Roemah Minoem

The Science of Fat-Washing

“I was wondering what actually happens you fat wash spirits. Is it the same as a regular old infusion? Instructions always claim that once you chill, skim, and strain, you aren't left with any fat in the mix, but does some of it dissolve into the alcohol? It definitely feels like the texture changes.”

There aren't a whole lot of scientific papers that research the fat-washing of cocktails. So, I took a page from Sam Mason and considered the techniques of perfumers. Let's say you wanted to extract the flavors from an orange peel. As you may know, orange peels are lined with sacs filled with aromatic oils. That's why you can flame an orange twist—the oils from the peel are flammable. But perfumers don't only use oils for their aromas. While many powerful aromatic compounds are fat-soluble, others are water soluble. Consider the extremely aromatic orange flower water, for example. Orange flower water is an example of a hydrosol—the water-soluble aromatic compounds left over after oil-soluble aromas have been removed. Add alcohol to the mix and things start to get interesting. Alcohol (or ethanol/ethyl alcohol) can dissolve both oil-soluble and water-soluble flavors. That's because the alcohol molecule has two distinct ends, one of which is polar (water-loving) and the other of which is non-polar (oil-loving).

In the above illustration, the polar side is to the right of the image and the non-polar side is to the left. Whereas water is considered a powerful polar solvent, with a dielectric constant (εr) of 80, alcohol is a less powerful, but still effective polar solvent, clocking in at a respectable εr of 24.55. Any molecule with εr greater than 15 can act as a polar solvent. The non-polar side of alcohol has no εr and acts instead as a non-polar solvent, which gives it the ability to latch on to oil-soluble flavor compounds.

What does all this mean for fat-washing? The original question asked whether fat-washing is different from traditional infusions. And the answer is: not really. Regardless of whether you use vanilla beans or sesame oil as the flavor-adding ingredient, alcohol will extract a portion of both the fat-soluble and water-soluble flavors in that ingredient. If you used a pure oil, like olive oil, the majority of the flavor compounds would be fat-soluble ones. If you used butter—which is not actually a pure fat, but rather an emulsion of water and oil—you would capture both oil-soluble and water-soluble flavor compounds.

And how does fat-washing change the texture of a spirit? Many sources say that by freezing a fat-washed spirit, it's possible to strip out 100% of the original fat. Frankly, that's probably not true. Freezing the spirit solidifies the fat and makes it easier to strain, but it's very unlikely you'd be able to strain out every bit of the fat. There probably wouldn't be enough fat left to affect calorie counts, but even a small amount of dissolved oils could affect mouthfeel.

GRAPES
Vitis vinifera
VITACEAE (GRAPE FAMILY)

Quick: name a fruit that is made into alcohol. What comes to mind first? Probably grapes. But belive it or not, the very existence of grapes is surprisingly unlikely. The fossil record shows that grapes were established in Asia, Europe, and the Americas fifty million years ago. But when the last ice age, the Pleistocene epoch, began about 2.5 million years ago, vast sheets of ice covered much of the grape’s range and nearly drove it to extinction. The vines that managed to pass the time in unfrozen corners of the world were the only ones left for early humans to encounter. It’s entirely possible that the grapes that flourished before the ice age were far more diverse and interesting than what we grow today.

To make the success of the grape even more improbable, those early vines would have yielded nothing like the abundant clusters of sweet, marble-sized fruit we know today. The grapevines that survived the ice age were dioecious, meaning that each plant was either male or female. The vines depended upon insect to transport their pollen, and if a female was too far away from a male, it simply wouldn’t happen. The fruit from these couplings was unpredictable as well. Grapevines, like apples, can produce offspring whose fruit will be quite unlike that of its parents. Some of those grapes would have been small, bitter, and full of unpalatable seeds.

So what happened to improve the grape’s prospects? A mutation that changed the plant’s sexual orientation. In dioecious plants, the females are female because a gene suppresses the formation of male anatomy and vice versa. But sometimes those genes go awry and nature creates a hermaphrodite. The vines that resulted from those mutation had both male and female anatomy on the same plant. Because the pollen didn’t have as far to travel, the vines produced more abundant fruit. The earliest agrarians might not have understood why certain vines were more prolific, but they would have selected them to grow in their settlements. That selection process began about eight thousand years ago, and from there, it was simply a matter of choosing the tastiest fruit and taking cuttings to get a genetic clone. Fortunately, pottery was also being invented around the same time, leading to the happy circumstance of crushed fruit stored in a container long enough for wild yeast to find it.

One more lucky break made wine making possible. A particular species of wild yeast that feeds on the exudates of oak tree bark managed to crawl into early wine vats around five thousand years ago and do particularly good job of fermentation. There would have been other yeasts living naturally on grape skins, but they would not have been nearly as well suited to the job. But somehow, oak yeast go into the mix.

How did this happen? Scientist have a few theories. It might be that grape vines occasionally climbed up an oak tree and picked up the yeast. It’s also possible that people gathered acorns and grapes at the same time, commingling the microorganisms on each, or that insects picked up the yeast on an oak tree and carried it to a grapevines because it was attracted to the rising sugar in the fruit. However it happened, that yeast species, Saccharomyces cerevisiae, found its way into wine somehow. Today it is an entirely domesticated creature, rarely found in the wild and widely bred into specialized strains that are used around the world to make bread rise and to ferment wine and beer.

NEGRONI

This turn-of-the-century import from Italy was purportedly created by Florentine count Camillo Negroni, who requested that gin be added to his Americano cocktail, and the result is this complex triangulation of gin, bitter Campari, and sweet vermouth. Traditionally served over ice to slightly dilute the intensity, some prefer adding a splash of club soda, but it is equally enjoyable shaken and served up. The classic recipe dictates equal parts gin, Campari, and sweet vermouth, with variations that include lighter versions closer to a Martini, which are more suitably stirred than shaken.