What is the impact of prematurely cutting off the 'hearts' during distillation on the perceived mouthfeel of the final product?

Prematurely cutting off the 'hearts' during distillation will result in a final product with a thinner and less complex mouthfeel. The 'hearts' cut is the middle fraction of the distillate, considered the most desirable part, containing ethanol and pleasant flavor compounds. By prematurely ending this cut, you are excluding heavier, higher-boiling-point compounds, which contribute to the spirit's body and mouthfeel. These compounds, although present in the later part of the hearts and the early tails, contribute to the viscosity and textural qualities of the spirit. The 'tails' contain heavier alcohols, fatty acids, and other less volatile compounds. Example: Compounds like glycerol and certain long-chain esters, found in the tails, contribute to a smoother, rounder mouthfeel. While the tails can contain undesirable flavors that need to be carefully managed, some of these compounds, when present in small amounts, add depth and richness to the mouthfeel. By prematurely cutting off the hearts, you are essentially stripping away these heavier, mouthfeel-enhancing compounds, leading to a spirit that feels lighter and potentially less satisfying on the palate. The resulting spirit might taste 'thin' or 'watery' because it lacks the textural complexity contributed by the later-running compounds. Therefore, a distiller needs to carefully balance the hearts cut to retain enough of these heavier compounds to achieve the desired mouthfeel without introducing undesirable flavors.