You have brewed a nice pot of coffee and have enjoyed one cup. Then the pot sits there and the coffee cools off while you are busy with your work or chores at home. When you want more coffee do you throw out the old pot and brew up a new pot or do you simply reheat your coffee? In that regard, what happens when you reheat coffee?
How Reheating Coffee Affects Flavor
When you let coffee cool off and then reheat it, the reheating process causes a breakdown of a coffee constituent, chlorogenic acid, and turns it into caffeic acid and quinic acid. These new ingredients lend a bitter taste to the reheated coffee. This breakdown happens because of reheating and it makes little difference if you reheat your coffee on the stove or in the microwave. Brief heating in a microwave may have a little less effect on coffee flavor.
What To Do About Avoiding Cold Coffee
Because reheating coffee messes with the flavor, the best way to drink your coffee from one brewed pot over an extended period of time is to keep it warm. Use an insulated mug or carafe. If you are traveling you may with to use a thermos bottle.
Reheating coffee, whether in the microwave or on the stovetop, leads to increased bitterness due to the breakdown of chlorogenic acid into quinic and caffeic acid.
Using a microwave for reheating is slightly better than using the stovetop as it retains more flavor.
The best way to keep coffee hot without reheating is to use a high-quality insulated mug or carafe. If you are traveling or otherwise on the go, consider pouring your how coffee into a thermos bottle.
Longer Term Storage of Brewed Coffee
If you want to keep your brewed coffee fresh past a few hours an alternative is to put in the sealed container and place in the refrigerator. It will keep for up to three days but by the third day it will start to lose flavor. If you have added milk or cream to your coffee that shortens the time to a few hours. Basically, if you want great coffee with optimal taste and aroma it is best to brew enough for the day and rebrew every day. Although coffee bean and ground coffee lose their freshness over time, we are not talking about a matter of hours.
Storing Coffee
Your best bet for retaining excellent flavor for your brewed coffee is to brew only enough coffee for what you are going to drink right away. Thus, the issue for fresh taste and aroma is proper storage of your green coffee beans prior to roasting, or your roasted whole coffee beans prior to brewing. In each case you want a cool and dry location away from sunlight. The first caveat is not to put your coffee in the cupboard above the stove where it is never really cool or dry. Green coffee beans can remain fresh for up to three years with proper storage and roasted coffee beans for at least a couple of months. With properly stored coffee to start from you can make brew enough coffee for what you need immediately and avoid reheating with its bitter taste.