The mystery of Blue Moon ice cream

Instagram is filled with the stuff. It's filled with postcard-perfect pictures of toddlers and their enraptured guardians advertising things like "it's a blue moon kinda day," "first blue moon of the season," and "still obsessed with it 25 years later." For lack of a better word, "celestial" is the only way to accurately describe the iconic Midwestern frozen treat. No one can agree on its flavor profile. Vanilla, pistachio, amaretto, almond, coconut, nutmeg, pineapple, cantaloupe, raspberry, ginger, lemon, licorice, Froot Loops, the milk that's leftover after you finish a bowl of Fruit Loops, Fruity Pebbles, Trix, cotton candy, frosting, bubblegum, peeps, gin, and blue curacao? People have linked all of these flavors with the ice cream (via Whoo New and Groupon Guide to Chicago). 

Then again, self-professed food scientist Eran Evans says on Quora, "There are some brands on the market that are just vanilla ice cream with blue food coloring." Chicago Tribune reporter Nara Schoenberg, who tried and failed to track down the flavors and origins of the mythical treat, notes that Blue moon ice cream has been popping up in American newspapers since at least 1936. Today, different companies keep their proprietary blends a secret (via Atlas Obscura). But for at least that long, no one has been able to agree upon what's in it. 

"Trying to figure out what blue moon tastes like is like trying to figure out why Mona Lisa smiles," writes one Groupon editor.

Want to take a stab at Blue Moon ice cream? This might be as close as you'll get

Can we thank Bill Sidon, Petran Products' chief flavor chemist during the 1950s, for the flavor, asked The Chicago Tribune? Sidon, a Jewish chemist who spoke five languages, loved motorcycles and escaped Nazi Germany in 1939, might be behind Petran's recipe. And Petran was the first company to trademark it. But, as Blue Moon-flavored ice cream was circling in newspapers before the 50s, Sidon probably wasn't the originator. Even if he was, the company that later acquired the trademark, Edgar A. Weber & Co, won't tell us what he put in it.  

They did, however, give us one hint. The owner of Edgar A. Weber & Co., Andrew Plennert, said: "A colorless version of Blue Moon is used in the pharmaceutical and beverage industries to hide bitter or harsh tastes in products such as yogurt" (via the Associated Press). Whoo New did a little bit of digging. They suggest that a principal ingredient may be castoreum, a natural flavoring excreted from a beaver's pelvic sacs. (Yum?) 

We couldn't track down a recipe with beaver excretions included. If you are nonetheless eager to try to replicate Blue Moon ice cream yourself, Serious Eats recommends that you freeze a custard you've made out of egg yolks, sugar, heavy cream, whole milk, vanilla pudding mix, raspberry flavoring, lemon oil, vanilla, and blue gel food coloring. Or, you know, just keep searching for the elusive original recipe.