Heart

The heart denotes the middle fraction in a distillation process and is the distillate that is considered the desired starting point for whisky production and further maturation. In practice, the distillate is separated into three main fractions: heads (foreshots), the heart, and tails. The heart contains the balance of alcohols, esters and other compounds that contribute to the whisky's structure and character, without the sharp or undesirable notes often found in heads, or the coarse fullness from tails.

• Placement and significance: The heart is typically located between heads and tails in the distillation and serves as the primary source of raw distillate, which is subsequently aged and fine-tuned through maturation and blending. The exact boundary between the fractions varies with the distillation method, the raw materials and the distillery's practice.

• Determination of cut:

• Sensory assessment: Aroma and flavor in samples captured during the process are used to determine when the heart begins and when the tails begin. Sensory assessment is crucial, as the heart must have sufficient purity while also possessing complexity.
• Measurement of alcohol strength (ABV) and time: ABV levels change through the process; cutpoints are often set by a combination of ABV and sensory cues. For pot stills, cutpoints typically lie around 60-75% ABV at the start of the heart; tails begin when ABV falls and notes change.
• Technique and practice: Distillers use samples of the distillate and adjust heat and condensation conditions to ensure the heart continues until signs of tails become evident.

• Variation between still types:

  • Pot stills: The heart is often drawn from the middle portion, aiming to cut around 60-75% ABV at the start of the heart; tails begin when aromas and compounds change character.
  • Column/continuous distillation: The heart is part of a continuous fractionation, and cutpoints are determined more by sensory cues and time profile than by simple ABV values.

• Characteristics and flavor profile: The heart provides the whisky's structure and depth. It is expected to be cleaner and more balanced than heads and tails, with notes of fruit, flowers, vanilla and light spice. The middle fraction carries a harmonious blend of esters and alcohols, which yields a pleasant, persistent body that can withstand aging and further refinement without being diluted by unwanted components.

• Factors affecting the heart:

• Distillation equipment: Pot stills offer greater flexibility in cutpoints and often result in clearer differentiation between heads, heart and tails; column distillation plants produce more continuous fractions, where the heart comprises a broader middle portion.
• Raw materials and fermentation: Grain composition, yeast choice and fermentation time influence the compounds that reach the heart, and thus its aroma and flavor profile.

• Temperature and energy control: Temperature profiles and heat distribution in the distillation column or pot still affect how quickly heads and tails separate from the heart.

• Application in whisky production: The raw distillate in the heart often forms the basis for further maturation and blending. The choice of which parts of the heart are used affects the whisky's character before aging, and after aging, the handling of the heart becomes a crucial part of the final bottle profile.