This 1990 study in the Journal of Animal Science performed lots of surveys to find out if people could tell a flavor difference between corn-fed and grass-fed beef. The study made sure the fat content and texture of the two samples were similar, and then fed them to testers. The result? The grass-fed beef was found to have a "grassy" or "milky-oily" flavor, which the testers, accustomed (as most Americans are) to corn-fed beef, found less desirable than the "beefy" flavor of corn-fed meat. Diving deeper into the various studies, it seems that there are an array of flavor volatiles in the grass-fed meat that aren't present in the corn-fed; a chemical called phyt-2 ene, for example, was correlated with a grassy flavor. Other compounds, including diacetyl, 2- and 3-pentandione, octane, hexanal, 1-hexanol, and octanal were found to be associated with the "beefy" flavor in corn-fed beef. When the researchers injected the grass-fed beef with some of those "beefy" compounds, they found that the testers could no longer distinguish the difference between the grass-fed and corn-fed beef.