How to choose beans

The process of brewing a superb espresso beverage starts with proper coffee beans. This is not as simple as getting any old grounds in a can. When considering how to select a bean there are two really important factors to consider: quality, and personal flavor preference. The main focus of the article is to understand the main components of coffee that makes it what it is. Armed with this knowledge you'll be able to make an informed decision to get coffee that suits your palette and make sure you are getting a quality product.

Flavor Terminology

When selecting a coffee you will want to see what kind of flavor notes the coffee is supposed to have. You may find that lower quality coffees do not list a flavor profile on their container. This may be a sign that the coffee is poor quality and should be avoided. Many mass produced coffees do not have the quality control or product consistency to be able to provide this information with certainty. Once you understand what these flavor terms mean you will understand what flavors you like/don't like, so that you know what to avoid when purchasing. Many of the flavor descriptions you'll find on coffee bags are self explanatory, such as chocolaty or smoky, but others are more specific. Listed below is a glossary of common flavor descriptors and what they mean in regards to coffee.

Acidity - This is not a measurement of acidic a coffee is, but is instead more of a measure of how much of a fruity tang or wine-like flavor a coffee has. It can be compared to the pleasant tartness and crispness of a good dry wine.

Aftertaste - The lingering flavor after the the coffee is swallowed. Sometimes the aftertaste of the coffee will be quite different from the initial flavor. A coffee can taste good initially, but then leave an undesirable flavor on the palette.
Aroma - How the coffee smells. Smell has a large effect on the perceived flavor of food. How the ground and brewed coffee smells will affect the taste. You may notice a distinct difference in the aroma of the ground coffee vs. the brewed coffee. Changing the brew process will cause different compounds in the coffee to extract at different rates, which will result in a different aroma profile.
Balance - This is the ratio of different basic flavors such as bitterness, sweetness, acidity, etc. A balanced coffee will have a relatively equal ratio of these flavors, with no one flavor being particularly strong/overpowering.
Bitterness - This is a strong unpleasant taste that usually leaves a lingering aftertaste. It can be described as a medicinal flavor. This is typically a sign over over-extraction.
Body - This is how the coffee feels in the mouth - the density/viscosity on the tongue. A thin bodied coffee will typically have less dissolved solids in it, and feel watery. A full bodied coffee will be creamy and have a thick texture to it. At an extreme, some coffees are described as syrupy, resembling a very thick body like maple syrup.
Brightness - This is sometimes used interchangeably with acidity. More specifically though this refers to a tangy flavor, such as what is found in citrus fruit.
Complexity - This an encompassing term that describes how the different flavors of a coffee or blend work together. Complexity is not inherently a good or bad attribute - it really depends on how well the flavors work together. A coffee can be complex, but have bad flavor, because the different flavor profiles don't work well together. A common reason for coffee blends is the pair different flavor profiles together to build complexity. When done right the coffee will have a fuller/varied flavor experience that is clean tasting.
Cleanliness - This is a measure of how free the coffee is of defects and unpleasantly overpowering flavors. Also a measure of how clearly defined the flavors are - a clean coffee will have flavor notes that can be distinctly picked out when tasted.
Crema - A frothy foam that is a result of the carbon dioxide within an espresso bean being trapped in bubbles as a result of the espresso extraction process. Crema is not a sign of good or bad flavor - bad beans can produce a lot of crema. Crema is a good measure of how fresh a bean is though, because older beans will have outgassed all of their trapped carbon dioxide already.

Earthy/Natural - Coffees described as earthy or natural will tend to have a flavor like soil or dirt. This can be perceived as a negative - especially if it is strong, such as mold/mildew/potato flavors. But like good earthy cheese, an this flavor can provide balance to the overall taste of the bean. This flavor is particularly subjective to the taster, but generally a disproportionately strong earthy aroma is not desirable.
Finish - This refers to specifically the flavors that are perceived in the aftertaste of the coffee.
Floral - Flavor notes that are perceived as being flowery/plant-like, with a perfume-like aroma.
Fruity - A fairly non-descript term that just denotes sweetness/tartness of fruit. Typically a specific fruit or fruits are listed which are more specific.
Smoothness - How easily the flavors of the coffee flow together as it is drank. A smooth coffee will not have sharply pronounced flavors or surprises.
Sourness - A very sharp flavor that causes the palette to clench - leaves a biting sensation like vinegar does.
Sweetness - How sugary a coffee tastes, such as caramel and honey notes.

