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McDonald's Big Mac Never Grew Mold After Sitting Out For a Year, Customer Claims

A TikToker launched a viral experiment last year centered around McDonald's famous Big Mac.
FACT CHECKED BY Justine Goodman

Have you ever wondered how a McDonald's burger would fare after sitting out for a whole year? One customer recently conducted an experiment to find the answer to that question—and the results left fellow McDonald's fans in shock.

Naa Adjeley, a medical herbalist and TikToker (@tsofanye) who lives in the United Kingdom, kicked off the trial on Feb. 2, 2023, by setting up a McDonald's Big Mac (590 calories) and French fries (320 calories per medium order) on a plate. At the time, she said she wanted to see how long it would take for the classic fast-food burger to grow mold. But in a recent update posted a year and three weeks after she began the experiment, the TikToker inspected the food and found it was all still completely mold-free.

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She was particularly baffled to see that some of the shredded lettuce on the Big Mac had retained its green color and some of its moisture throughout the whole year.

McDonald's Big Mac TikTok experiment
@tsofanye / TikTok

"People, tell me how that is possible," she said, adding later in the video that she had not tampered with the lettuce in any way. This inspired Adjeley to start another experiment to see how long it would take for a McDonald's salad to brown and deteriorate while sitting out on a plate.

Adjeley's update video has racked up a whopping three million views and thousands of comments from TikTokers, many of whom were baffled by the longevity of the burger and fries.


Its Unbelievable that the Big Mac has stood the test of time and the lettuce is still green. So I decided to expand the experiment and buy McDonalds Salad – what is going on! #mcdonalds #mcdonaldsmagic

♬ original sound – Naa-Adjeley

"Lasted longer than a lot of my relationships," one commenter quipped.

"I'm never eating McDonald's again," another wrote.

Adjeley wasn't the first—and probably won't be the last—to conduct this type of experiment with McDonald's food. Decades ago, one customer in Iceland stashed a McDonald's cheeseburger (300 calories) and fries for years, but they remained mold-free and relatively intact the whole time, reported.

These experiments have made some customers suspect that McDonald's food never decomposes, but the chain attempted to debunk those rumors in a 2020 statement.

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"In the right environment, our burgers, like most other foods, could decompose. But, in order to decompose, you need certain conditions—specifically moisture," the statement read. "Without sufficient moisture—either in the food itself or the environment—bacteria and mold may not grow, and therefore, decomposition is unlikely. So if food is or becomes dry enough, it is unlikely to grow mold or bacteria or decompose. Food prepared at home that is left to dehydrate could see similar results."

So, while many consumers find the lack of mold on a year-old Big Mac to be unsettling, it's not necessarily because there's something wildly unnatural about Mickey D's food.

"The reality is that our burgers are made only with 100% USDA-inspected beef," the statement added. "There are no preservatives or fillers in our patties and the only thing ever added is a touch of salt and pepper on the grill."

Zoe Strozewski
Zoe Strozewski is a News Writer for Eat This, Not That! A Chicago native who now lives in New Jersey, she graduated from Kean University in 2020 with a bachelor’s degree in journalism. Read more about Zoe
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