Here's What's Really In The Secret Ingredient(s) Of McDonald's Fries

If you're wise enough to know which fast food fries are the most delicious (and it's McDonald's – sorry, sue us), you might have wondered what makes Mickey D's fries just that good. Sure, it might have something to do with the contrast between their crispy outsides and soft insides or the extra-fine salt they're generously doused with (via Thought Catalog). Plus, duh, it's hard to mess up a potato. But the true beauty of the Golden Arches' crown jewel lies within the flavor. For lack of a better expression, they've got it down to a literal science.

You can probably guess what's in a fry: Potatoes. Some kind of frying oil. Salt. But a lesser-known "secret" ingredient is the "natural beef flavor" McDonald's deploys for each and every greasy bite (via NPR). First, a little history: As with most good things (see: chocolate chip cookies, ice cream cones, penicillin, via First We Feast and Discovery.com) — an accidental discovery led to McDonald's fries being cooked in beef tallow or fat beginning in the 1950s. The restaurant's oil supplier at the time couldn't afford the necessary equipment to hydrogenate the vegetable oil to make it last longer, so they decided to substitute in some beef tallow and hope for the best. It turned out that the addition of beef made for a crispier, more delicious fry — and the change stuck (via NPR).

Cut to 1990 and the anti-fat crusaders, and the fast food giant's hand was forced. They cut beef tallow out in favor of pure vegetable oil, which was lower in unhealthy saturated fats, but they kept beef flavor in with "natural flavors" (via Eater). Now, "natural beef flavor" is a standard component of McDonalds' fries (via McDonald's). And though the secrecy surrounding the "natural flavor" industry runs deep — there's probably a flavor mafia out there somewhere (kidding) — we do know a few things about this mysterious beefy addition.

First off, it's probably not made from beef at all. Gary Reineccius, a food chemist, told Eater that it's merely meat-adjacent. "The flavor in beef is created during the cooking process. Food scientists identified the amino acids found in beef, added some very common sugars — starch hydrolysate — put it in a pot, added some citric acid to drop the pH, controlled moisture content, and heated it to the same temperature as meat. Then...*poof* we have meat flavor," he said. Sadly for vegans, it's still not totally animal-free — according to the McDonald's website, natural beef flavor contains hydrolyzed milk as a "starting ingredient." But it sure makes those classic, starchy American favorites delicious.