Scientists Just Discovered the Secret to Making a Perfect Cup of Coffee

If you have yet to brew a cup of coffee that's as good as what you get at your local café, you're in luck. To help you achieve barista status at home, scientists just discovered the secret to making a perfect cup of coffee: adding water to the beans before grinding them.

The study, which was published in the journal Matter, found that adding water to whole coffee beans boosts the flavor of the drink and cuts down on wasted coffee. According to the research, coffee grinding produces large amounts of static charge. The addition of external water reduces the charge during grinding and promotes particle declumping.

To obtain their findings, the researchers measured the amount of static electricity produced when they ground different roasted coffee beans that had varying processing methods, roast color, and moisture content. They sprayed the beans with different amounts of water before grinding and brewing them into espresso.

The researchers found a correlation between electrification and water content, roast color, and particle size. Lighter roasts produced less charge while darker roasts (which tend to be drier) charged negatively and produced more overall charge. The higher the amount of charge, the clumpier the grounds became.

Next, researchers tested whether grinding identical coffee beans with water changed the way espresso is brewed. When researchers compared espresso made with coffee beans that were ground either with or without water, they found that grinding with water resulted in a longer extraction time and a stronger brew.

"The central material benefit of adding water during grinding is that you can pack the bed more densely because there’s less clumping," senior author Christopher Hendon said in a press release.  "Espresso is the worst offender of this, but you would also see the benefit in brew formats where you pour water over the coffee or in small percolation systems like a stovetop Bialetti."