Eggs are one of my favorite foods. They accompany my coffee or tea almost every morning. However, reusing the eggshells for my coffee isn’t something I’d ever consider doing. Maybe you’ve heard of using eggshells and wanted to look into it. Let’s take a look at the most popular reasons for using them in coffee. The eggshells are said to be used for two different purposes. The first is said to reduce the bitterness of the coffee. The second is to remove suspended coffee grounds. Let’s explore these methods. Reasons for Using Eggshells in CoffeeEgg shells are almost entirely calcium carbonate, an alkaline material that can absorb the acid. They also consist of magnesium carbonate, calcium phosphate, and other organic matter. The only possible benefit of adding them to the grind is to raise the coffee’s pH level. Coffee is somewhat acidic but almost neutral so it’s unclear how any change in the pH would be perceived in the mouth. A better alternative that doesn’t have you removing residual egg whites and yolks: brewing a better cup of coffee so that it’s not acidic. Pretty simple. People also use egg shells to settle suspended coffee grounds. With that said, I’m not entirely sure how adding varying sizes of calcium carbonate can settle coffee grounds. Origins of This Brew MethodThe origin of this brew method is unfortunately unknown. However, my Father had some interesting insight that helped shed some light on the added eggshells. He told me about this character called “Chester Goode” from the old Cowboy TV show, Gunsmoke. He said that Chester was obsessed with coffee and even mentions eggshells in a scene when he’s talking to Marshal Dillon. Chester goes on to say “…I think you left the eggshells out of it Mr. Dillon.” Come to find out, there are actually several mentions of eggshells in coffee throughout Gunsmoke. Here’s a clip of the above interaction:This might explain why this brew method is often referred to as “Cowboy Coffee.” Gunsmoke started as a radio series in 1952 but the televised series aired from 1955 to 1975. The show itself though was set in Dodge City, Kansas in the 1890s. So we know that eggshells in coffee grounds at least existed in the 19th century. The coffee plant cites it’s origins to the 11th century in Ethiopia. So it’s safe to say that sometime between the 11th century and the 19th century people decided to re-use eggshells with their brewed coffee. How to Use Eggshells in CoffeeAdding eggshells to coffee isn’t that common anymore. While I’m not a fan of adding them to my coffee, you may be curious as to how to do it. - Note that you can’t use egg shells from hard boiled eggs. When eggs are hard boiled, they release hydrogen sulfide, a sulfur compound that can permeate the coffee grounds. So, assuming you made some eggs for breakfast. Set the eggshells aside. Typically 2 eggs is more than enough. - Wash the egg shells to remove any egg whites or yolk residue.- Crush the egg shells into a more course consistency.- Add the eggshells to the coffee grounds.- Brew your cowboy coffee. These days, due to how much control you have over your coffee there isn’t a need for additional alkaloids to balance acid levels. Coffee itself is already fairly neutral and rates around a 5 on the pH scale. This is around the same level of acidity as a banana. Let that sink in.