Slices of wagyu rib meat.
Slices of wagyu rib meat. Schellack/CC BY 3.0

Wagyu beef is considered by many to be the paragon of meat. The beef from four breeds of Japanese cattle is famous for its beautifully marbled fat, soft texture, and sweet aroma, which some say is reminiscent of coconut or fruit. But what makes it smell that way? A recent study, published in the Journal of Agricultural and Food Chemistry, found that a cocktail of molecules is responsible, including one that recalls the scent of egg whites.

Scientists have tried to determine the chemical composition of the wagyu beef odor before, but their “sample preparation did not use the optimal cooking temperature,” write the study authors—which seems like a painful disservice to the notoriously expensive steaks. The authors, scientists at Ogawa and Company, a Japanese flavor and fragrance chemical firm, were meticulous in their preparation of three kinds of beef in the study—wagyu from Matsusuka, alongside grass-fed from Australia and a sirloin from the United States, for comparison. They used sous vide, which cooks the steaks in temperature-controlled water bath. The cooked meat was then blended and subjected to a solvent that helped separate out the volatile molecules responsible for the aroma.

Out of those slurries, the researchers found about 20 different odor-related molecules, including 10 compounds that hadn’t been associated with the smell of beef before. Eight of those are molecules that “have fatty, green, juicy odors,” write the authors. Another compound, which “had a unique egg-white note” that’s also found in chicken, is likely a big contributor to the wagyu bouquet. It is the relative proportions of these aromatic compounds that make the Japanese variety so distinctive. “The many kinds of potent odorants in each beef aroma are common,” the food scientists write, “however, the balance of their contributions is different from each other.”

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