Common Methods of Brewing Coffee
Espresso Coffee Makers
The word espresso means three things. It describes the beverage or infusion, the blend to make espresso, and the method used to make espresso. It is the latter that we are concerned with. Don't confuse the method with the beverage. The espresso machine was originally invented to make coffee, not "espresso". The term espresso in reference to the beverage came into use later. To the Italians espresso is coffee. The espresso method of brewing is the ultimate method of extraction. It falls into the percolation category, with a twist. A very fine grind can be used, because the hot water is forced very rapidly around and through the aggregate under great pressure (about nine to ten times normal atmospheric pressure). The water actually being forced through the coffee particles is what puts the espresso method in the percolation category. This results in the maximum amount of desirable solubles being extracted, but because the process is so fast, not all of the bitter compounds have time to dissolve. Less of the caffeine is dissolved, when compared to other brewing methods. What's really significant about the espresso method is that the hot water under pressure is able to emulsify about ten percent more of the oils (fats) in the aggregate than any other method. It is the oils that give coffee it's body and smoothness, and greatly enhance the flavor. The infusion produced by the espresso method is more viscous (thick) and has a lower surface tension. Lower surface tension enhances the ability of the liquid to coat the papilla where the taste buds are located, thereby enhancing your ability to sense flavor. The lower surface tension also enables the tiny oil droplets to penetrate the pores of the papilla and slowly release the aromatic substances that have bound to the oils. This accounts for the noticeable after taste of coffee brewed in an espresso machine. The additional oils also inhibit the sensory receptor cells from sensing bitterness. Don't be confused into the notion that espresso coffee is something different than regular coffee. Espresso coffee is regular coffee. The beans for traditional espresso coffee have been specially blended and roasted longer to produce a unique effect. Espresso coffee is brewed, and consumed at very concentrated brewing and drinking ratios. In short, by using the espresso method properly you get more of what you want and less of what you don't want, and that simply translates into the best coffee imaginable. The beauty of the espresso method is that once the proper grind has been determined, and the desired proportion of coffee to water has been determined, the rest is handled by the espresso maker. It is the simplest method, requires less time on your part, requires the least amount of cleanup effort, and produces perfect results every single time. In fact good automatic espresso makers are as easy as pushing one button. Of course there is a hefty price to be paid for such convenience. But, we think the price is well justified if you want the very best coffee.
The key to understand in this method, is not to use too much water in the espresso maker. Let's say you wanted to make a cup of coffee that was equivalent to the standard brewing ratio rather than espresso strength. You would generally use 6.8 grams of coffee, and 1.25 fluid ounces of water to brew the coffee. It is very important that the correct balance of grind size and degree of tamping of the ground coffee is achieved. The water should be forced through the aggregate in 15 to 25 seconds. After the coffee is brewed, you add just under half a cup of water (3.9 fluid ounces) to the cup. If you ran all of the water through the ground coffee, you would severely over-extract the coffee, and it would not taste good at all. Automatic espresso coffee makers are the most convenient method of making coffee in existence, but there are important considerations to be aware of. Only the short coffee (espresso), or double short coffee (double espresso) options should be used. The regular coffee or tall (long) coffee options should not be used. They use the same portion of ground coffee as the short coffee, but force more water through the aggregate. This results in over-extraction. As mentioned before, you should add the necessary hot water after the extraction process. The other drawback to the automatic machines is that there is always a small amount of ground coffee left in the machine from the last cup that you make. This ground coffee will go stale in a matter of hours, and then will be included in the preparation of the first cup the next day. Unless your machine provides an effective way of purging all unwanted ground coffee, the first cup made should be disposed of. Convenience has yet another price.
