan, KS Alan K. Dowdy, (785) 776-2719,

dowdy@usgmrl.ksu.edu

Pigs genetically engineered with a growth factor gene may give consumers leaner pork in the future.The new transgenic pigs carry a gene for insulin-like growth factor-I (IGF-I). Produced by ARS researchers in collaboration with GeneMedicine, Inc., The Woodlands, TX, the IGF-I transgenic pigs have some of the same positive carcass composition characteristics as transgenic pigs injected with a growth hormone (GH) gene. A key difference, however, is that none of the IGF-I transgenic pigs have developed the health problems encountered earlier in the GH transgenic pigs. That's because most mammalian cells already have small amounts of IGF-I, which stimulates development of bone, muscle, nerve and organ tissues. IGF-I produced in muscle increases significantly without affecting the amount in the other tissues, making the IGF-I transgenic pigs unique. ARS scientists compared pigs with and without IGF-I to see how it affected their growth rate, feed efficiency, carcass composition and general health. They compared those results with the results obtained earlier with the GH transgenic and regular pigs. The researchers found that IGF-I helped reduce carcass fat and boost lean body mass–making those hogs worth $6 more at market than pigs without the transgene. The study also confirmed that the IGF-I pigs didn't suffer from severe health problems associated with the GH transgene. ARS scientists say this preliminary work is a first step to producing leaner pigs, but it will have to be tested on market-grade animals. The scientists' next step will be to cross IGF-I transgenic pigs with market-line hogs to see if increased levels of the hormone enhance muscle development in already lean, heavy-muscled; crossbred market hogs.Gene Evaluation and Mapping Laboratory, Beltsville, MD Vernon G. Pursel, (301) 504-8342,
vpursel@ggpl.arsusda.gov

A hand-held laser instrument that's similar to airport metal detectors can alert meat packers to unseen fecal contamination within seconds.A soiled carcass can then be sanitized before the contamination spreads. ARS and Iowa State University researchers are patenting devices that illuminate unseen fecal matter on meat. The device is adaptable to any size packing plant. Currently, the industry relies on visual inspection and culturing tests for E. coli 0157:H7. These tests, however, are time- consuming and don't reveal the presence of other harmful bacteria, such as salmonella or campylobacter. Each year, the U.S. meat processing industry slaughters 37 million cattle, 93 million hogs, 4 million sheep, 300 million turkeys and 7.8 billion chickens, valued at more than $50 billion. National Animal Disease Center, Ames, IA Mark Rasmussen/Tom Casey, (515) 239-8350,

mrasmuss@nadc.ars.usda.gov

A new computer model from ARS scientists evaluates potential risk of Salmonella infection from poultry produced by specific farm-to-table scenarios. This modeling program will help poultry companies and regulatory agencies make important food safety decisions that safeguard public health. Available at no cost on a floppy disk, the program can be used to create new models for other pathogens like E. coli and Campylobacter, and other foods including ground beef and apple cider. It is ideal for evaluating the impact of new intervention methods–such as irradiation–on the risk of foodborne disease in humans. The method can be used to evaluate the effectiveness of the new HACCP (Hazard Analysis and Critical Control Points) program that became effective in January 1998. Two major poultry producers are testing the new easy- to-use modeling system. Eastern Regional Research Center, Microbial Food Safety Research Unit, Princess Anne, MD Tom Oscar, (410) 651-6062,

toscar@umes-bird

A forced hot-air treatment designed to kill Mexican fruit flies in export-bound Texas grapefruit also protects the produce from green mold spoilage. Last year, based on ARS research, USDA regulators approved the use of a quarantine treatment of forced, moist, hot air for grapefruit in Mexfly-infested areas. In their latest lab research, the scientists inoculated grapefruit with spores of Penicillium digitatum, the fungus that causes green mold. Then they applied the forced hot air and, after four days of storage at 70° F, looked for mold. Grapefruit exposed to the 113° F quarantine treatment had between 60 and 80 percent less mold than unheated grapefruit. Forced hot air may also reduce the need for fungicides in citrus wax by boosting biocontrol agents' effectiveness. The hot air could accelerate the growth of a heat-loving biocontrol agent while inhibiting green mold from spreading. The ARS researchers are now seeking cooperators for small-scale pilot tests. 7, Crop Quality and Fruit Insects Research, Weslaco, TX Krista Shellie, (956) 565-264
kshellie@pop.tamu.edu

Bakers can make oat bread with texture almost like that of white bread by using flour milled from oats superheated with steam.Scientists found that steaming oats at 221° F for 20 minutes helped finely ground oat flour absorb the water necessary to mix dough. In baking experiments, the scientists determined that flour blends should contain no more than 10 percent oat flour to make an acceptable bread. Besides providing a specialty bread flavor and nutritional benefits, oat flour naturally slows bread from turning stale. Cereal Crops Research, Fargo, ND Douglas C. Doehlert, (701) 239-1413,
doehlert@plains.nodak.edu

Salad-bar banana slices could be just around the corner, thanks to ARS research that slows browning in the cut fruit. Bananas aren't offered in salad bars because they turn brown almost immediately after they're cut. But ARS scientists mixed citric acid and N- acetylcysteine–a common, sulphur-containing amino acid–to keep banana slices for 14 days at 40° F without browning. The treatment not only allows bananas to be marketed as fresh-cut, but also retards browning and reduces decay in fresh-cut slices of apple, pear, peach, plum, nectarine and avocado. Treated apples did particularly well, holding up for 50 days in cold storage without any change in flavor.

Horticultural Crops Quality Laboratory,Beltsville, MD J. George Buta/Harold E. Moline, (301) 504-6128, hmoline@asrr.arsusda.gov

ARS researchers have found that Navaho black- berries last 14 to 21 days, far exceeding the 3- to 4- day shelf life of other varieties. Farmer complaints about blackberries going soft soon after they're picked led University of Arkansas breeders to ask ARS to evaluate many varieties the university had released over the years. An ARS scientist discovered some exceptions that don't go soft quickly–notably Navaho, the first early thornless, erect-plant-type blackberry, released in 1988. Navaho stays firm 2 to 3 weeks, eclipsing even the latest breeding lines. In tests, Navaho berries were stored in coolers like those used by the industry to hold blackberries before transport to stores. A test shipment sent to the Netherlands arrived in the same condition as they were picked: firm, exceptionally sweet and consistently tasty. ARS scientists speculate that Navaho's extra firmness derives from its berry structure, cell wall structure or lower rates of enzymatic action. Blackberry acreage in the South has steadily expanded, and the new finding has further renewed growers' interest in marketing Navaho, especially to distant markets. The research shows that high-quality blackberries are now available for consumers.

South Central Agricultural Research Laboratory, Lane, OK Penelope Perkins-Veazie, (580) 889-7395,
pperkins@ag.gov

Last Updated: April 29, 1998
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