Understanding Heads, Hearts, and Tails in Whisky Distillation
Distilling whisky is a intricate process that involves the separation of alcohol from water, and the different parts of the distillation process are often referred to by the terms heads, hearts, and tails. These terms often lead to confusion and misinformation. A detailed understanding of these fractions is crucial for producing high-quality whisky. This article delves into the definitions, collection methods, and significance of these whisky distillation components.
Introduction to Heads, Hearts, and Tails
Terms such as heads, hearts, and tails are particularly relevant to pot or batch distillation methods, which are commonly used in Scotland. The process of distilling whisky involves multiple stages to achieve the desired purity and character of the final product. In this article, we will explore how these fractions are collected and their importance in the distillation process.
The Collection of Heads, Hearts, and Tails
The first distillation batch involves the collection of all heads, hearts, and tails until nearly all ethanol is removed from the system. The second distillation, where the heads, hearts, and tails are collected, is crucial for the separation of the desirable spirit from the undesirable components.
Heads, also known as foreshots, are the initial runnings from the second pot distillation. These fractions are collected until they fail the demister test. The demister test involves mixing a sample with water to check if the solution ‘louches’ or becomes milky, indicating a high concentration of fusel oils. Fusel oils in the heads come from the previous batch and not the current one. They are often discarded because of their high concentration of impurities and unpleasant taste.
The Heart of the Distillation
The hearts of the distillation are the primary fraction collected during the second distillation. For Scotch whisky, this fraction is collected from the moment the demister test succeeds until the alcoholic strength of the distillate decreases to around barrel ~67V (or 63.5-66.5% ABV). This collected fraction is considered the premium part of the distillation, providing the finest and most elegant flavors.
Collecting the Tails
The tails, also known as the feints, are the lower alcohol runnings collected after the hearts. In Scottish practices, the distillation continues until around 98% of all ethanol is collected. These fractions are added to the next batch as they still contain significant amounts of ethanol.
Misconceptions about Heads and Tails
A common misconception is that the heads contain some hideous chemical residue from previous distillation batches. In reality, while the heads do contain some fusel oils from the previous batch, they primarily contain dilute ethanol and other volatile compounds. Methanol, on the other hand, does not typically appear in the heads of grain-based washes. It is mainly found in washes made from fruit, which come from the methylated tips of branched fruit pectin.
Scientific Insight
Several scientific papers have demonstrated that methanol is not concentrated in the heads but is distributed throughout the middle-running fractions (hearts). This is due to the lower boiling point of methanol and its lower activity coefficient, which prevents it from separating from water as readily as ethanol. Methanol is well known to be more active in dilute solutions, which further explains its distribution in the hearts and tails of the distillation process.
Continuous Distillation Process
Large and mid-scale distilleries often use continuous stills, where all light-key products, including the heads, hearts, and tails, are collected and distilled continuously. In these setups, the fusels appear in a fractionating column around the plate where the vapor is condensed to measure around 50-60V (~0.27 mol fraction ethanol). This indicates that while fusels are present in the heads, they are not the dominant component.
Conclusion
Understanding the collection and processing of heads, hearts, and tails in the distillation of whisky is crucial for every distillery. The hearts are the most valuable fractions, providing the essence of the whisky, while the tails can still contribute to the overall character when used judiciously. By debunking common myths and understanding the proper collection methods and scientific principles, distillers can produce high-quality, consistent, and flavorful whiskies.