Scientists Blast Ultrasound Waves to Age Booze at Hyperspeed

The world would be a chiller place if everyone could partake in a tumbler of beautifully aged booze. Unfortunately, time is money, and few can afford to wait the 12 or so years required for oak barrels to impart their caramel charm. But what if we didn’t have to wait that long? A team of Spanish scientists has figured out how to appease the cheap and impatient — and it involves blasting liquor with ultrasound waves.

In an article soon to be published in the journal Ultrasonics Chemistry, the researchers report that they’ve successfully aged alcohol two years in just three days using variations of their technique. And the resulting product — they focused on brandy, a liquor distilled from wine — is pretty damn good, according to the eight trained judges who taste-tested the eight samples the sped-up aging process produced.

“Obtaining, in three days, a spirit with characteristics near to two-years-aged brandies was something really unexpected for us,” Valme García, Ph.D., a study author, told Discover.

What García and colleagues really discovered was a way to speed up the process by which flavor is extracted from wood. When booze is aged in barrels the normal way, chemicals in the wood known as phenolic compounds leach their way into the liquid, imparting their distinctive flavors. This process takes a long time; being such a hard wood, oak is remarkably resistant to deterioration.

Delgado-Gonzalez et al./Ultrasonics Chemistry

But blasting the wood with ultrasound waves — the same high-frequency waves used to check on pregnancies — creates little bubbles in the hard wood, which release their compounds when they eventually collapse. In the study, the researchers pumped young, high-quality holanda — that’s the wine distillate used to make brandy — through a tube full of American oak chips, then they blasted the apparatus with ultrasound waves at a frequency of 40 watts per liter, a strength they’d determined in previous experiments. They fiddled with other variables, too — such as the temperature of the liquid, the amount of oak chips they used, the consistency of the ultrasound pulse, and the movement of the liquid — and ultimately produced eight different brandies.

The sample that received the best rating from the judges had flowed continuously throughout the process and was bombarded with continuous ultrasound pulses. The liquor’s movement, combined with the ultrasound, they write, had a “synergistic effect” that resulted in 33.94 percent of the wood’s phenolic compounds being extracted. In previous experiments, they’d found that 80 percent of the total phenolic compounds that had been extracted over the course of a week had been leached in the first three days, so they conclude that “three days enough to obtain a reasonably aged product”.

In their article, they modestly report that their accelerated process allows them to “get spirits with characteristics of aged spirits by traditional methods in only three days.”

Their idea has the potential to drastically change the liquor industry — as long as its notorious snobbery doesn’t prevent them from adopting the new technology. In Europe, at least, the booze the researchers produced from holanda can’t legally be called brandy — that requires that the booze actually be aged in oak barrels — but whether blasting the barrels themselves with ultrasound will be considered cheating in the future remains to be seen.

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