Wine and Spirits Alchemy Accelerated Maturation
Rural Alchemy-4 Hybrid Filtration
How We Use UV, Barley Straw and Perlite to Improve Spirits
We use an in-house-designed and built finishing system that combines controlled ultraviolet light, certified-organic barley straw and beverage-grade perlite. Together, these stages reduce haze and suspended material and soften certain undesirable sensory characteristics while preserving the spirit's intended aroma, flavor and character.
Introduction
There are several ways to filter distilled spirits to remove haze and reduce undesirable tastes and aromas. Each method has advantages, disadvantages and, if used too aggressively, the potential to remove some of the character that makes a spirit distinctive.
We wanted something different: a gentle finishing process that would polish the spirit without polishing away the qualities we worked so hard to create. After years of experimentation, we developed a hybrid system combining ideas drawn from water treatment with perlite depth filtration, a method long used in commercial beverage production.
The result is an exceptionally clean, polished spirit that retains the flavor, bouquet and individuality created during distillation and maturation.
Hybrid Bioactive/Conventional Filtration
Our system was inspired in part by biofiltration, a pollution-control technique in which living material and microorganisms capture or break down pollutants. Our process is not a conventional biofilter, however. We have adapted some of its materials and principles to create what we call bioactive filtration, then combined that stage with a conventional vertical perlite-filter column.
The upper stage contains a lightly compressed bed of certified-organic barley straw resting above a cleaned and sanitized coarse sand-and-gravel support layer. The straw is exposed to a carefully controlled dose of C-band ultraviolet light, or UV-C. We believe this promotes useful photochemical reactions at the surface of the straw, although we have not yet identified every reaction involved.
The lower stage is a vertical depth-filtration column containing replaceable cellulose support disks and beverage-grade perlite. Perlite is an extremely light, porous mineral used as a filter aid. Its intricate microscopic structure creates a deep, winding path that captures extremely fine suspended material that might otherwise contribute to haze or an unpolished finish.
We use certified-organic barley straw to minimize the possibility of introducing residues from conventional agricultural chemicals. All materials that contact the spirit are cleaned, sanitized or replaced for each batch, as appropriate.
Why Does This Work
We need to be completely honest here: we do not fully know.
The process began as an experiment more than a decade ago, when we were looking for alternative markets for our farm's barley straw and cattail roots. Our first investigations involved small-pond clarification and contaminated surface-water remediation. Later, we increased and controlled the ultraviolet exposure to see whether it would improve the process.
We then passed inexpensive commercial distilled spirits through the experimental filter. In informal side-by-side tastings, the treated spirits tasted noticeably cleaner and smoother than the untreated samples. That did not tell us precisely what chemistry was taking place, but it did tell us that the process deserved further investigation.
When we later developed our accelerated maturation system - the maturator - we retained the barley-straw and UV stage and added a conventional perlite depth-filter column. The complete system now combines several possible effects: photochemical activity at the straw's surface, adsorption or retention within the straw, and mechanical depth filtration through sand, cellulose and perlite.
We may not yet have names for every reaction occurring inside the filter, but we can evaluate the result in the glass. Used carefully, the process clarifies and polishes the spirit without stripping away the aroma, flavor and character we want to preserve. That is exactly what we designed it to do.