The Essence of FILTRATION

By: Tracey L. Kelley

In the classic John Wayne film “The Quiet Man”, Irish lass Mary Kate Danaher asks the town’s local matchmaker, Michaeleen Óge Flynn, if he’d like a little water in his whiskey. “When I drink whiskey,” Flynn puffed out his chest, “I drink whiskey. When I drink water, I drink water.” Yet a wee drop or two of water to a dram of almost any finely-crafted spirit, especially whiskey, will enhance the flavor profile.

Rewinding now, from glass to finishing, finishing to production and raw ingredients awaiting the boiler or still—water flows through every stage. For the majority of distillers, its quality can’t be controlled at the absolute source. Water also has a tendency to, well, grow things. These spoiler organisms often adhere to other ingredients in the batch. Without proper filtration, they cause a host of problems through each stage of product development. 

  Beverage Master Magazine asked James “Jimmy” Fagen, East Coast sales manager for Craft Brew Water, Inc. what distillers need to remember about this essential ingredient.

“Rain, well and surface water is constantly changing throughout the year, and should be looked at by the ‘ranges’ of its make-up,” Fagen said. “These changes affect the look and taste of a distiller’s product and the maintenance of their equipment.” Craft Brew Water, based in Thousand Oaks, California, manufactures customized water filtration systems for distillers and brewers, as well as filtering sets and media.

Fagen suggested that since water consistency minimizes surprises in the final product, determine water quality at a baseline level. “For mineral content, measurement of Total Dissolved Solids (TDS) levels should always be the same when you start. This can be achieved with the use of Reverse Osmosis (RO) treatment, a blending valve—used for brandy—and real time TDS measurement.”

Filtering Differs By Source and Product

Adam Cox is the general manager and head distiller of Iowa Distilling Company in Cumming. During production, he said, some problems can be remedied. Others need proper filtration. “The high-temperature fermentation process can essentially cook off a lot of water impurities and chemicals,” Cox said. “But it’s more difficult to control water minerals or changes in minerals. Knowledge of this determines what type of filtering you need for both the front end and the finishing end.” The distillery’s corn-based product line includes Straight Bourbon, Zone Vodka, Steel Drum Rum and Madikwe, a natural cane spirit.

For every bourbon or whiskey enhanced by trickling water through limestone or a British gin shipped to Iceland for filtering through volcanic rock springs, different producers may have sand and other sediment leeching into their sources when they don’t want them. These are natural interferences. The man-made ones require more filtering diligence.

“City water suppliers, using federal water standards, will add chemicals,” said Fagen. “Producers can achieve chemical removal through carbon filtration systems. Granule-activated carbon will remove such chemicals. Make sure when you select carbon, don’t do it by price: do it by the quality as described by the manufacturer.”

Fagen cautioned that if your water supplier is using chloramines—chlorine and ammonia—for disinfectant, you’ll need catalytic carbon to remove this combination. Penn State Extension service describes catalytic carbon as a more concentrated form of activated carbon that works similarly to an oxidizing filer, absorbing chloramines, hydrogen sulfide, iron, and magnesium in greater quantities.

Carbon filtering is probably one of the most popular natural choices for distilleries. Jayson Barker in the manager of Mile Hi Distilling in Wheatridge, Colorado. The company offers an extensive selection of distillery equipment and supplies, as well as copper and stainless steel moonshine stills. Barker recommended porous activated carbon for a variety of spirits.

“Carbon filtering is similar to the way a carbon water filter works for drinking water: it removes impurities to make drinking water more desirable. Using a back purge steam system can re-activate carbon so it can be used over and over again,” he said. “When making some spirits like vodka, activated carbon filtering is used after the distillation process to create a high purity neutral spirit. Some distilleries also use a small amount of carbon filtering to help make non-neutral spirits more smooth.” Conversely, Barker said, too much carbon filtering in grain- or fruit-based spirits removes the flavor.

Generally, each spirt benefits from particular filtering methods. Here are a few often discussed:

  • Gin: the purity of the ethanol base is hotly contested depending on whether it should be filtered for absolute neutrality, or left with a bit of essence to marry to the botanicals.
  • Liqueurs: here’s when colloidal sediment removal is tricky, as the “goop” simply can’t pass through some filters. Some producers consider mechanical push filtration to be the best option.
  • Moonshine: activated carbon works well to remove toxins, organic materials, and odors. But, as Barker mentioned, too much filtration for this spirit also alters the profile.
  • Sake: after the rice starch converts to sugar, solids have to be removed. This mash isn’t filtered but actually pressed or squeezed through a mesh filter. Then, the liquid passes through a filtration process that includes a fine charcoal powder, which further removes impurities and enhances flavor and color.
  • Scotch whisky: an additional filtering method for removing haze in scotch below 46 percent ABV is chill filtration to stabilize fatty acids, esters and proteins. Isn’t it easier to raise the ABV and avoid chilling altogether so flavor won’t be compromised? Both approaches spark much debate.
  • Tequila: most producers agree that distillation alone can’t meet the impurity removal regulations for this spirit, so carbon filtering is a necessary step.
  • Vodka: as referenced, carbon filter heightens all aspects of this product, but different categories of this spirit are filtered at different speeds depending on the desired result.
  • Whiskey: some producers believe you can use one whiskey sample and create distinctly different profiles simply by altering the filter material, its density, the use or non-use of charcoal and other factors.

