Amid the overwhelming presence of blue and white mold, only two burgers remained remarkably intact. The main characters are none other than McDonald's Big Mac and Lotteria Bulgogi Burger.

The Asia Economy food and beverage team has been observing the signature burgers of six brands?McDonald's, Mom's Touch, Lotteria, Burger King, KFC, and Five Guys?at room temperature for three weeks. Most of the burgers have decayed rapidly.

Condition of Five Guys Bacon Cheeseburger after 3 weeks since starting the hamburger rotting experiment. Photo by Dongjoo Yoon

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The burger that decayed the fastest was the Bacon Cheeseburger from Five Guys. One week into the experiment, on the 7th, white mold began to appear on the bun, beef patty, and tomato, and the cheese started to melt?these were the first visible changes among all the burgers.

As of the 28th, the top of the bun was completely covered in blue mold. By the second week, the bun was more visible than the mold, but now more than 70% of the surface is covered in mold. The mold itself has changed in appearance. The once fluffy mold started to clump together due to moisture inside the container, making it hard to recognize the original shape. A large, cloud-shaped gray mold grew on the patty, creating a spectacle of blue, white, and gray mold. Curiously, the melted cheese still remained intact.

Burger King Whopper condition after 3 weeks of hamburger rotting experiment. Photo by Dongju Yoon

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By the second week, the products that showed the most visible decay after the Bacon Cheeseburger were KFC's Zinger Burger and Mom's Touch's Thigh Burger, both of which use chicken patties. But the ranking has changed. The Whopper from Burger King, which showed little change during the first week, began to develop mold in the second week, and now the top of the bun is completely covered in white mold. It looks as if powdered sugar has been sprinkled all over, with no gaps left uncovered by mold. As moisture increased, droplets began to form inside the plastic container. Looking at the bottom of the bun, moisture and mold could be seen between the folds. As the bun collapsed, it covered the patty and vegetables, making it impossible to check the inside, but there were no signs of mold between the bun layers.

The change in ranking brought to mind Burger King's advertisement. In 2020, Burger King USA released a 45-second global ad on its official YouTube channel, showing a Whopper covered in mold after 34 days. With the English slogan "The beauty of no artificial preservatives," the ad highlighted that the Whopper is made from eco-friendly ingredients. In the video, after 34 days, the entire burger?from the bun to the vegetables and patty?was covered in dark blue mold. Asia Economy plans to directly compare the Whopper in the experiment to the one in the ad on November 9, exactly 34 days after the experiment began.

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The Thigh Burger looked similar to how it did in the second week. However, the dark blue mold on the bun and chicken patty grew larger, resembling a mushroom-shaped atomic bomb. The inside of the container was filled with moisture, with droplets running down the sides. The Zinger Burger also remained largely unchanged. The mold, which had been concentrated on the chicken patty, spread to the bun, but only one side was severely affected, while the other side still maintained the original appearance, with the chicken surface clearly visible.

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For the so-called 'immortal' McDonald's Big Mac and Lotteria Bulgogi Burger, external changes were still slow. The volume of the Big Mac bun remained surprisingly unchanged, and unlike the other products, no moisture appeared on the walls of the container. It seemed to stay dry throughout. On the eighth day of the experiment, a small spot of white mold, about the size of a pinky nail, appeared on the bottom patty and bun of the Big Mac, and it still looked the same.

At this rate, the rumor that "hamburgers don't rot" may not be entirely baseless. The Bulgogi Burger also showed no significant changes compared to the second week, even though a small spot of mold had started to grow on the edge of the patty and seemed to be spreading to the bun. The bun in contact with the plastic bottom of the container was where the rot was spreading, but the patty and the top of the bun still maintained their original appearance, just like at the start of the experiment.

As the hamburger rotting experiment entered its third week, the studio temperature ranged from 16 to 22 degrees Celsius, and humidity ranged from 37% to 84%. Asia Economy will continue to observe under the same conditions to see which burger lasts the longest without visible decay.

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