Russians Once Dipped This Frog In Their Milk Jars—Here’s Why

By Scott Travers, Contributor. I write about the world of biology.
Nov 25, 2024, 08:47am EST

Long before we had the luxury of storing milk in refrigerators, households in Russia and Finland had a more unconventional means of preservation: they would drop a frog in the bucket of milk.

All they knew was that this frog—the European brown frog or Rana temporaria—would keep their milk from turning sour. It might sound strange to modern ears, but this practice was a clever and effective, albeit accidental, application of the frog’s natural defenses.

In stark contrast to the toxic or psychedelic amphibians in the wild, Rana temporaria flaunts a treasure trove of powerful antibiotic substances. Today, scientists are diving deeper into the antimicrobial properties of Rana temporaria’s skin, uncovering a rich arsenal of bioactive compounds that go beyond milk preservation.

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The frog’s skin produces a variety of antimicrobial peptides (AMPs) that serve as its primary line of defense against pathogens, according to a November 2012 study published in the Journal of Proteome Research. These peptides are especially effective against a wide range of bacteria, including some strains known for their resistance to conventional antibiotics.

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