Staying Pretty: Investigating the immortality of MacDonald’s hamburgers

We’ve all heard the theory that MickeyD’s burgers are so full of preservatives that, even when left out of the fridge for years, they still look the same. Never to mould, rot, or decompose.

The most famous ‘immortal’ burger was originally purchased in 1996 by Karen Hanrahan, blogger on the Best of Mother Earth. It’s not alone – immortal burgers are a dime a dozen, it seems.

As Hanrahan says “Ladies, Gentleman, and children alike – this is a chemical food. There is absolutely no nutrition here.”

Fed up with sensationalism, J. Kenji López-Alt, manager of the blog Serious Eats, decided to give this mystery a more scientific flavour. He proposed five theories as to why the burgers didn’t decay: preservatives, high salt content, dehydration, an absence of mould spores in the vicinity of the burger, or an absence of air where they are stored.

The last is wrong, obviously. As is the second-to-last. Mould spores are everywhere. As for preservatives, the labels state no major difference between a regular store-bought loaf and a Macdonald’s bun.

So López-Alt embarked on an investigative quest. He mixed home-made and MickeyD-obtained patties and buns, varied the salt level, and varied the mode of storage. To top it off, a Quarter Pounder was added for extra comparison.

The results? The Macdonald’s hamburger didn’t grow mould (as expected). But neither did the homemade stuff. In fact, the only mould visible was a small splodge in the very centre of the Quarter Pounder. This strongly supports theory three – that mould doesn’t grow because the burgers simply dehydrate too fast. They become ‘burger-jerky’.

 “Because of the larger size of a Quarter Pounder, it simply takes longer to dehydrate, giving mold more of a chance to grow…  How do you think beef jerky is made?”

Indeed, once the Quarter Pounder dehydrated sufficiently, the mould stopped growing. And when MacDonald’s burgers were kept in sealed plastic bags to trap their moisture, mould grew within a week. Seems those burgers are confined to the mortal realm after all.

Let’s stop the chemical and preservative bashing… the culprit here is moisture.IMG_0075

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Lauren Wright

Globetrotting Aussie postdoc on the hunt for science, logic, and humanity. I research metabolism, mitochondria, obesity, type 2 diabetes, and other weighty stuff.

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