Article No.10. Oxidisation – The Good & The Bad

The thing I find most fascinating about whisky is the ambiguity around the factors during the production phase that influence the aromas and flavours that define the liquid that is bottled.  I always enjoy smelling a freshly opened bottle of whisky.  It is at that point you get to experience the aromas of the liquid as it was when bottled at the distillery.

The second most fascinating thing I find about whisky is what happens to that liquid once the bottle has been opened.  The process of oxidisation begins, where air replaces the liquid that has been poured.  I am not going to pretend I understand the chemical reaction that goes on here nor plagiarise from someone else, so I will describe my experience of how oxidisation has had a positive and negative effect on two whiskies that I am very fond off.


Glenmorangie 10 Year Old Single Malt – 40%

Glenmorangie can be described as a light/delicate single malt.  It is said that this is due to the height of this stills which are one of the highest, meaning that only the lightest alcohol vapours make it to the top and are collected for maturation.

When you open the bottle, you will find floral and citrus notes with a hint of vanilla and some spice.  The mouthfeel is soft and gentle, and the finish is subtle.  Overall it is an easy whisky to get into, some may say that it is bland or not complex and others (like me) will say that it is refined and complex.

A bottle of Glenmorangie 10 never last more than a month or 2 on my shelf, however there was one instance where I bottle remained on my shelf for up to 6 months due to the number of other bottles I was going through. At the 6th month there was about 15cl left and I had not had a dram from it in the previous month.

My final few drams of this were not pleasant (I would never spill it down the sink).  This did not taste like the Glenmorangie 10 I know and love.  It was acidic, sour and carried a metallic note.  All the freshness of the citrus and floral notes was gone.  I put this down to the effect of oxygen as nothing else had change with the liquid.


Green Spot Single Pot Still Irish Whiskey – 40%

Green Spot is another one of my favourites, but it didn’t start of like that.  When I first opened the bottle, I could not get past the metallic note and I found it too concentrated, even with adding water and giving it time, I still could not find the lush fruity flavours you would typically find with pot still whiskies.  I found it quite frustrating because all my research suggested that I would enjoy it.  I rated this whisky around the 2.25 mark I think.

If I am not so fond of a whiskey, then it tends to stay sitting on my shelf for a good few months longer than other whiskies I am enjoying.  This was a blessing in disguise.  After 3 months and with about 3 quarters of the bottle left, I decided to revisit it.  To my amazement this tasted like a different whiskey to the one I tasted 3 months ago.  The astringent metallic note had softened, and I could smell the apples and fresh fruit.  The bottle did not last much longer.  I think I ended up rating this a 4+.

These two experiences have led to me be more conscious of how long I keep bottles open on my shelf and to be patient if I am not liking a whisky.  Whenever you pour a dram it is normally good practice to let it breath if you are struggling to pick up flavours.  I think this is also true for bottles.  Give it time if you are unsure, pour a dram regularly and see how it develops.  You may find that some bottles have a sweet spot.  For me, the sweet spot for Glenmorangie 10 is between 1-2 months and for Green Spot it is from 3 months plus.  However, there is one rule I apply to any bottle that only has a 5th of the liquid remaining, and that is to finish it off.