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08/04/2014

The day I tasted 120 liqueurs and observed evidence of hydrogen bonding

by Isabel Graham-Yooll (Spirits Buyer)

While my colleagues plodded their way through Bordeaux En Primeur 2013, I attended to judging 120 liqueurs for the International Spirits Challenge.

While my colleagues began their days with pain au chocolat and ended with Chateau Margaux, my day began with a very strong coffee and ended with an explosion in a glass... but more of that later.  In the time between the coffee and the unrelated explosion my heroic companions and I nosed and tasted a rainbow of glorious liqueurs, each one with a tooth rotting 100gm sugar content.

Meanwhile in the next room the jolly gin judges enjoyed their day of 70 junipers.  In the room beyond them, in the hidden recesses of the 4th floor, the fearsome vodka panel tackled their 140 versions of neutral grain alcohol - the rumour is that these guys don’t spit.  We all remained in our pens, watched over by the adjudicators and separated by the officials like volatile football fans at a closely contested derby, presumably this was for our own safety.

The range of liqueurs was as broad in style as it was in quality.  The dramatic results of the contest will be announced later this year, in the mean time the pictures tell the secret inside story...

Adding water to my absinthe clearly illustrated the role of hydrogen bond formation and its effect on the heat of an ethyl alcohol and water solution.

The oxygen-hydrogen groups of ethanol formed hydrogen bonds with the water molecules. These bonded molecules were in a lower energy state than the separate molecules. The excess energy released by the bonding was converted into additional molecular vibrations and rotations, which basically meant it warmed up. Once I added enough water, and enough bonding took place, the energy released so much heat it began to steam up my glass!

At this point I went home and had indigestion.