For many of you, this will be a blinding glimpse of the obvious, but I see so many dumb approaches to cooling cocktails being pushed that I had to try to clear a few things up.
First, a bit of physics. Ice cubes cool your drink in two ways. First and perhaps most obviously, the ice is colder than your drink. Put any object that is 32 degrees in a liquid that is 72 degrees and the warmer liquid will transfer heat to the cooler object. The object you dropped in will warm and the liquid will cool and their temperatures will tend to equilibrate. The exact amount that the liquid will cool depends on their relative masses, the heat carrying capacity of each material, and the difference in their temperatures.
However, for all but the most unusual substances, this cooling effect will be minor in comparison with the second effect, the phase change of the ice. Phase changes in water consume and liberate a lot of heat. I probably could look up the exact amounts, but the heat absorbed by water going from 32 degree ice to 33 degree water is way more than the heat absorbed going from that now 33 degree water to room temperature.
Your drink needs to be constantly chilled, even if it starts cold, because most glasses are not very good insulators. Pick up the glass -- is the glass cold from the drink? If so, this means the glass is a bad insulator. If it were a good insulator, the glass would be room temperature on the outside even if the drink were cold. The glass will absorb some heat from the air, but air is not really a great conductor of heat unless it is moving. But when you hold the glass in your hand, you are making a really good contact between your drink and an organic body that is essentially circulating near-100 degree fluid around it. Your body is pumping heat into your cocktail.
Given this, let's analyze two common approaches to supposedly cooling cocktails without excessive dilution:
- Cold rocks. You put these things in the freezer and put them in your drink to keep it cold. Well, this certainly will not dilute the drink, but it also will not keep it very cold for long. Remember, the equilibration of temperatures between the drink and the object in it is not the main source of heat absorption, it is the phase change and the rocks are not going to change phase in your drink. Perhaps if you cooled the rocks in liquid nitrogen? I don't know.
- Large round ice balls. There is nothing that is more attractive in my cocktail than a perfect round ice ball. A restaurant here in town called the Gladly has a way of making these beautiful round flaw-free ice balls that look like they are Steuben glass. The theory is that with a smaller surface to volume ratio, the ice ball will melt slower. Which is probably true, but all this means is that the heat transfer is slower and the cooling is less. But again, the physics should be roughly the same -- it is going to cool mostly in proportion to how much it melts. If it melts less, it cools less. I have a sneaking suspicion that bars have bought into this ice ball thing to mask tiny cocktails -- I have been to several bars which have come up with ice balls or cylinders that are maybe 1 mm smaller in diameter than the glass so that a large glass holds about an ounce of cocktail.
I will not claim to be an expert but I like my bourbon drinks cold and have adopted this strategy -- perhaps you have others.
- Keep the bottles chilled. I keep Vodka in the freezer and bourbon and a few key mixers in the refrigerator. It is much easier to keep something cool than to cool it the first time, and this is a good dilution-free approach to the initial cooling. I don't know if this sort of storage is problematic for the liquor -- I have never found any issues.
- Keep your drinking glass in the freezer. Again, it will warm in your hand but an initially warm glass is going to pump heat into whatever you pour into it.
- Use a special glass. I have gone through two generations on this. My first generation was to use a double wall glass with an air gap. This works well and you can find many choices on Amazon. Then my wife found some small glasses at Tuesday Morning that were double wall but have water in the gap. You put them in the freezer and not only does the glass get cold but the water in the middle freezes. Now I can get some phase change cooling in my cocktail without dilution. You have to get used to holding a really cold glass but in Phoenix we have no complaints about such things.
Things I don't know but might work: I can imagine you could design encapsulated ice cubes, such as water in a glass sphere. Don't know if anyone makes these. There are similar products with gel in them that freezes, and double wall glasses with gel. I do not know if the phase change in the gel is better or worse for heat absorption than phase change of water. I have never found those cold packs made of gel as satisfactory as an ice pack, but that may be just a function of size. Anyone know?
Update: I believe this is what I have, though since we bought them at Tuesday Morning their provenance is hard to trace. They are small, but if you are sipping straight bourbon or scotch this is way more than enough.
Postscript: I was drinking old Fashions for a while but switched to a straight mix of Bourbon and Cointreau. Apparently there is no name for this cocktail that I can find, though its a bit like a Bourbon Sidecar without the lemon juice. For all your cocktails, I would seriously consider getting a jar of these, they are amazing. The Luxardo cherries are nothing like the crappy bright red maraschino cherries you see sold in grocery stores.
