Many different factors can influence the rate and extent to which coffee is extracted. Factors such as grind size, coffee to water ratio, and brew temperature are all interlinked and together are responsible for coffee extraction. When one factor is adjusted, all others are affected. This is why you need to follow that-recipe-you-found-on-the-Internet religiously. Brewed Chemex Coffee This article will discuss some of those main variables which govern how strong or weak a brewed cup of coffee is, as well as whether or not a brewed coffee is over or under extracted in a bit more detail.
Does Finer Grind Make Stronger Coffee?
Espresso brewing calls for a finer grind compared to other brewing methods such as filter coffee or French press. Espresso coffee is also thought to be stronger than the other methods. This, among other facets, lends to the belief that finer grind means stronger coffee.
Coffee is ground finer in order to increase the surface area of the bean that is in contact with water during extraction. This increased contact causes greater extraction. Therefore, if coffee is ground finer and all other brewing parameters are not adjusted, finer ground coffee will extract more coffee properties to be dissolved into the water, resulting in a beverage with a greater TDS which is therefore stronger. However, if more water is added to the recipe, a coffee that is brewed using finely ground beans would have a lower level of TDS and would be a weaker tasting product.
What Is the Best Coffee Grind Size?
As the coffee industry has developed, it has been discovered that specific grind sizes are optimum for specific brewing methods. These sizes are governed by the other brewing and practical elements for each method.
Optimum grind sizes for standard brewing methods are as follows:
Turkish coffee is traditionally ground extremely fine in order to achieve an intense, strong and dark brew. A specific Turkish grinder is usually required as standard industry grinders do not have the capacity to grind finely enough.
Espresso coffee is ground finer than drip coffee because of the added element of pressure during brewing, which speeds up extraction. This will be discussed later.
Aeropress coffee grind size falls in between espresso and drip grind size, as Aeropress brewing can be described as an amalgamation of those two brewing methods. Some pressure is added during brewing but not as much as espresso. The filter is also not as fine as a portafilter. Therefore a fine, but not extra fine grind is used.
Drip coffee brewing is reliant on gravity alone for brewing, therefore a coarser grind is required to allow the water to pass through the coffee within the optimum brewing time.
French press coffee is traditionally ground coarse as the French press filter screen is also coarse. Finer coffee grounds would pass through the filter and into the coffee cup. The same is true for percolator brewing. However, with good quality equipment, a finer grind size can be successfully employed with French pot brewing.
Cold brew is traditionally brewed using a coarse grind, due to the longer cold brewing extraction time and filtration problems. The idea behind coarse grind for cold brew is that cold brew can get over-extracted due to the longer brewing time. This would result in extractiing unwanted compounds in the final brew. However, in my experience, we are only extracting more of the same compounds, and by diluting your final cup a little more, you can get a great cup.
Extraction and Coffee Brewing Temperature
Brewing temperature is perhaps the most important factor for coffee extraction. Incorrect temperature, more than any other factor, is usually responsible for over-extraction. The other brewing elements also play a role in over extraction, but normally in conjunction with incorrect temperature, not as stand alone entities.
Standard optimum coffee brewing temperature is between 195 and 205 degrees Fahrenheit and varies slightly from brewing method to brewing method. If coffee is brewed with water that has been directly boiled in a kettle, the coffee will be burnt and over extracted.
How Do You Tell If Coffee is Over-extracted or Under-extracted?
You can tell if coffee is over-extracted or under-extracted mainly by taste. Different flavor profiles are extracted at different stages during brewing. Fats, oils and acids are extracted first, followed by sweetness, followed finally by bitter notes which consist mainly of plant fibers.
Why is Coffee Over-extracted?
Coffee is over-extracted due to one or more of the following: grind is too fine, brewing time is too long, temperature is too high.
A bitter taste in coffee is due to over-extraction of the bitter fibers from the coffee beans.
Strong, well-extracted coffee will have lots of intense flavors that feel balanced to taste, without any one flavor being overwhelmingly dominant.
Roast and Extraction
Roast is another important factor to be considered when brewing. As with brew time, roast time also influences the coffee extraction. Darkly roasted coffee that has been roasted for longer will release more coffee properties during extraction. The opposite is true for lightly roasted coffee. Therefore, brewing factors need to be adjusted to the specific roast being used.