Tony Salles, master distiller of El Tequileño tequila, was faced with a dilemma. His brand had recently achieved wider distribution outside of Mexico and in Canada, and some northern customers were complaining about seeing solids in their bottles.
He knew this was because the fatty acids that contain aroma and flavor components, called esters (natural components of agave), had solidified in the freezing temperatures. He didn’t know exactly what to do about it.
“We sell mainly to Mexico, where it’s hot, so in 60 years of production, we’ve never had this problem before,” Salles says.
When it comes to removing solids, some spirits producers choose a process called cold filtration, which cools the liquid to around freezing point (26 to 32 degrees Fahrenheit), then scrapes the solids from the top . However, Salles believed this process would change the profile of his tequila.
“It’s like putting chicken soup in the refrigerator overnight,” he says. “If you scrape the fat off the top of the broth and reheat it, it won’t taste the same.”
Tequila, like most other spirits, is usually filtered before bottling. Producers often use paper, cellulose (a more porous plant material), or activated carbon to remove any unwanted particles left behind from the production process. It can also improve the texture and create shine in the tequila. But filtration is rarely considered an essential step in tequila making.
“Filtration is a process that has been learned from generation to generation based on the technologies we had available at the time,” explains Salvador Rosales, Jr. by Tequila Cascahuín, who runs the distillery with his father, Salvador Rosales Sr. “We look to first remove any unwanted particles, usually by using paper, and then it comes down to the type of profile you are looking to create. “
Some methods are known to reduce alcohol burn or make tequila smoother to drink, such as activated charcoal, he says. But it can also take away some of the aromas and flavors, making the tequila simpler. For some consumers this is preferred.
The recent rise of cristalinos – aged tequilas that are filtered until they appear clear, like a blanco – has brought more attention to tequila filtration. Producers of these products often rely on activated carbon to remove color, knowing that many flavor and aroma components will also be lost. This creates a “milder” tequila.
If filtration is the determining step in the crystallinos manufacturing process, in other expressions it is considered the final touch. Except when your customers are worried about cloudiness.
An activated carbon filter at the El Tequileño distillery.
“Activated charcoal has been widely used in tequila to remove the ‘haze’ (or fatty acids),” explains Eduardo Espinosa de los Monteros of Filtration de Proceso, which has 15 years of experience in the filtration of high-value liquids.
He points out that there are grades of carbon, such as micropores and macropores. These have different “adsorption” capabilities, or concentration of molecules on the surface. Micropores help eliminate odors, while macropores eliminate stronger colors and strong flavors, says Espinosa de los Monteros, which is probably better for crystallino production. But any carbon filtration will change a tequila’s profile to some extent, depending on the concentration used and the amount of contact it has with the liquid, he notes.
That’s why Salles de Tequileño wasn’t considering carbon filtration for its regular line, even though it recently began producing a cristalino that uses carbon filtration to remove the color left by barrel aging.
He already uses paper, cellulose, polypropylene (a type of thermoplastic), and a very old ceramic filtration method that he learned from his father to ensure his tequila was clean and bright. So when it came to the issue of fatty acids, he thought more about education.
“Tequila is a natural product, with fats that contain flavor. It’s not the same as vodka, which is appreciated for its neutrality,” explains Salles.
But to respond to customer feedback, he conducted an experiment using cellulose to filter his “ordinary” (the liquid produced during the first distillation of the tequila making process.) The cellulose seller assured him that filtering at this point would eliminate the problem of solids forming in cold weather.
Some of the ordinario was filtered 100% by cellulose, others 75%, 50% and finally 25%. (A photo of the sample bottles is at the top of this story.) His team taste-tested all the samples against their normally produced blanco. The consensus came quickly: even at 25% filtered, the tequila did not have the same taste.
“We lost some complexity and flavor,” Salles says. Ultimately, they decided not to change their process.
Although Tequileño has decided not to filter its ordinario, a number of other producers choose this method to remove unwanted particles and prevent their finished product from being cloudy.
“We did a lot of trial and error,” says Jose Valdez, general manager and Tequilero maestro of Tequila Partida. “For us, charcoal filtering and cold filtering took away too much flavor.”
Instead, Partida uses paper and cellulose filters to clean its core line of tequilas and prevent cold haze. (They too have recently started producing cristalinos and use carbon filtering for these products.)
A common cellulose filtration device will involve several cellulose plates and pass liquid through them under pressure.
At Distilleria Cascahuín, they have avoided cold filtration on their main Cascahuín line in Mexico, even though they have a system on site.
“We use cellulose cartridges to gravity filter, without even using a pump, so it gently removes particles, but doesn’t change the profile of our tequila,” Rosales Jr. explains.
They use cold filtration for certain products intended for export, except when it comes to Cascahuín exported to Japan. Since the importer was already aware of esters and their solids-producing potential, he decided to put a sticker on his bottles, informing customers that these fatty acids are an integral part of the tequila manufacturing process.
At the Feliciano Vivanco distillery, NOM 1414, master distiller Sergio Cruz takes a similar approach. For finer tequilas, they use a gentle filtration method, allowing the liquid to pass through the cellulose by gravity. The objective is to eliminate unwanted particles that may come from tanks or barrels.
“These products generally don’t require a lot of filtering because we take care of every step of the process,” Cruz says.
However, when it comes to more economical products, it can pump tequila through plates of cellulose and activated carbon to clean up the rustic profile and mellow the flavors.
“It also depends on the product and the region (where it is sold),” says Cruz. “Here in Arandas people like tequila where the agave and alcohol are more present, so for them I don’t really need to do anything.”
This brings us back to Salles’ predicament. Will education around tequila production lead customers to view solids floating in their bottles as a sign of artisanal flavor? We’ll have to see.
Master Distiller Tony Salles explains the different filtration methods common in the tequila industry:
Our filtration notes
We had the chance to taste the filtered Tequileño samples from their experiment. Here are our notes:
– Comparing the 100% filtered sample with their normal product, the aroma and flavor are muted. There’s also a change in mouthfeel: this smooths it somewhat, but also flattens it. There aren’t the same bursts of flavor that you sometimes get with a tequila, especially on the finish.
– Even at 25% filtered, there is a slight flattening of aroma, but less effect on mouthfeel.
– The 50% filtered version is perhaps a happy medium if you are looking to reduce unwanted aromas/flavors, while still keeping some brightness in the profile. However, if it’s a well-made tequila, you may lose some complexity.
Common Questions (and Answers)
– Is it okay to put my tequila in the freezer?
Our opinion? No. This could cause the natural fatty acids in tequila to separate. These bring aromas and flavors to the tequila. We think chilling filtration is best left to the experts. However, it’s your tequila, so drink it how you like it!
– My tequila is cloudy/contains particles? Is it still good?
Usually, yes. If you shake the bottle while it is at room temperature, the particles or cloudiness should dissipate as the fatty acids are reabsorbed into the liquid. If there are blue particles floating at the top, this is usually copper from the still. When we notice this happening, we carefully pour it from the bottle and continue drinking what is left.
