Whisky is a complex subject with rich & diverse flavors that makes one inquisitive.
About 200 flavour compounds have been identified in a malt whisky. The level of various flavor compounds is measured in terms of parts per million(ppm), with 1 ppm equivalent to one milligram in a litre of malt whisky. However, flavor compounds are also measured in terms of parts per billion and parts per trillion, with even this level able to have an influence.
The first phase of flavour creation is producing a new-make spirit, with fermentation & distillation as the key stages. The flavour profile of the new-make spirit accounts for 40% of the flavour of the final product.
While ageing, the spirit gains flavours from cask while also developing through evaporation & oxidation. Oxygen is a crucial element that can instigate various reactions which promotes greater fragrance, fruitiness & complexity. Evaporation from the cask accounts for 2% of the volume of liquid annually and the decreasing volume of spirit sees a certain concentration of flavours. Evaporation & Oxidation also help lower the level of sulphur compounds, formed during fermentation which include vegetal, meaty, rubbery notes. Lowering it, enables lighter notes such as vanilla, fruitiness to show more distinctly. Vanilla is a key flavour with small amounts evident in the new-make spirit but it interacts with other flavors leading them to change. Fruit notes are provided by esters which are created during fermentation.
A dram of whisky is a platform which shows the nuanced flavors of the malt that has gone through the stages of fermentation, distillation and maturation, creating flavours, some in minute & others in considerable levels, leaving a huge sensory impact.