Why People Brew Their Coffee With Eggshells

When it comes to delicious breakfast duos, you can't go wrong with the classic pairing of coffee and eggs. But have you ever had coffee with eggshells? No, we're not talking about drinking coffee with actual eggshells; we're referring to the practice of adding eggshells to the coffee ​before​ brewing it.

As it turns out, brewing coffee with eggshells can make your cup of joe taste less bitter. According to Cook's Illustrated, eggshells contain calcium carbonate. It's an alkaline substance, so it can reduce some of the acids in coffee, aka the stuff that makes coffee bitter in the first place. The result is a more mellow cup of coffee.

To fully understand this trick, it might help to brush up on the pH scale. Here's how it works: The pH scale ranges between zero to 14, with seven being neutral. Substances with a pH higher than seven are alkaline. Meanwhile, substances with a pH lower than seven are acidic. Coffee has a pH of five, according to Clemson University.

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Since calcium carbonate is alkaline and coffee is acidic, they're on opposite sides of the pH scale. But when they're combined, the alkalinity of calcium carbonate helps neutralize the acidity of coffee, thus reducing its sharpness.

Ready to try this hack? Roasty Coffee recommends using the shell of one egg for every four cups of coffee. Gently wash the shells to remove leftover egg, then crush them up and add them to your filter along with coffee grounds. (You can do this with any brewing technique, BTW.) Brew the coffee as usual and enjoy.

If you're not loving the idea of adding eggshells to your coffee — or if you don't eat eggs — there are other ways to make coffee taste less acidic. Try the following techniques:

• Choose light roast instead of dark roast.
• Grind beans into coarser granules.
• Make weaker coffee by using more water or less coffee.
• Add a dash of salt to the brewed coffee.

When all else fails, there's always the option of adding creamer and/or sugar. Cheers!