Author: Brad J Berron, PhD Publish Time: 2024-08-27 Origin: https://distillingresearch.org/
Castle and Key Distillery
Brad J Berron, PhD (Co-Investigator)
Current Occupation / Title:
Jon Brown – Quality Manager at Castle and Key Distillery
Dr. Brad J. Berron – Director of Research at the University of Kentucky’s Beam Institute for Kentucky Spirits; Associate Professor of Chemical Engineering at the University of Kentucky
Please provide how your background experience will provide the foundation for your research.
Jon Brown has been focused on the analysis of alcoholic beverages for over a decade. Under his guidance, Castle and Key Distillery has been monitoring EC levels and distillery operating parameters for over 700 production batches. This existing data set enabled a preliminary analysis of the biggest drivers for product EC levels, focused our analysis, and highlighted the need for further understanding of how craft scale distilleries can cost-effectively monitor and regulate EC levels.
Dr. Berron has taught several engineering courses at the University of Kentucky on the theory and design of distillation-based unit operations. He also designed and taught the University’s first course on Bourbon Production Engineering. Dr. Berron’s research lab designs and executes research studies for regional distilleries. His team recently presented a distillery-view report on the formation and elimination of EC in a bourbon production facility based on exhaustive literature review and interviews with distillers from Beam-Suntory, Buffalo Trace, Wild Turkey, Wilderness Trail, and Castle and Key Distilleries [1]. The presented work extrapolates from literature on other distilled spirits and incorporates reaction rates and volatility data to track the ideal path for EC and its precursors to exit a continuous distillation system.
Abstract
American craft distillers are increasingly producing for markets which regulate the content of ethyl carbamate (EC) through international sales or contract distilling. Craft distillers often leverage local raw materials in their signature products, and these local grains have dramatically elevated levels of EC precursors. The EC literature places little emphasis on American whiskeys, and there is a complete lack of literature on EC levels in bourbons and ryes produced on craft scale, continuous stills. Based on findings from existing literature for EC levels in other spirits at large commercial scales, this team proposes to quantify the effect of methods to manage EC levels in craft scale American whiskeys. This research team has done a preliminary analysis of existing data from Castle and Key Distillery to develop general trends that are in line with the findings found in other distilled spirits. The resources provided by this research grant would allow the collection of additional process data, a detailed statistical analysis to determine how strongly these parameters alter product EC levels, and a process analysis of these effects. These analyses will enable the craft distiller to confidently meet challenging EC targets in craft products that use local, EC precursor-rich malted barleys.
Background
Ethyl carbamate (EC) is a potential carcinogen that is regulated in many global markets. EC originates from glycosidic nitrile content in the grains used for distilling. While some malts provide lower EC levels in the final product [2-4], many craft distillers prefer the broader range of unique flavors available from other grain sources. Distillery operating parameters regulate EC levels through 1) controlling the rate of EC formation, 2) removing EC through nonvolatile streams, and 3) potentially removing volatile precursors through incomplete condensation. The major precursor compounds and steps are involved in the formation of EC are glycosidic nitrile -> isobutyraldehyde cyanohydrin -> hydrogen cyanide -> EC [2, 5].
Rapid conversion of hydrogen cyanide to EC drives the loss of the non-volatile EC through waste streams, while slow conversion allows hydrogen cyanide to reach the barrel where it slowly converts to EC [6]. The conversion of hydrogen cyanide to EC is catalyzed by copper ions, and distilleries rely on routine cleaning of abundant copper surfaces to accelerate catalysis [7]. Alternatively, the hydrogen cyanide has the potential to escape from the low wines condenser under common operating conditions.
While many of these phenomena are known, the quantitative impact of distillery operations on these potential interventions is poorly understood and not described in any scientific literature. There is little targeted guidance available for a craft distiller to decrease EC levels for an American whiskey product. The following research plan will determine how EC levels are controlled by specific changes in distillery operating conditions.
Materials and Methods
Month 1-8. The production team will identify up to 50 upcoming batches that will have the same mash bill and yeast to control for the following parameters.
Beta glucosidase levels in the yeast. Determined by Lallemand for each lot. Only data from batches with levels within 10% of the mean will be used for analysis.
Mash bill. Only mash bills consistent within 1% will be selected for this study. • Glycosidic nitrile levels in each mash bill component. The University of Kentucky will measure levels according to established assays in the literature [11]. Only data from batches with levels within 10% of the mean will be used for analysis.
We will systematically vary and record the following parameters during production:
Number of batches since caustic cleaning
Number of batches since citric cleaning
Feed tray location
High wines proof
Low wines condenser temperature setpoint
We will also record the EC level for each batch. Distillate samples will be aged in vials for 30 days for complete conversion of hydrogen cyanide to EC [10] before being mailed for EC testing at ETS Laboratories.
Month 8-12. Castle & Key and University of Kentucky teams will relate findings to practical guidance on distillery operation for low product EC. This analysis will include potential congener impacts of each operational change. We will also discuss how these findings qualitatively inform distilling approaches for EC management in other craft spirits, including malt whiskey and fruit brandies. These results would be compiled into an article in the Process section of DISTILLER magazine or a forthcoming ADI scientific journal.
