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Whiskey (and other spirits) Degradation and Oxidation

Hi. Does anyone have a resource or point of reference for what happens to barrel aged spirits after they are opened? I know that nothing BAD is actually going to happen to it, but I also know that there will be an evaporation of esters and alcohol alike. Most of the time, this doesn't matter much, but that bottle of Yamazaki 35, Maccallan M, or Hennessy Richard may not sell very quickly, and it damn well better taste like it was meant to when the consumer pays that kind of money. What is the time limit on this? If the bottle has been sitting on the shelf for three years because the owner is a rabid collector of status symbols, how much has the whiskey or brandy changed? 

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  • In my experience when running a high end spirits program I tend to focus on training (in order to move product) and less on wondering about the chemistry of how spirits evolve. If you're not already familiar with the science of fluid dynamics in relation to ethyl evaporation & temperature displacement then don't worry about it. If a product is on your back bar for more than 12 months then you need to review your training program. Dead Stock can kill you in the long run if you don't have the storage space; and if your staff isn't capable of making the sale then it will never move which profits you nothing. But if you want to get technical to keep up with the Hipsters (that don't know anything anyways) then here is what to look for.
    There is always a certain pressure exerted by the ethanol on the solution in the bottle (dependent on the type of enclosure used to seal the system) , called vapor pressure, which is dependent on a dynamically changing temperature environment. You can monitor the effect by adding a condenser to remove the ethanol vapor, thus creating a much more complex, dynamic system (do you really want to do this for every single bottle behind your bar?). The simplest way to determine the rate of evaporation would be to measure the amount of ethanol extracted at various time & Temperature intervals and plot these against a timetable. The rate would be the slope of the plotted line (which probably will not be constant, since as the amount of ethanol decreases from the original solution, it will slow the rate of collection.)...
    For me it all comes down to how you manage your program and understanding your guests, we've all had the owners that want grand products on a list just for the sake of having them. The best advice I can give is to treat your high end spirits, beer & Nihonshu just like wine. Minimize their exposure to light, temperature & oxygen. And train your staff to give them the tools needed to successfully sell. To make it fun go to Tales of the Cocktail, there you can find a myriad of resources & drinking buddies. Cheers!
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  • In my experience when running a high end spirits program I tend to focus on training (in order to move product) and less on wondering about the chemistry of how spirits evolve. If you're not already familiar with the science of fluid dynamics in relation to ethyl evaporation & temperature displacement then don't worry about it. If a product is on your back bar for more than 12 months then you need to review your training program. Dead Stock can kill you in the long run if you don't have the storage space; and if your staff isn't capable of making the sale then it will never move which profits you nothing. But if you want to get technical to keep up with the Hipsters (that don't know anything anyways) then here is what to look for.
    There is always a certain pressure exerted by the ethanol on the solution in the bottle (dependent on the type of enclosure used to seal the system) , called vapor pressure, which is dependent on a dynamically changing temperature environment. You can monitor the effect by adding a condenser to remove the ethanol vapor, thus creating a much more complex, dynamic system (do you really want to do this for every single bottle behind your bar?). The simplest way to determine the rate of evaporation would be to measure the amount of ethanol extracted at various time & Temperature intervals and plot these against a timetable. The rate would be the slope of the plotted line (which probably will not be constant, since as the amount of ethanol decreases from the original solution, it will slow the rate of collection.)...
    For me it all comes down to how you manage your program and understanding your guests, we've all had the owners that want grand products on a list just for the sake of having them. The best advice I can give is to treat your high end spirits, beer & Nihonshu just like wine. Minimize their exposure to light, temperature & oxygen. And train your staff to give them the tools needed to successfully sell. To make it fun go to Tales of the Cocktail, there you can find a myriad of resources & drinking buddies. Cheers!
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