Regardless of product, Fagen said, nothing affects it more than the finishing process, or cutting. “Cutting refines the alcohol levels, look and taste of the product. This is where the rubber meets the road. Existing gravity-fed filtration systems limit the type of carbon used for a product and the number of times that product is filtered.”

Barker detailed the cutting process: “First, a producer collects the foreshots and heads and discards them. These first cuts have undesirable compounds that boil off at a lower temperature than alcohol.” He continued. “The next collection is the hearts—the premium spirit cut and the most desired part of the run. Then the tails, which brings over more fusel oils and undesirables. Some of the tails are what helps give spirits character, but too much can give off other flavors and make clear spirits cloudy.”

When Technology Can Help

The process of filtering spirits has come a long way from the days of silt, grass, and animal skins. But the quest to capture the most miniscule of particulate continues, and online forum talk often features distillers comparing microns—that elusive unit of measurement where smaller is better. For example, 50 microns is the width of a human hair. We can’t see anything with the naked eye below 40 microns. A filtering of 30 microns seems acceptable by most producers, but some often tell tales of 10 or less. Since bacteria is approximately two microns, it easy to understand why there’s such a fuss.

“Changes in design and the types of media that we can produce—from string to felt and from high-efficiency media to absolute membranes—means that the end use can capture more, hold more and experience a much more consistent and refined result,” said Robert J. LeConche Jr., president of Shelco Filters.  This nearly 50-year-old company in Middletown, Connecticut specializes in manufacturing filters and cartridges used in a multitude of industries.

Keep in mind that a filter’s micron rating isn’t the only factor to evaluate: be sure to also ask about its nominal or absolute rating, contaminant capacity and efficiency rating percentage. Then, it’s a matter of evaluating your processes and ultimate liquid to consider filter options such as:

  • Bag
  • Cartridge
  • Crossflow
  • Pre-coat, with additives such as diatomaceous earth, cellulose or perlite
  • Sheet or stacked disc cartridges
  • A combination of any of the above

Now, finishing methods are a completely different subject—some producers don’t always consider this stage filtering as much as refining. The rise in RO, which is what Iowa Distilling Company uses for its Zone Vodka, combined with precise filtering makes a difference. “I think many more distilleries are using this,” Cox said. “Depending on your goals for aromas and tastes, you might be changing out filters more often—which you should do anyway—but RO allows for better quality when modifying the finish.” Some distilleries also pass water from the RO system through a deionization (DI) system to improve purity and achieve a pH level of 7.0.

Fagen at Craft Brew Water believes that filtration has and is continuing to evolve the most in its efficient use of water. In turn, he said, this improves a producer’s productivity at acceptable cost levels. He listed many options. “RO system efficiency has greatly reduced the ‘concentrate’ water that contains removed mineral content. Cold RO membranes improve the RO process for cold water regions,” he said. “Anti-scalant systems add longevity to the RO membrane and equipment. UV light treatment kills bacteria very effectively. Programmable carbon filtration systems allow backwashing on your timetable without manual attendance. Scheduled, consistent backwashing minimizes water usage.”

Both Fagen and LeConche stress the importance of asking vendors for customized solutions. It’s hard to spitball capacity needs and specific spirit processes then match them with off-the-shelf machinery. For instance, if the output of a microdistillery averages 50,000 proof gallons a year, plate filter or lenticular filters systems using cartridges might be a cost-effective choice. Housings can be modified as well with expansion. Whereas a larger distillery might require the efficiencies found in filter sheet technology, which often includes sheets built to precise width specifications, and feature multiple grades, low extractable ions or even layered with activated carbon.

Also consider working together on new advances. Craft Brew Water is developing an automated end product filtration system using all types of carbon media, inter-changeable, with multiple filtration cycles and testing stations for quality control, Fagen said. “We’re in the proto-type development stage, and have a Patent Pending status. We anticipate the onsite testing process to begin within the next 30–45 days.”

Just as water plays a key role in each stage of creation, your filtering vendor can as well. “My advice is to make sure you pick a partner who has the experience to work with your system from start-to-finish with a defined end result in mind,” LeConche told Beverage Master Magazine. “Some people consider filtration products to be part of a parody industry, but nothing replaces thorough knowledge when setting up a system.”

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