Robusta vs. Arabica

Robusta and Arabica are two species of the Coffea genus, and comprise most of the modern coffee market. Robustas are usually characterized as lower quality, frequently having defects, and undesirable or harsh flavors. Robustas do produce a lot of crema, so high quality robustas are frequently used in espresso blends. Robustas do not have a lot of varietals.

Arabica on the other hand comes in a large variety of subspecies, commonly referred to as varietals or cultivars. Arabica has such a wide range of cultivars because it has two additional chromosomes. Because of this wide range of subspecies there will be a broad range in quality and flavor. Arabica itself does not indicate higher quality or better flavor than robusta, but there are definitely cultivars of arabica that offer desirable traits and excellent flavor.

There is also a third species of coffee called liberica. This is not a very commonly or widely used coffee bean, and is limited in variety like robusta.

Common Varietals/Cultivars

There are tons of varietals out there. A quick internet search will give you a plethora of information on each varietal. Listed below are a few of the more commonly found varietals.

Bourbon - This varietal is a common standard of good coffee. This varietal is liked by many because of its sweet flavor, well rounded taste and feel, and good complexity.
Catimor - This varietal is typically something to be avoided. These beans commonly have poor flavor, are bitter/medicinal, and low in sweetness and acidity. This is due to a robusta influence in this particular strain. High quality catimors however have a more balanced flavor, and a more herbal flavor in place of the bitter/medicinal flavor.
Caturra/Catuai - These are derivatives of the Bourbon strain. These varietals have high acidity, and a low or medium body.
Ethiopian - These varietals pertain to both a region and cultivars. These varietals are often good quality and feature strong berry flavor notes. Blueberry is often used to describe the flavor notes of this coffee.
Peaberry - This is not a variety, but rather a description given to a coffee bean that is smaller, round, and the two halves of the bean are fused together. They can also formed when one half of the coffee bean seed doesn't grow. These are undesirable when mixed with other beans, but can make good coffee when used in pure peaberry blends. This is because the beans are smaller, so are roasted more quickly and have a tendency to burn.
Typica - The most common and very oldest varietal of coffee. Many other cultivars descend from this one. This bean has had centuries to be refined. Modern varietals of it are known for their clean balanced flavor, which is a direct result of the long time that this varietal has had to be tweaked.

Origin/Growing Altitude

Where and how the coffee is grown will also have an effect on the flavor. Factors such as mineral content of the soil, ambient temperature and humidity, growing altitude, etc. all effect how the coffee plant grows and how the resulting beans taste. This is why single origin coffees can be desirable. Since the plants are grown and sourced in a similar area under similar conditions there will be less deviation in their flavor, resulting in higher quality and better consistency.

One of the more important factors that you will see specifically listed on coffee containers is the growing altitude. The higher growing altitude typically imparts more desireable flavor traits onto the coffee. Because of the better flavor and more difficult growing process, higher altitude coffees will be more expensive.

Processing

Processing refers to what is done after picking the coffee off of the plant before hulling the cherry of the coffee bean. There are three commonly used processes, which each have their own variations, in addition to a plethora of other less commonly used processes. How the coffee is processed again has a large effect on how the resulting bean will taste. An improperly processed bean can have an unpleasant earthy flavor, mould/mildew flavors from improper fermentation, or have poor flavor consistency.

Dry/Natural Processing

This is a simple process of letting the coffee cherry simply dry out from the ambient air. Once the bean has reached the appropriate moisture content the flesh of the bean is removed. This process is more common in arid climates, or where equipment is available that can strictly control the ambient humidity. Some beans are left on the tree for drying. Dry processed beans have a larger tendency towards bean defects because it is not as easy to sort out unripe beans.

Wet Processing

This process involves using water to remove the outer layer of the coffee cherry to access the bean. The coffee cherry is composed of the bean in the center, a thin layer surrounding the bean called the silverskin, which is surrounded by a shell called the parchment. This is suspended in a sugary layer call the mucilage. Lastly there is the outer skin. During wet process this outer layer is removed, and then the beans are soaked in water for a period of time, which can last up to a week. Since the outer layer has been removed the mucilage is directly exposed to the water, which begins to dissolve the sugars of the mucilage. This portion of the process is referred to as fermentation. The longer a bean is fermented the more sour it will taste. This can help bring out fruitier and more acidic flavor notes in a bean. If the fermentation is allowed to go too long though the bean can become overly sour, or take on mold/mildew flavor notes. After the coffee is finished fermenting the bean is thoroughly washed to remove the remaining mucilage. This process has an advantage over the dry process because unripe beans can be more easily separated out.

