There are many factors that go into a good cup of coffee, from where the bean was grown, how it was processed, when and how it was roasted, how and how long it was stored, when and how it was ground, and finally, how it was brewed. We’ll cover each of these in a little more detail.
The best coffees in the world are what are called “high-grown” coffees, meaning they are grown at elevations greater than 2,000 feet, and usually between 4,000 and 6,000. These coffees grow from Arabica trees, which can not tolerate extremes of temperatures, and thus grow best in certain well-watered, mountainous regions of the tropics. The next lower grade of coffee is grown at lower elevations, still from the Arabica tree, but are processed carelessly, and the end product is far inferior to the high-grown coffees. These coffees are misleadingly called “Brazils”. The lowest grade of coffees grow from another species of coffee tree, commonly called “Robusta”. It is heartier than Coffea arabica, can grow at lower altitudes, and it resists disease. However, it lacks the aroma and flavor of the best Arabicas, and has 30-40% more caffeine.
Coffee beans are processed using one of two basic methods, wet processing or dry processing. Wet processing entails soaking the fruit of the coffee tree in water, and allowing the pulp to separate from the seed that way. The other method involves letting the fruit dry in the open air, and then removing the dried pulp. Depending on the care taken during processing, either method can produce fine quality coffees, although dry processing tends to provide less consistency and more earthy flavors to the coffee.
Coffee can be roasted using a variety of contraptions, with a simple air powered popcorn popper being sufficient to do the trick (most commercial roasters are obviously more sophisticated!). The basic concept is to take the green coffee bean, heat it (i.e. cook it) to the desired level of darkness, and then cool rapidly enough to stop further cooking. The temperature used for roasting, as well as the length of roasting, both play a large part in the final flavor, as a dark roast roasted slowly tastes different than an equivalent dark roast roasted more quickly. The biggest factor in roasting, all things being equal, is that within 1 week after the beans have been roasted the beans begin to lose their flavor. Typically, however, the beans are still good for 3-4 weeks after roasting, provided that proper care is taken. Proper care involves storing the beans in a dry, dark environment. Refrigerators are not a good place for storage (introduces moisture), but freezing is a good way to prolong the shelf life of beans that will not be used immediately.
In the real world, the fineness or coarseness of the grind is determined, at least in part, by what kind of coffee maker and what kind of filter are being used. Ideally, however, the coffee beans should be ground to a fine powder. The finer the grind the greater the surface area of the coffee bean that is exposed to water, and the more of the oils and colloids can be extracted from the bean. The only kind of coffee that requires finer grinding than espresso is Turkish coffee.
Types of Grinders:
1. Blade Grinder – Although inexpensive and fast, these grinders do not give a consistent grind, either in the same batch, or from batch to batch.
2. Burr Grinders – These are more expensive, but also provide a better quality grind. Burr grinders can be broken down into regular burr grinders and conical burr grinders, but the difference between the two is not significant for our purposes.
There are thousands of patents on coffee brewing devices, but few are revolutionary. The basic types of coffee brewers include percolators, drip brewers, automatic drip brewers and French Press brewers. There are several other types as well, but those are rarely encountered and thus not pertinent at this point. The brewer used at Scraps is an automatic drip brewer. The main points here are the temperature of the water used for brewing, again the grind of the beans, and also the type of filter used. Paper filters produce a cleaner taste, and is what most American pallets are accustomed to. Permanent filters (i.e. ones that get reused) have much larger pores (thus requiring a more coarse grind), but allow colloids and other particles through, giving greater flavor but more body to the coffee. Whether paper filters or permanent filters are better depends on the individual. The temperature of the water is also important, and can range from room temperature (which takes a long time to brew) to just under boiling. If the water is too hot it damages the oils inside the beans.
So, we see that many factors go into making a good cup of coffee. For the average consumer, fresh roasted beans ground at home and brewed with a brewer from a reputable manufacturer should produce a good cup. You may need to experiment with the amount of grounds used per cup of coffee to find the desired strength. For those that are less picky, beans may be ground at the coffee shop, and then kept in the freezer to preserve freshness as much as possible. Either way, whether buying whole bean coffee or grounds, coffee that will not be used immediately should be kept in the freezer, where temperature and light exposure are both controlled.