Chemistry of the Bar: Amaretto 101
At last week’s American Chemical Society meeting in New Orleans, a group of chemists came together to discuss the latest and greatest in alcohol. No, this wasn’t on Bourbon Street. And karaoke, to-go cups, and beaded necklaces weren’t involved (as far as I know).
This week’s issue of Chemical & Engineering News features a column I wrote about one of the session’s presentations. Neil C. Da Costa, a researcher at International Flavors & Fragrances, in New Jersey, entertained the audience with tales of the hurricane, that rum-based drink the Big Easy is famous for. I featured Da Costa’s studies of the hurricane because of the soft spot I have for the cocktail: The first time I drank one was during my undergraduate years at, you guessed it, my first national ACS meeting.
But I gave short shrift to other “Chemistry of the Bar” presentations. One particularly interesting talk was given by Jerry Zweigenbaum, a researcher at Agilent Technologies, in Delaware. Along with Alyson E. Mitchell and coworkers at the University of California, Davis, Zweigenbaum investigated the ingredients of the after-dinner liquor amaretto.
If you’re like me, you might have thought that because amaretto smells like almonds, it’s made from them. Zweigenbaum says that’s not necessarily the case.
According to legend, amaretto was first made in 1525 by soaking apricot kernels in alcohol. You can see the tale, conveniently located on the website of amaretto maker Disaronno, here. Apparently, one of Leonardo Da Vinci’s star pupils was asked to paint a fresco of the Madonna in the Italian city Saronno. His model was a local innkeeper who showed her gratitude by gifting the fellow a drink made from the infamous kernels.
Today, Disaronno says its amaretto contains “herbs and fruits soaked in apricot kernel oil.”
But the problem with alcohols like amaretto, Zweigenbaum says, is they are regulated by the Bureau of Alcohol, Tobacco, Firearms & Explosives here in the U.S., rather than by FDA. That means companies don’t have to list the beverages’ ingredients or nutritional content.
So what exactly Disaronno and other amaretto companies are putting in their wares remains a mystery. Zweigenbaum decided to find out.
The Agilent researcher purchased seven different brands of amaretto (he won’t divulge which ones) and tested them with various analytical techniques—headspace gas chromatography/mass spectrometry (GC/MS) and quadrupole time-of-flight liquid chromatography (Q-TOF LC), to name a few.
One volatile compound stood out in all seven amaretto brands: benzaldehyde. This is the chemical that gives amaretto its sweet, yet bitter, almond smell. “Amaro,” after all, is Italian for “bitter.”
But what’s benzaldehyde doing in amaretto? Zweigenbaum says that amygdalin, a glycoside found in apricot pits degrades to form benzaldehyde and the poisonous hydrogen cyanide. “So you don’t want too much of that in your drink,” he adds.
All the brands Zweigenbaum tested had low levels of benzaldehyde in them, he told me. One of the least expensive of the seven, which costs about 32 cents per shot (45 mL), had 10 times as much benzaldehyde as the others, though. It was “not pleasant when revisited with my nose,” Zweigenbaum says. Four of the brands contained no amygdalin at all, two of them had moderate amounts, and the most expensive amaretto (almost $1.50 per shot) held a large amount of the glycoside—so much it was at the detection limit of the instrument.
“You can’t conclude anything from these results, necessarily,” Zweigenbaum says. But they seem to suggest that a person could make amaretto by simply adding benzaldehyde to alcohol and sugar, he adds.
Zweigenbaum also notes that the most expensive brands of amaretto contain high levels of sucrose. “That makes sense because sugar is expensive.”
When looking at the nonvolatile compounds in the various amarettos he studied, Zweigenbaum found peaks for a potential 1,800 different compounds. “I was surprised to see so many,” he says. “But according to amaretto recipes online, the drinks include various spices.” Because spices are some of the most complex ingredients used in foods (in terms of chemical compounds contained within), it makes sense that the drinks produced so many peaks.
But again, the Agilent scientist points out, it’s not hard to imagine that companies would need to soak neither apricot pit nor almond in brandy or vodka to produce the sweet-smelling after-dinner drink. His data can’t tell one way or the other, he says, but “let’s say you took some brown sugar, spices, alcohol, and benzaldehyde,” he says. Voilà! Amaretto. No Madonna-esque innkeeper required.
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