Pulped/Honey Processing

This process is similar to the wet process, except that the beans are not fermented at all. After the outer layer is hulled the beans are immediately washed and then dried. Depending on how much of the mucilage is remaining after the washing will effect how sweet and acidic the bean is. Again, this type of process requires a dry climate or equipment that controls the ambient humidity. Because the mucilage is left in place the beans have to be dried fairly rapidly; the sugars from the mucilage promote rotting/bacteria growth if the bean is not dried quickly enough. This process is desirable because it strikes a balance between the flavors produced by dry and wet processing.

Roast

Roasting changes the flavor of the beans by heating the beans. This causes some of the chemical compounds to denature, some of them to burn off or be removed by steam, and increases the carbon content of the bean. How much of the original flavor of the coffee is left depends on how much the bean is roasted. Because of how much the heating can change the flavor of the coffee it is an important factor to consider.

Light Roast

Very lightly roasted coffee can taste grassy, like sweet hay. Finding these flavors in the brewed coffee may indicate that the bean was under-roasted. Going up from there is light roasted coffee. This is coffee that has been roasted to around the point of the first crack. The first crack is when the beans start to pop in the roaster. Light roasts range generally from just before, during, or slightly after the first crack. When trying to emphasize the natural flavors of a coffee a light roast is typically picked. The flavor compounds in the bean have not been greatly affected at this point.

Medium Roast

Moving on from there are medium and medium dark roasts. These roasts fall in between the first and second crack. At this point the beans will start to take on more carbon content, the flavor compounds will begin to be roasted out of the bean through steam, or burned off from oils that are pushed to the surface of the bean. For the most part though the flavors will still be fairly intact, but will start to be masked by the caramelization of the sugars in the bean.

Dark Roast

Dark roasts modify the flavor content of the bean the most. Dark roasts are typically near or after the second crack, where the beans again begin to pop. At this point the sugars have almost completely caramelized, turning into carbon. This roasts will have strong bitter, smokey, and burned notes. These beans can be problematic in burr grinders and super-automatic machines, because they have such high surface oil content that they clog the grinding mechanisms of these machines. Dark roasts are frequently used for beans with defects, or poor quality beans. Since this roasting process removes most of the natural flavor of the beans, undesired flavors are easily masked. Caution should be used when purchasing darkly roasted beans - make sure you are getting a quality product.

Caffeine Content By Roast

There is a wide range of subcategories to these broader roasting categories. Doing an internet search of a particular roast type will yield more specific information regarding roasting temperature and its effect on the bean. Another factor affected by roasting is the caffeine content. Darker roasted beans will be less dense, resulting in a different caffeine content per volume. If measured by weight, however, light and dark roast beans will have the same caffeine content gram for gram. It is a common misconception that light roasts contain more caffeine - it all depends on how the coffee is measured for brewing.

Blends

Blends are simply the combination of two or more coffee beans. Different beans are selected to pair together because of similar or complimenting bean characteristics. Blending coffees can be helpful in creating balance if one of the beans has a flavor that is too forward. Blending can also help create complexity. For espresso in particular blending is common - a small amount of a robusta bean is frequently added in blends marketed for espresso to create a richer crema content.

Caffeine Content

Several of the previously described factors affect the resulting caffeine content of the bean. The variety of bean, how it is roasted, and how it is prepared has a large effect on the resulting caffeine content.

Decaffeination is a process in which beans are stripped of their caffeine content through a solvent. The caffeine is not completely removed. Decaffeinated beans can contain 2-3% of their original caffeine content. Modern decaffeination has seen large improvements, and up to 99.9% of the caffeine content can be removed; coffee is often required to have this much of the caffeine content removed in order to be labeled decaf depending on where it is being sold. The process of decaffeination does have an effect on the resulting flavor of the coffee, usually impacting it negatively. Beans that are decaffeinated using the Swiss water process are usually more desirable in terms of flavor, because this process is less disruptive to the beans natural flavor content.

