The Scientific Reason Why McDonald’s Fries Are So Good

You're not the only one who can't stop eating them. Ever wondered why?

Everyone knows what it’s like to eat McDonald’s french fries. As soon as you pick up the box, you get a whiff of that unmistakable frying oil scent reminiscent of drive-thru windows and fast-food counters.

You grip that iconic red box with the famous arches on the front, holding a generous handful of stiff golden sticks. Then you take the first bite and hear that satisfying crunch through the crispy outer layer, with the salt so discernible you can feel it leaping onto your tongue. And then the fluffy, soft inside: some magical combination of potato that manages to taste a million times better than any fries you’ve had before.

They’re warm and satisfying, and you polish them off one by one. Before you know it, the whole box is gone.

It makes you wonder: What do they put in McDonald’s fries to make you eat your way to the bottom of the carton? As it turns out, it’s not just one thing—it’s a spellbinding combination of things, creating a taste experience unlike any other fast-food chain’s. To make it easier to digest, we’ve broken down the secret McDonald’s recipe into three components.

How the Smell of Oil Affects the Flavor

Scientists believe our sense of smell might be responsible for up to 90% of perceived flavor. If you ever doubt this statistic, just think about how unappetizing food seems when you have a cold and your nose is blocked.

Without that delicious aroma, McDonald’s french fries wouldn’t taste as good. This smell—and the taste that comes with it—is almost exclusively from the oil in which the fries are cooked.

Like most fried foods, McDonald’s fries are cooked in canola oil. But this didn’t used to be the case. Beef tallow was initially used because the supplier for the chain couldn’t afford vegetable oil.

As health concerns over saturated fat grew in the 1990s, McDonald’s finally made the switch to vegetable oil. Unfortunately, customers noticed that the fries didn’t taste how they used to. To mimic the chain’s original oil blend, the oil is laced with natural flavoring to replicate that mouthwatering smell.

In other words, the delicious scent we know and love is actually the smell of potatoes cooked in beef fat, an aroma so powerful it makes the fries seem even tastier!

Salt, Sugar and Fat

The smell might get you to take that first bite, but it’s the taste that brings you back for more. While homemade french fries don’t require much more than salt, potatoes and oil, McDonald’s has mastered the art of combining ingredients to bring that treasured sensation to the finished product. The main players? Salt, sugar and fat.

Including one or two of those in a recipe makes it good, but having all three sends it over the top. The perfect equilibrium of these ingredients is known as the “bliss point.”

American market researcher and psychophysicist, Howard Moskowitz, stated that a “bliss point” is the point where the levels of saltiness, sweetness and richness are perceived as being just right. Within the food industry, this combination created a wave of craveable and addicting foods.

Eating those tasty McDonald’s fries even releases dopamine in your brain, the neurotransmitter that triggers feelings of pleasure. So how does McDonald’s do it? In addition to frying and seasoning the fries, McDonald’s coats them in dextrose, a form a sugar.

The Right Potatoes

The crunch, or more specifically the mouthfeel, is the way something feels as you eat it. How hard is it to break with your teeth? What does the texture feel like on your tongue? Everyone judges mouthfeel differently, but McDonald’s has clearly found one that appeals to most of us.

The most common potatoes used for McDonald’s fries include the Russet Burbank, Russet Ranger, Umatilla Russet and the Shepody. These potatoes are known for being fluffy on the inside while still maintaining a crunch on the outside.

Their website states that “The suppliers we work with first peel, cut and blanche the potatoes. They then dry, partially fry and quickly freeze the fries for our restaurants. Once in our kitchens, we cook them in our canola-blend oil so you can have them crispy and hot—just the way you like them.”

Maybe that’s what separates McDonald’s fries from others in the fast-food industry; knowing what customers love about their fries and delivering seamlessly every time. When you put all those details together, it’s no mystery why these fries are addictive.

Want to learn more secrets about this classic chain? Check out McDonald’s secret menu.

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