Tuesday, May 5, 2009

Root Beer Floats: A Quest for Perfection, Part II

In the previous post I dealt with two of the most significant variables in the creation of the perfect root beer float (RBF): the ice cream and the root beer. In this post I will be covering the remaining variables: the ratio of ice cream to root beer, the proper vessel and utensils, the process, and the elusive but essential ineffable elements that go into the perfect RBF experience.

3. The Ratio
Before dealing directly with the proper ratio of ice cream to root beer, let me address one fundamental issue. The perfect RBF has two ingredients: ice cream and root beer. If it has anything else in it, it ceases to be an RBF in my mind. If you want to put your own personal cocktailian spin on it and add a dash of Cointreau, a ribbon of lime zest, or a cube of sugar soaked in absinthe, go right ahead — just call it something else, and for god's sake don't serve it to anyone without ample warning.


The perfect RBF is an excellent example of what is known as the Goldilocks Principle. Remember the story of the thieving little girl that broke into an innocent bear family's house, stole their food, and slept in their beds, all the while complaining that their food was either too hot or too cold, their beds too soft or too hard, until she found one that was just right? The Goldilocks Principle applies to scenarios in which there is a range of acceptable states between two extremes. As with the purloined bear food, there is a "just right" or Goldilocks equilibrium state between two extremes of the ice cream to root beer ratio in RBFs.

So it's true that there is a range of ratios in which you'll be safe - a little bit one way or another and you'll survive. However, there is a point of maximal perfection which can be achieved by having 1 unit of ice cream for every 1.6 units of root beer by volume. The middle image above shows a mug that is just over half full of ice cream, but keep in mind that the root beer should be added in stages (see below under "The Process"). By odd coincidence, or perhaps some odd sort of divine providence, this ratio happens to be the golden ratio, often held to be the most aesthetically pleasing ratio in the arts.

Leonardo Da Vinci's "Vitruvian Man," from the Latin vitrus, meaning "glass-bearing man" - a classic artistic example of the golden ratio

4. The Vessel and Utensils
The proper vessel for an RBF is a mug, specifically a frosty glass mug. As a backup you can use a fountain glass (i.e. a shake glass), or in times of desperation a pint glass.


The proper vessel frosted from a brief rest in the freezer. A&W logo and Snoopy are not required, but certainly don't hurt.

Temperature is extremely important for RBFs. Using anything less that fully chilled root beer is a risky proposition; warm root beer will result in quickly melting ice cream and a milky mess. Chilling the mug is a key step in keeping the RBF cold and promoting the formation of “frozen edges”. What are frozen edges you ask? When conditions are just right (cold mug, cold root beer, cold ice cream) you get a situation wherein the thermal boundary layer between the root beer and the ice cream freezes creating a thin crispy layer of creamy root beer ice. Frozen edges are a bonus: not only do you get root beer and ice cream, you also get small chips of root beer popsicle that break away from the boundary layer.

After the mug, you need two additional items: a straw (preferably bendy), and an iced tea spoon. The iced tea spoon is key: without the additional length you'll find your spoon slipping into the chilly depths of your RBF. If you happen to be a proponent of the old-timey paper straws, feel free to use those, but keep about 4 on hand for every float as they tend to collapse in a soggy mess every few minutes.

Iced tea spoon and plastic bendy straw

5. The Process
Some restaurants will serve an RBF pre-mixed. This is very wrong. An RBF should be served as follows:
  • One frosty mug containing the correct volume of ice cream, one straw and one iced tea spoon
  • One bottle/can of root beer on the side.
It is very important to be able to control the addition of root beer to your liking. Personally I like to add the root beer in small increments: pour the root beer over the ice cream until it foams to the top of the mug, stop, slurp a little root beer, eat a little ice cream, and repeat.

6. The Ineffable
Perhaps the most important "ingredient" in making the perfect RBF is a combination of ineffable factors that you can neither control nor fully account for. You could put all of the right ingredients together at the perfect temperature and ratio and yet still not fully enjoy yourself because of the setting, your mood, the time of year, etc. Similarly, you can occasionally get an RBF that isn't well made, but it hits the spot like nothing else beacuse it's 100° out and you just hiked 15 miles.

The best RBF I ever had in a restaurant was in Taos, New Mexico at The Bent Street Deli. They used two local ingredients: Blue Sky root beer (which I like, but isn't a particularly good RBF root beer) and Taos Cow vanilla bean ice cream (very, very good). The mug wasn't chilled, in fact it was a shake glass not a mug, and they were a little skimpy with the ice cream. But I had just had a really amazing morning, the weather was gorgeous, I think Maggie and I had just been giggling at the Peruvian pan flute band outside that seems to follow us everywhere around the world, and at that moment the RBF was just perfection. We went back a few years later, and the RBF was the same but somehow not as good as that first time.

So that about wraps it up: good vanilla ice cream, a balanced fully chilled root beer, the golden ratio, a frosty glass mug, a plastic bendy straw, an iced tea spoon, and the right time and place. Put all of these together and you will have achieved the perfect RBF. If you're already an RBF fan, hopefully this has given you renewed confidence to make one at home; if you're a root beer hater (or suspect you might be), I hope this will convince you to give it a shot - it's worth it. Enjoy!

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