From the fermented molasses, you want to get the “heart” or pure ethanol. The most volatile alcohol and thus the first distillate that comes out when heating the mash is the “heads.” This contains esters and aldehydes. The last alcohols to evaporate are the “tails.” The heart comes in between. But you want just the smallest touch of heads and tails since heads have notes of floral, banana, herbs, and the tails have notes of pears, apples, guava. It is much easier to capture the “heart” in a column still.