In my explanation of why Muggswigz coffee has grounds at the bottom of the cup, I am describing some different brewing methods. Last week I wrote about three methods of brewing coffee; Middle Eastern (aka. Turkish or Greek), concentrate brewing, and percolating. In this issue, I'm going to write about vacuum brewing, drip brewing, and French press (aka. plunger press) brewing.
Vacuum brewing uses an elegant looking device that consists of two glass globes that fit together with an air-tight seal. Either in one of the globes, or between the globes, is a filter to separate the grounds from the liquor. Ground coffee is placed in the upper globe, often on top of the filter, and enough water to brew the grounds is placed in the lower globe. The globes are then fitted together and the lower globe with the water is heated. The water in the lower globe begins to heat to a boil and as this causes the pressure in the lower globe to increase it forces the water up a tube connecting the globes and into the upper globe containing the grounds. Once all the water has made this air pressure induced trip, the apparatus is taken off the heat source. This allows the lower globe to cool down back to room temperature, decreasing the pressure in the lower globe and thus sucking the brewed coffee back down (through the filter) into the lower globe. The coffee is then poured out of the lower container and enjoyed. Well, perhaps not always enjoyed. Because while the vacuum brewer is a great visual, scientific, and romantic experience, it does not always produce the best cup. A great cup of coffee can be achieved with the vacuum brewer, but it has its downfalls. Firstly, the coffee is being extracted by water around 212F, while it should be extracted between 195F-205F. Secondly, their is very limited control over the extraction time (the time grounds are in contact with water). Some swear by this method and it is growing in popularity. Perhaps I need more training in the technique, but I've never had very much luck with vacuum brewing. If you want to try vacuum brewed coffee, I think you can find the brewers at more up-to-date houseware stores, and I think they my sell the bodum version at Starbucks, or if you ask nicely I'll loan you one of mine for a test run.
Autodrip! This is the most popular way to brew in the US. Drip brewing is simply pouring hot water over grounds in a filter and letting the brew drip out the bottom. Drip brewing is a very good way to brew and can give an excellent cup if the correct equipment is used. A primary issue with autodrip machines is that they don't brew at the right temperature! I have read that Bunn is one of the few companies who's machines are calibrated to extract at the right temperature. If one has a good autodrip machine or one decides to heat and pour the water themselves, the next issue to surmount is the filter. Paper filters can impart a taste on the coffee and also do not allow many of the coffee oils and organic compounds through. A good gold-plated reusable filter (we do carry some) is a great option for drip brewing. Provided you clean and rinse it well after each use, it will not impart a taste on the coffee, and they don't trap as much of the coffee's essence as a paper filter. Another slight drawback is that drip brewing, in general, does not give the operator much control over extraction time.
French-press brewing gives the operator complete control. While it may be more labor-intensive then autodrip, the brewing variables can be easily and directly controlled. Coarsely ground coffee is placed in the glass carafe, then water at the desired temperature is poured over the grounds and the top is placed on. When brewing is complete, the plunger (a mesh filter on a stick) is pressed down, pressing the grounds to the bottom and leaving the coffee liquor on top to be poured off. The filter is not as tight as a paper filter and because of the larger pores, a coarser grind is required so the grounds are filtered out, and the plunger does not become almost impossible to press down. The mesh of the filter allows the coffee oils and all those delicious dissolved and undissolved solids through without a problem. Also, because a coarser grind is required, a longer steep time is required (because of the decreased surface area to volume ratio). A brew time between 3 to 6 minutes is common for French-pressing. This prolonged, direct contact of the grounds with the water allows for a more complete, more controllable, and even extraction. Unfortunately, even with the highest quality burr coffee grinder or mill, a coarse grind will still result in some very small coffee grounds. These grounds are not filtered by the French-press filter and thus end up in the cup. A cup of French-pressed coffee with be noticeably fuller, with much more body, and often with more flavor, it will often also have the tell-tale sediment at the bottom of the cup.