Why You Should Wait for Your Brewed Coffee

By Cook's Illustrated Published May 2013

When it comes to brewing coffee with an automatic drip machine, let the pot fill completely before pouring that first cup. Here's why.

We know the temptation: First thing in the morning, the coffee is brewing, and you can’t help sticking your mug beneath the spigot on the coffee maker to steal a cup before the pot has finished. But how much does removing some coffee early influence the flavor of the final pot? Armed with an array of coffee mugs and a coffee refractometer, a tool that measures the amount of soluble flavor compounds, or total dissolved solids (TDS), extracted from the beans, we put that question to the test.

As a pot of coffee brewed in our favorite coffee maker, the Technivorm Moccamaster, we took samples from the brewing spout every 30 seconds and measured the TDS in each. As we had suspected, the coffee coming out of the spout at the beginning of the brew time was significantly stronger than the last few drops: 3.93 parts per million (ppm) versus 0.44 ppm, or more than eight times as concentrated. It was also more than twice as strong as coffee from a fully brewed pot (1.54 ppm). Only at the midway point of the brew cycle did the concentration of the sample come close to that of a fully brewed pot.

THE BOTTOM LINE: Hold on to your mug. Most of the flavor in a pot of coffee comes during the early stages of brewing. And if you sneak a cup early on, not only will it be far too strong but you’ll be running off with most of the good stuff and spoiling the pot for others.