There are three common techniques for removing the caffeine content. This article here describes the processed in further detail.

Flavors

Coffee beans are flavored by applying chemicals, flavored oils or syrups, or powder coatings shortly after the bean has been roasted. These impart a flavor to the coffee that would not naturally be there. This is a point of controversy, especially for the experienced coffee drinker. There are some important things to consider before purchasing a flavored coffee bean. The biggest precaution is to make sure what you are getting is a high quality bean. In many cases flavorings are used to mask bean defects, or make an old stale bean drinkable.

A properly flavored bean will use a fresh bean that is free of defects and high in quality. The bean the flavor is being applied to should have natural flavor notes that complement or enhance the flavor being added to it. The natural aroma of the coffee should still be able to come through the added flavor, so that is is not completely masked.

High quality coffee beans will have natural flavor notes, usually listed on the container they are sold in. By selecting the right bean you can get coffee that is fruity, chocolaty, etc. without any additional flavorings being added.

Preground Vs. Whole Bean

Coffees are sold as whole bean or preground. Whenever possible it will be better to purchase coffee that is sold as whole bean. If you have the proper equipment to grind the coffee for the desired brewing method this will always be the better option. Purchasing whole beans is better for several reasons. The most important factor is that coffee beans are like any other perishable food item - the quality of the bean goes down as it ages. By keeping the bean whole the rate of decay is much slower.

The reason for this is that a whole bean has much less exposed surface area. Like apples or potatoes, when a bean is cut/ground up the newly exposed surfaces will oxidize rapidly. Coffee beans are already brown, so it's hard to detect, but those grinds are absorbing oxygen and degrading in flavor, just like an apple that is cut and left out turns brown and tastes unpleasant. Keeping the bean whole reduces the overall surface area that is exposed to oxygen, slowing down the rate of decay.

Another argument against preground coffee is that the coffee is already ground for you. You have no control over the grind size, so the coffee may not be ground appropriately for the brewing equipment being used. Correct grind size is essential for good tasting coffee that is extracted at the correct rate. This is especially important for espresso extraction where even small changes in grind size will have a large effect on the rate of flow and resulting flavor of the coffee. When selecting a pre-ground coffee make sure that it is ground appropriately for the brew method it is being used for.

When purchasing either whole bean or preground coffee it is best to make sure it is packaged properly as well. Proper packaging keeps the beans/grounds fresh. After coffee is roasted there are gases that are released over time. Properly packaged coffee should have a one way valve installed in the packaging so that the coffee can properly outgas, helping the coffee stay fresher for longer.

"Espresso" Beans

One of the largest misconceptions in the coffee brewing world is that espresso is made from an entirely different bean or coffee varietal than other coffee brewing methods. This is not in any way true. A wide range of coffee blends, roasts, and bean varietals can be labelled as "espresso." This is simply being used as a marketing term. Espresso beans are coffee beans. When a package is labelled as "espresso" then that particular company is simply suggesting that that particular roast/blend/variety/etc. is what they suggest be used for the espresso brewing process. You can have two different coffee beans on complete opposite ends of the spectrum that are both labelled as "espresso."

Espresso is a brewing method for coffee beans. Espresso is a process in which coffee is brewed by applying high heat and large amounts of pressure to finely ground coffee beans. This process can be used with any coffee bean. Some coffees will be better suited for espresso extractions than other, but this is highly subjective as it will depend on many variable, the most influential being personal flavor preference.

For pre-ground coffees in particular the label "espresso" can be of particular importance though. In addition to meaning that the particular producer of that bean suggesting that the bean used for espresso, this also means that the coffee has been ground in the espresso range. This would make it unsuitable for other brewing methods as the coffee would not extract at the proper rate.

Milk Drinks

If you plan on using the coffee for milk based drinks such as lattes it is important to select a bean that will work well for this purpose. Beans with weaker or more subtle flavor profiles may not work because the milk may wash out the flavor of the coffee. Coffees with bolder more pronounced flavors can be more desirable, because the natural flavor of the coffee will come through the milk. It may also be more desirable to have a medium or full bodied. A light bodied coffee can make milk based drinks like lattes end up tasting watery. Fuller bodied coffees will contribute to the richness that is usually desired in a latte.