The Distilling Research Grant (distillingresearch.org) Advisory Committee recently funded research into “A Novel Real Time Quantitative Analytical Spectroscopy Technique for Analyzing All the Congeners Emerging from a Distillation Process” by Robin Felder, Ph.D.
If you don’t have a doctorate in chemistry, you may be glazing over, like you did in high school chemistry, and asking, “What do all of these words mean and how are they relevant to craft distilling?”.
We all know what congeners and distilling are. Novel is new, and real time quantitative means gathering data in the moment. So that gives us: a new way of measuring congeners in distillate.
But what is spectroscopy? Spectroscopy is a branch of science that measures light energy produced when a sample interacts with electromagnetic radiation. A spectrophotometer is a common piece of equipment in biotech manufacturing. A sample is placed in a cuvette (a small, clear, tube-like container), and specific frequencies of light are shined into the sample. The amount of light that passes through the sample is measured to provide data on the sample.
Current methods of analyzing the distillate coming off of a still use chromatography, which usually separates out the sample into components based on the size or charge of the molecules. But there are limitations into what it can reveal: It can’t tell the difference between molecules that are the same size or have the same charge. Furthermore, chromatography can’t identify a molecule that has never been measured before, which often occurs in products from natural sources (e.g., fruit, grains, herbs).
The article http://www.chromatographyonline.com/fourier-transform-molecular-rotational-resonance-spectroscopy-bridging-gap-between-spectroscopy-and is an introduction into Fast Fourier Molecular Rotation Spectroscopy (FFMRS) and how it performs both spectroscopy and chromatography, but may be rather difficult for the non-scientist to read.
In basic chemistry, there are mirror image molecules and chiral molecules. Mirror image and chiral molecules can have very different properties from each other and sometimes can be toxic, such as Penicillamine, an arthritis drug, which has a chiral version that is toxic. Modern chromatography cannot easily separate these.
FFMRS can determine exactly which volatile organic compounds (molecules, congeners) are coming out of a still. A sample is volatilized as in gas chromatography, but instead of running the gas through a column it is shot with microwave radiation by the FFMRS instrument. Each molecule in the sample yields a unique rotational resonance frequency, which identifies the compound. The strength of each signal is proportional to that molecule’s concentration.
Picture pulling on two springs that are made from different metals and attached to a wall and then letting them go: The unique way that each spring bounces around until it comes to rest is essentially its rotational resonance. Hundreds of different molecules can be analyzed at once in concentrations of parts per million to parts per billion. Molecules made up of the same atoms but with different chemical structures can be differentiated with this analysis. If the previously mentioned spring experiment were performed with identical springs except wound in opposite directions, they would bounce around differently.
These devices are new to the market and currently cost approximately $60,000. In the next few years as use expands and demand increases, expect this price to decrease. There is currently a company BrightSpec (brightspec.com, Charlottesville, VA) looking to expand use in the pharmaceutical industry, and the new technology shows great promise for distilled spirits production.
Robin Felder, Ph.D., has been chosen to receive the inaugural DRG grant to research practical applications of FFMRS for distilled spirits. Dr. Felder will use the $6,400 ADI grant to analyze the amount of the congener ethyl 2,4-decadienoate (EDDO) in pear brandy and determine which pear varietals will likely produce the most flavor in a finished spirit. FFMRS looks as if it can open the door for analyzing what happens at all processing steps and can help determine how distillers’ decisions from raw material selection through to proofing affect finished products.