PEATED MALTS PRODUCTION
Peat is a historic record of the land, a result of vegetation progressively decomposing and becoming compressed. It is the main ingredient of peated malts.
A universal feature of peat is sphagnum moss, a plant characterized by small branches and leaves, which is able to retain vast amounts of water even after it stops living. This explains why the level of sphagnum moss determines the moisture level.
The composition of peat varies depending on the location and the vegetation it supports.
This element of terroir means that the range and concentration of phenolic compounds that peat conveys to the barley during the peating process depends on the source.
In peated malts world, there is an open debate about the intensity of peaty, smoky notes diminish during ageing or it only appears to do so, because the level of other flavours gained from the cask increases. Some blenders and distillers think the second. Others say there is a reduction due to the interior of the cask adsorbing phenolic compounds.
Another unsolved debate about peated malts is the influence of oxidation and evaporation on phenolics during the ageing process. Oxidation is thought to break down phenolic compounds, but what result this has is still being studied.
How phenolic character shows in a malt whisky is also influenced by the type of cask used for ageing. An English Whisky Company bottling of peated malt aged in a Bourbon barrel shows abundant vanilla aromas within smoke and fresh wood, accompanied by coals. The same batch of spirit aged in a Pedro Ximénez sherry cask has a gentle, drifting waft of smoke, with raisin aromas accompanied by a hint of leather, then chocolate moving on to vanilla.
A malt can also acquire phenolic characteristics during the ageing process.
Source: The Whisky Dictionary: an A-Z of Whisky, from history & heritage to-distilling & drinking
