Words by: Simon Difford
The final stage of production is when the malt is given its own distinctive packaging and branding. The alcoholic strength of the malt is usually reduced with purified water from about 60% alc./vol. cask strength to a minimum of 40% alc./vol. bottling strength.
Few distilleries bottle on their own premises - most send whisky at cask strength to a bottling line some distance away, where it usually reduced with purified mains water. Many brands are quick to talk about the source of the water they use at the distillery but few disclose the fact that their bottles contain close to 20% municipal water.
Look out for 'cask strength' malts, which are bottled at the strength they leave the cask. These undiluted malts are said to retain more of the essential flavours and should be drunk with a splash of filtered or spring water (preferably Scottish). A chemical reaction takes place when a whisky is hydrated and some of the whisky's character is lost. Thus cask strength whiskies allow the consumer to experience the release of aroma caused by this reaction.
Another common practice at the bottling stage is to chill filter the whisky to remove flocculants, mainly wax and long chain fatty acids which are likely to 'flock' and cause what is known as a 'chill haze' when the whisky bottle becomes cold during shipping or storage. This is not an issue with cask strength whiskies and on the packaging of such whiskies it is common to see the term "non chill-filtered".
Some brand owners filter at 0°C through an extremely fine mesh (NA120) while others favour a less harsh filtration at around +4°C through wider mesh filters (NA45). Heavy filtration can strip out fatty acids from the whisky adversely affecting mouthfeel and perceived smoothness. Thus look out for malts that stipulate that they are not chill-filtered.
Once bottled, single malt Scotch whisky is exported to around 200 markets worldwide.