A U.S. Department of Agriculture scientist is trying to figure out what makes avocados taste good.

The work of David Obenland, a researcher with the USDA Agricultural Research Service’s Parlier, Calif.-based San Joaquin Valley Agricultural Sciences Center, is highlighted in the March issue of ARS’s Agricultural Research magazine.

Obenland’s research focuses on aroma compounds. Hass avocados have at least 25 aroma compounds, and their role in avocados’ flavor has not been well-studied, he said.

The aroma compound pentanal, for instance, may be responsible for the nutty flavor of a ripe hass. Obenland and his fellow researchers hope to find a definitive link, if one exists.

If avocados’ aroma compounds can be pinpointed, they may serve as markers that breeders could use to grow new, better varieties. In addition, a knowledge of markers could help growers know when to pick avocados, and could help packers figure out how best to store and ripen fruit.

As part of his research, Obenland has done extensive taste-testing to identify the different aspects of an avocado’s flavor profile. More than 4,500 observations were gathered on hundreds of domestic and imported avocados.

In preliminary studies, Obenland and a group led by Mary Lu Arpaia, a researcher at the University of California-Riverside, tracked changes in the concentrations of aroma compounds.

They found that three chemicals — hexanal; (E)-2-hexenal; and 2,4-hexadienal — were likely responsible for a grassy flavor in avocados, and that taste-testers preferred fruit that had less of those chemicals.