What's the Best Way to Keep Milk Fresh?

Everyone knows that kissing a frog might make a prince materialize, but unless you're Russian or Finnish, you probably didn't know that frogs have another (alleged) magical ability: They can keep your milk fresh.

According to Russian folk belief, putting a frog in milk helps keep it fresh; there's actually a scientific basis for this, as a frog's skin secretes antimicrobial compounds.
According to Russian folk belief, putting a frog in milk helps keep it fresh; there's actually a scientific basis for this, as a frog's skin secretes antimicrobial compounds.

According to folk beliefs, dropping a frog into your milk can keep it from spoiling (the milk, not the frog). It might sound like an old wives' tale, but there's actually some science backing up a centuries-old custom that fell out of favor thanks to electricity and refrigeration. The reason is this: Frog skin carries many antibiotic substances known as peptides, which the amphibian secretes on a regular basis. Of course, different frogs have different secretions, some of which could even be harmful. The traditional frog species used to preserve milk is the European common brown frog (Rana temporaria), which can be found throughout Europe and northwest Asia. Research has shown that its skin boasts more than 100 peptides, including some that are as potent as prescription medications.

"These peptides could be potentially useful for the prevention of both pathogenic and antibiotic resistant bacterial strains, while their action may also explain the traditional experience of rural populations" that employed the frogs in milk, the researchers wrote.

Hopped up on frog facts:

  • Evidence suggests that frogs might have existed on Earth at least since the time of dinosaurs, or roughly 200 million years.

  • The goliath frog of West Africa can grow to lengths of 15 inches (38 cm) and weigh 7 pounds (3.2 kg).

  • Some glass frogs of Central and South America have translucent skin through which their hearts can be seen beating.

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    • According to Russian folk belief, putting a frog in milk helps keep it fresh; there's actually a scientific basis for this, as a frog's skin secretes antimicrobial compounds.
      According to Russian folk belief, putting a frog in milk helps keep it fresh; there's actually a scientific basis for this, as a frog's skin secretes antimicrobial compounds.