Manual Coffee Makers
By Rachel Deghuee
''Customers select their coffee maker based on their individual preferences and coffee tastes. Is it possible to design one brewer to rule them all?''
Introduction
The millennial generation is leading the resurgence of craft coffee brewing, with 11 percent of young adults choosing to make craft coffee at home (Link ). Promising customization, compact footprint, and frugality, craft brewing promises the same or better coffee than the cafe down the street for a fraction of the cost.
Craft brewing encompasses coffee making methods focused on tightly controlling all aspects of the process in order to develop complex flavors. Drip pots, like the ubiquitous Mr. Coffee, are convenient, but a survey by the National Coffee Association showed that usage was cut in half between 2014 and 2015 (Link). Despite this, coffee consumption as a whole is expected to rise 9 percent by 2024 (Link ), driven primarily through cafe growth and boutique beans.
Regardless of the brewing method, making coffee is very simple. Beans are picked, roasted, and shipped to the US. The beans are ground to the fineness required by the brewing method, with expresso requiring the finest grind, and French press requiring the coarsest. Nearly boiling water, between 180-185F is introduced to the grounds for some time, before the coffee is extracted and consumed. The final flavor profile depends on the bean, bean freshness, grind size, water temperature, water/bean ratio, brewing temperature, and brewing time. If the coffee is bitter, it may be over extracted, the grind may be too fine, or the water too hot. Watery coffee is a result of under extraction or too much water/beans.
This analysis focuses on the three most popular manual coffee brewing methods to understand their usage, advantages, and shortfalls. Espresso machines and manual espresso makers (Moka Pot, etc) are disregarded. Pod based brewers (Keurig) are also ignored due to their cost, footprint, and waste. Customers select their coffee maker based on their individual preferences and coffee tastes. Is it possible to design one brewer to rule them all?
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The first brewing method is the pour over. A cone is fitted with a paper filter, filled with grounds, and a premeasured amount of water is poured in and filters through. The equipment is very simple, but without tight control on the amount of beans and water, the coffee can easily be too strong or too weak. This method is very popular in coffee shops because of the tight quality control and ease of parallelization, but it is less accessible for home brewers who don't have access to measuring cups and scales for every cup.
Secondly, the French press requires grounds poured into the bottom of a glass or metal carafe, which is then filled with hot water. Minutes later, a wire mesh plunger segregates the grounds to the bottom, allowing the coffee to be decanted off the top. This process creates a robust cup of coffee, but variability in the ground size will create undrinkable sludge. Expensive French presses have tighter fitting metal screens and finer mesh to separate the grounds. The used grounds are hard to remove from the carafe, and the assembly is not dishwasher safe.
A newcomer to manual brewing is the Aeropress. Introduced by an electrical engineer in 2007, the Aeropress has been gaining popularity because of the coffee, short brew time, and ease of use. It consists of a plastic cylinder that sits on top of the coffee cup. A paper filter sits in a cap at the base of the cylinder. Grounds and water are poured in, and a plunger with a rubber shoe gets inserted to the top of the cylinder. The water and coffee is held in the cylinder at a low pressure due to the steam. The slight pressurization aids extraction and reduces brewing time. At the end, the plunger is depressed and the coffee drains into the waiting cup. If a newcomer is handed this equipment, it is unlikely they will be able to produce good coffee since the brewing method is non-obvious. These devices fail when the rubber shoe on the piston degrades.