Brew & Filter
The brew and filter method is the classic coffee connoisseur's method of brewing coffee, and is in the maceration category. The beans are ground, placed in a container, hot water is added, and the container is covered. Allow the infusion to steep for about 3 to 4 minutes. It is best to steep closer to 3 minutes rather than 4 as it is very easy to over-extract using this method. During the steeping process, stir the infusion at least three times, always replacing the cover. After steeping, the infusion is poured off into a cup through a nonabsorbent filter. The best filter choice currently is a gold filter. Under no circumstances should a paper filter be used. A paper filter will absorb some of the essential oils in the infusion, and since less oils have been emulsified with this method, as opposed to the espresso method, it's essential that you don't lose any of what you do get. This method, and all other methods, require a much longer exposure time than the espresso method, which means the aggregate must be coarser. If the coffee was ground as fine as it is for espresso, then too many of the undesirable compounds would be extracted, or if the exposure time were shortened, much of the desired compounds would not be extracted. The problem with the coarser grind is that, due to the larger particle size, the longer brewing time is necessary to extract the desirable compounds nearer the center of the particles. Obviously, the compounds near the surface of the particles get too much exposure to the hot water, allowing extraction of the undesirable compounds. A compromise must be struck, and this is done by trial and error to each individual's taste. Once you have determined your proper brewing time for any particular strain of coffee, stick with it. The brew and filter method is preferred by many people over the espresso method, because the sensation of taste is not as "heavy", and the acidity and "brighter notes" can be more apparent. You might choose the espresso method for some coffees and the brew and filter method for others.
Plunger, French Press or European Press
The plunger method (maceration category) is where the ground coffee is placed in a cylindrical container and hot water is added. A disc (with a rod attached in the center), which is same diameter as the cylinder, is placed over the water and ground coffee. The disc has many very small holes in it, or large hole covered by a fine mesh screen. There is a physical limit to how small these holes can be necessitating a fairly course grind. After about four minutes of steeping, the disc is pressed down through the infusion forcing the coffee grounds to the bottom, and allowing the infusion to be poured off. This method produces excellent results, but you generally have to use twice as much ground coffee because the grind has to be so much coarser. You can use a finer grind if you don't mind the resulting sediment n your cup. When using a finer grind, it's best to use a total steeping time closer to 3 minutes, and press the disc down slowly, starting at about 2 and a half minutes of steeping. With a finer grind, pour the coffee slowly, and leave a little in the press. This will greatly reduce the sediment in your cup.
The drip method is the least desirable of the acceptable methods, and falls into the percolation category. We are not, by any means, saying that you can't produce a thoroughly enjoyable cup of coffee using the drip method, but simply that it won't be as good as it can be. The drip brewer must be designed perfectly. The opening that allows the infusion through to the cup must be just the right size to keep the hot water in contact with the aggregate for the right amount of time, between 3 1/2 to 4 minutes. Over 4 minutes and you'll be over-extracting. The longer it goes, the worse it gets. There are a number of problems inherent with the drip method. First, some of the water goes through quickly, resulting in under-extraction, and the infusion that drips through last is over-extracted. The drip method relies on gravity to move the water through the aggregate, thwarting optimal extraction. The other problem with drip brewers is that the extraction will vary depending on how much coffee you're making. If you're brewing a full pot, the higher level of water in the basket creates more head pressure causing the water to pass through more quickly, and the initial infusion is even less extracted than when you're brewing just one cup. Look at it this way -- If it takes longer to brew a pot of coffee than it does to brew one cup, then something has to be wrong. There is an optimal amount of time for aggregate to be exposed to the hot water, no matter what amount of coffee you're brewing. Cone filter designs do a better job than flat filter designs. If the design of the drip brewer does not allow for adjustment of the extraction time, then you're not going to be able to make good coffee, except for one amount. If there is a drip brewer that provides a means for adjusting the extraction time, we would like to know about it! An inferior drip brewer can ruin perfectly good coffee to the point that even an expert coffee taster couldn't identify the coffee. Optimal extraction time is precisely why coffee connoisseurs prefer the preceding methods. If you are going to consider a drip brewer, you should pay close attention to the extraction time, and stick with small capacity designs. Above all, make sure it employs a gold filter ... never a paper or fiber filter. The drip method requires a lot of experimentation. One of the most critical factors to keep in mind is that different coffees will produce different extraction rates. The darker coffee is roasted, the longer the extraction time, all other factors being equal. Decaf will really slow the passage of gravity drawn water. The bottom line is that you have to make what ever adjustments are necessary for the coffee you're brewing in a drip brewer. There is no simple solution. Using our Grind Size Calibration Chart will provide a good starting point for determining how to grind your coffee.
The percolator method deserves little attention, in light of the preceding discussion. Constantly recirculating boiling water through ground coffee will obviously result in Over-extraction. Simply don't use it.