There are certain uncontested truths in the world. The sun will come up in the east tomorrow, and set in the west. An apple that falls from a tree will always land on the earth. And rolling a lemon on the counter with the palm of your hand will always produce more juice.
The last one is so ingrained in our collective knowledge what every source I could find states so with impunity. The Joy of Cooking says, “To get the greatest amount of juice out of citrus fruit, roll the whole fruit on a hard surface, gently but firmly pressing it with the palm while rolling.” The New Best Recipe, by the folks over at Cook’s Illustrated magazine says almost exactly the same thing. This bit of information, along with the notion that room temperature citrus will yield more juice than refrigerated fruit, is pervasive. These “truths,” particularly in the food and drink world, have long gone on uncontested. If something appears in as venerable a tome as the Joy of Cooking, one shouldn’t have to think twice about it, right?
However, I was skeptical. Common sense told me that there is finite amount of juice inside of a lemon, and that no amount of temperature manipulation or massage therapy would convince a little lemon to give up something it didn’t have. So I set out to discover for myself if there was any truth to this “fact.” I am a man of science, after all.
I took four groups of fifteen lemons each, and distributed them by weight as evenly as I could amongst each group. One group was the control: straight from the fridge without any rolling at all. Group two was refrigerated and rolled. The third group was not rolled but left out over night at room temperature. And the fourth group, which by most accounts should have yielded the most juice, was left out overnight at room temperature and rolled.
I juiced each group and carefully weighed and measured the volume of the resulting group’s juice. I then calculated the average amount of juice per lemon. The results? Astonishingly, the fifteen lemons in the control group yielded the most juice. The question is… why?
A quick examination of the experiment shows a reasonable explanation. Lemons left on the counter overnight at room temperature are certain to experience a small amount of evaporation. Let’s face it, those lemons have pretty permeable skins, and it only seems right that some of the water contained therein would be able to pass through the skin as water vapor.
Similarly, one would expect that rolling the lemons on the counter would express some of the liquid through the skin. Indeed, when I tried rolling them on some thin tissue paper placed on top of the counter, the paper became damp with juice.
What does it all mean? Well, this newfound knowledge has changed my behavior and sped up my time spent juicing lemons at home. With a good mechanical juicer and a strong hand I can squeeze every last drop of citrus juice without any concern I’m missing out.
These days, there is so much information out there that it can be challenging to know the difference between right and wrong. When should we embrace age-old techniques and when are they worthy of re-examination? We can be tempted to become jaded when even our old heroes, such as those old books we take such pride in clinging on to, turn out to be full of hot air. But for me, there is a limitless joy in discovering the truth about food and drink, and doing so only strengthens my resolve to not only make better cocktails, but also to make cocktails better.
Jeffrey Morgenthaler is the bar manager at Pépé le Moko and Clyde Common, the acclaimed gastropub at the Ace Hotel in Portland, Oregon. He is also author of The Bar Book: Elements of Cocktail Technique.