Proclaiming that your product contains secret ingredients is a tactic as old as marketing itself. These seven restaurant chains, drink manufacturers, and food companies have exploited the fact that "the unknown" will always be more exciting than, "just some mayo and paprika."
1. Big Mac Special Sauce
While not explicitly secret, the "special sauce" found in McDonald's Big Macs is the most mysterious ingredient of its "two all-beef patties, special sauce, lettuce, cheese, pickles, onions—on a sesame seed bun." In 2012, McDonald's executive chef Dan Coudreaut released a YouTube video explaining how to make a Big Mac at home—and how to make your own special sauce. Confirming many folks' suspicions, the sauce is just a variation of Thousand Island dressing: mayonnaise, sweet pickle relish, yellow mustard, white wine vinegar, garlic powder, onion powder, and paprika (although, depending on the country in which it's sold, the restaurant throws in some preservatives and other stuff you'd be more likely to find in a chemist's lab than at a market).
2. Bush's Baked Beans Secret Recipe
Bush's Baked Beans' ad campaign centers around Jay Bush and his corporate snitch of a dog, Duke. According to Duke's self-penned bio on their website, "Back when Jay shared the Secret Family Recipe for Bush's Baked Beans with me, his best friend, he didn't know that I could speak. And ever since, I've been trying to sell the recipe."
The original recipe was invented in 1967 and a copy of Bush's recipe book (minus the actual baked beans recipe), is on display at their visitor’s center in Tennessee. Why is it kept secret? Try to think of another company's baked beans ad, and therein lies your answer.
3. Coca-Cola's "Merchandise 7X"
Coca-Cola's long-guarded "secret formula" has a weapons-grade name, "Merchandise 7X," and enough cloak-and-dagger lore to make Ian Fleming blush (he died in 1964, so that's a whole lotta lore). The recipe famously sits in a bank vault in Atlanta, and ad campaigns have focused on how only two company execs have access to two separate halves of the secret formula (this isn't true).
In 2011, This American Life uncovered an alleged version of the original formula (or a precursor to it) that was copied by Coca-Cola inventor John R. Pemberton's friend. This document wasn't hiding in a bank vault, but in a newspaper—in 1979, The Atlanta Journal and Constitution printed a photo from an old notebook that, upon close inspection, seemed to match the famous secret formula. You can check out the recipe here (and yes, it includes FE Coca, a.k.a. the fluid extract of coca leaves).
4. Dr Pepper's 23 Flavors
If urban legend is to be believed, Dr Pepper is just a soda-fied prune juice. If Dr Pepper's website is to believed, this is flat-out untrue. "Dr Pepper is a unique blend of natural and artificial flavors," they assert. "It does not contain prune juice." Then what does it contain? The soft drink boasts 23 flavors, and the specifics of these is considered "proprietary information" by the company.
Keep in mind that "flavors" doesn't necessarily mean "ingredients," so it could all be subjective. A quick Google search will uncover some guesses (although we're not sure apricot is any more refreshing than prune juice).
5. Colonel's "Secret Blend of 11 Herbs and Spices"
In 1940, Colonel (née Harland) Sanders whipped up a "secret blend of 11 herbs and spices" for his now-ubiquitous Kentucky Fried Chicken. The recipe is locked in a vault at the company's headquarters, and it's said that the ingredients are made and processed by separate manufacturers who are unaware of what the others are producing in order to prevent the mysterious concoction from ever being revealed.
In their ingredients list, KFC merely lists this as "Secret Original Recipe Seasoning." However, for his book "Big Secrets," William Poundstone took a batch of the Colonel's chicken to a lab for testing. According to Poundstone (via LiveScience), "The sample of coating mix was found to contain four and only four ingredients: flour, salt, monosodium glutamate, and black pepper. There were no eleven herbs and spices—no herbs at all in fact."
6. Barr's Irn-Bru
Scottish soft drink Irn-Bru was invented in 1901, and its secret recipe "is held under lock and key in a vault in Switzerland." According to their website, only three people know the recipe: Former Chairman Robin Barr, his daughter and Legal Affairs Manager Julie Barr, and one other board director "whose identity remains confidential." Irn-Bru does concede that iron is one of the drink's ingredents (hence the name).
The legend of this liqueur is long and complex, and it goes something like this: In 1605, the Marshal of King's Henri IV artillery gave a secret manuscript for an "Elixer of Long Life" to the monks of a monastery outside Paris. The monks couldn't immediately decipher the combination of 130 herbs, but in the 18th century the recipe was sent to a separate monastery where its apothecary, Frère Jerome Maubec, learned how to make a drink from the list. In the years that followed, the liqueur underwent changes to produce different varieties (green, white, and yellow), but Chartreuse is still made by monks—and the recipe is still secret—to this day.