The Art of the Brew
What brewing does to the coffee
Coffee can be brewed in four ways: gravitational feed, decoction, infusion, or pressurized percolation. Brewed coffee, if kept hot, will quickly deteriorate in flavor, and reheating it will tend to give it a "muddy" flavor. Even at room temperature, deterioration will happen; however, if it is kept in an oxygen-free environment it can last at room temperature.
Different Coffee Brewing Methods
Espresso is prepared by pushing hot water through a layer of compacted ground coffee, contained in a port-filter. Espresso is finely ground coffee that is very concentrated in taste, with a lot of aroma, body, and a punch in flavor. It contains a lot of coffee oils and solids. The most distinctive features of espresso are the foamy layer on the top, and how this cup of joe can have a very low volume.
Drip coffee is the most popular preparing method in North America. The method involves pouring hot water over ground coffee beans. The brew is strained with a paper filter, or a metal or plastic mesh. Coffee from a drip brewer is clear and clean, with a high ratio of caffeine taken out per spoon of ground coffee.
French press is an easy coffee brewing device with a beaker and a filter. When preparing it, you pour hot water over coffee grinds and let it sit for a few minutes. After the steeping is over, the filter is pressed down to separate the grinds.
How do Different Brewing Techniques Bring Out Different Flavors in the Coffee?
Drip- This is brewed through a filter containing the ground coffee beans as boiling water is “dripped” on top. The filter leaves behind the ground coffee beans as liquid passes through and into a coffee pot that is then used for serving. Making drip coffee takes more time since hot water is in contact with the ground coffee beans for a longer period.
French Press - French pressed coffee is to be consumed immediately after brewing. Coffee drinkers believe that making French press coffee produces a stronger flavor compared to a drip coffee machine since it allows the oils from the ground coffee beans to mix with the water. A French press has a glass with a mesh filter inside so that it separates the ground coffee from the hot water. When its ready, a lever is pushed down which strains and separates the coffee grounds from the brewed coffee, leaving the grounds on the bottom and liquid coffee above the filter. Before brewing with a French press coffee maker, coffee grounds should be a medium or coarse grind to have a good flavor, and to prevent them from passing through the filter.
Espresso Machine - Espresso beans are ground much finer than drip and French pressed coffee, and still has the texture of powdered sugar, which are then brewed. First, the coffee grounds are placed into a portafilter. Then, the brewing process begins as water is pressurized through the beans to produce a dark liquid. Espresso machines are designed to force a small amount of hot water through the coffee grounds at a very fast speed, and one shot of espresso can take as little as 20 seconds to brew. Espresso is more pungent in taste than the previous two brewing methods, and is also creamier because of the crema that is produced from the brewing method.
What Temperature Should you Brew at?
The temperature that you should brew at should be between 195 F and 205 F. The closer to 205 F the better. Boiling water 212 F should never be used, as it will burn the coffee. Water that is less than 195 F will not extract properly.
How Brewing Affects Bitterness or Lack Thereof in the Coffee
You're using an incorrect grind size –By grinding coffee beans, you change how the flavor compounds will dissolve, which basically means that if it's ground too much you end up with sour tasting coffee. If they're too finely ground, you risk an over-extracted, very bitter coffee.
The water is too hot - If it's too hot you'll extract the bitter compounds. 195°F to 205°F is ideal in able to have a good cup of coffee. This means to not let your water overboil, and let it sit for just a minute before pouring over your grounds.
The Science and Chemical Reactions that Occur During the Brew
When the coffee beans are first dropped into the roaster, a drop in the temperature is occurring as the beans rapidly absorb energy. This is where most of heat energy goes towards the evaporation of water. In the early stages of roasting, colored plant compounds such as chlorophyll, etc, begin to decompose and the coffee bean changes from a green color to a more yellow color. This color change has little changes in aroma from a grassy aroma to more toasty smell. As the temperature increases, water that is within the bean begins to form steam and a pressure gradient is created within the coffee bean. As more pressure builds the pressure destroys the cells within the bean to create its "first crack".