In the interests of fresh-beer science, researchers at the University of California-Davis recently measured how quickly and under what conditions acetaldehyde forms.
The scientists, led by Takayuki Shibamoto, bought some beer from a brewery and measured its acetaldehyde level. They poured the beer into bottles, then sealed and stored the bottles at various temperatures.
Three months later, unlucky tasters sampled the warm, stale beer. The beer that had been stored at the highest temperatures -- more than 120 degrees Fahrenheit -- "was not subjected to rigorous sensory panel evaluation," the scientists noted. But even a cursory taste revealed that its flavor was definitely "off."
And that's not surprising because the beer contained 873 percent more acetaldehyde than it did when it was fresh, the scientists report in an article to appear in the Journal of Agricultural and Food Chemistry. Beer stored at lower temperatures had appropriately lower levels of acetaldehyde. The researchers also found that less acetaldehyde formed when they added GIV, a compound that is extracted from young green barley leaves. Using GIV as a preservative might make beer taste fresh longer -- helping out in countries where the beverage has to be transported or stored without refrigeration, the scientists wrote.
A new study suggests that sucking plants and animals dry is quite popular among nematodes.
In the latest issue of the journal Nature, researchers from eight institutions in the United States and Europe report on a family tree connecting 53 species of nematodes. To draw the tree, the scientists analyzed an equivalent gene from each species. The more closely related the genes, the closer the corresponding species were placed on the tree. The researchers noticed that animal parasitism has evolved at least four times and plant parasitism has evolved at least three times.
About 15,000 species of nematodes are known, ranging from microscopic to gigantic. The species Placentanema gigantissima, which parasitizes placentas of sperm whales, can grow to more than 25 feet long. Other nematodes are just over a millimeter in length.
Knowing how nematodes are related could help researchers combat the parasitic ones. Scientists could learn more about them by studying their nonparasitic relatives, which are usually easier to grow in the laboratory.
Carbon monoxide detectors might prevent more than half of all deaths from the odorless gas, a new study suggests.
Researchers from the Centers for Disease Control and Prevention sifted through records on poisoning victims in New Mexico between 1980 and 1995. Of the 136 deaths not related to fires, 80 people were in homes and 56 in vehicles. Most of the victims were awake when poisoned; however, tests showed that about 42 percent were legally drunk. Number of deaths tended to be higher in the winter, the result of improperly vented heaters or car exhaust systems.
Last week in the Journal of the American Medical Association, the CDC researchers estimated that detectors could have warned the victims who were not intoxicated about the gas.
Given the number of people with high blood-alcohol levels, the scientists said, public health campaigns should address the role of drinking in carbon monoxide deaths.
More than 2,000 people die each year in the United States of carbon monoxide poisoning.