What's in an Oil?

FAYETTEVILLE, Ark. — If you are what you eat, University of Arkansas researchers have found a way to reduce the time it takes to figure out what you’re eating, if it contains fat. The researchers have reduced the time it takes to characterize edible oils from several days to five minutes. This drastic reduction in time will help industrial food chemists and importers increase efficiency and reduce costs, which may one day lead to savings for consumers.

Jackson O. Lay Jr., director of the University of Arkansas Mass Spectrometry Facility; Rohana Liyanage of the UA Mass Spectrometry Facility; and Bill Durham, professor of chemistry, reported their findings in the journal Rapid Communications in Mass Spectrometry.

“It’s important to characterize fats so that people know what they’re eating,” Lay said.

Traditional methods of measuring the components of edible oils involve a process that breaks down the fats -- diglycerides and triglycerides into glycerol and free fatty acids — a process called saponification, which is also used to make soap. This process is time-consuming and transforms the original oil into a different product, one in which the diglycerides and triglycerides can’t be distinguished.

“For years, people assumed that it didn’t matter, but it turns out that it matters a great deal,” Lay said. The two types of fat are metabolized differently, and diglycerides may be beneficial to human health. So knowing the ratio of diglycerides to triglycerides may turn out to be of interest to nutrition researchers.

Lay and Durham wondered if it would be possible to develop a direct method for characterizing edible oils. They decided to try a type of mass spectrometry called matrix-assisted laser desorption/ionization mass spectrometry, or MALDI-MS. Using this technique, the researchers dissolve the oils in hexane, mix them with another liquid and then measure the spectra to determine the mass of the different components of the oil. They can sort out the fatty acids of different weights.

For this experiment, the researchers purchased soybean oil, sunflower oil, corn oil, canola oil, olive oil, peanut oil, hydrogenated vegetable oil, shortening, butter and lard. When they compared the results of MALDI-MS to other characterization methods, they found agreement within 4 percent of research literature values and within 7 percent of values on package labels, which could be due to rounding in nutritional labels.

This rapid method for characterization can lead to other findings, the researchers said.

“Our method, given its speed, lends itself to a large statistical analysis,” Durham said. Food scientists could look at seasonal variations in oils, or determine what happens when oil begins to decompose.

The Statewide Mass Spectrometry Facility has performed research on polymers, lubricants, plants, microorganisms and even caffeine, Lay said. He credits the institution, particularly Donald Bobbitt, the dean of the J. William Fulbright of Arts and Sciences, with helping to build an organizational structure that allows researchers to use the mass spectrometers in efficient and creative ways.