Most coffees brew well as drip or french press with little effort, but that is not the case with espresso. The considerations for espresso are freshness, origin, processing method, and roast profile. If you do not have the right coffee, you cannot make good espresso, no matter how good your equipment.
Freshness
Coffee older than 3 weeks after roast usually does not make good espresso. After coffee is roasted, oxygen over time makes the coffee stale and volatile components evaporate from the beans. The result is that the ground coffee does not offer enough resistance to the brew water under pressure, no matter how fine you grind it. The resulting brew does not have proper body and does not taste good. I will discuss roast profiles later, but darker roasts get stale faster than lighter roasts.
Your best bet is to buy coffee from a local roaster in small quantities (12-16 oz) as you need it. You should only buy coffee with a roast date on it, and keep in mind your window to make espresso is usually less than 3 weeks after the roast date. You can also buy coffee online that is roasted to order, so you know it is fresh.
Bulk coffee at grocery stores is not properly stored (it should be airtight), and usually does not have a roast date, so you should avoid it. Most coffees at grocery stores do not have a roast date and it can be months old; it will not make good espresso either. Some mainstream roasters (like Peets or The Coffee Bean) put the roast date on their beans, but it is difficult to get a bag at a store that is less than 2 weeks old. Larger stores like Costco have some of these coffees with roast dates on it, and if your store has high inventory turnover, you might be able to find recently roasted coffees there. However, these brands are usually at the dark end of the spectrum, which may or may not be your preference (and it will also go stale faster).
Industrial packaging can keep coffee fresh for a little longer, but once the coffee is opened, it catches up to its age quickly. Meaning if you make an espresso as soon as you open the bag, it may work well, but the next day the coffee will not extract correctly.
Other than buying fresh roasted coffee often, your two other options are buying in bulk and freezing it in small airtight containers, or roasting your own coffee. I discuss freezing coffee beans in the next section, and I will cover roasting coffee in the future in a separate page.
Degasing
There is such a thing as too fresh coffee for espresso. Coffee releases a lot of CO2 for a few hours after roasting and should rest at least 48 hours , or even longer for lighter roasts. Brewing sooner than that results in espresso that does not taste right, with sour and funky notes, and way too much crema.
Keeping coffee fresh
Coffee beans left exposed to air and light become stale very quickly. You should store coffee beans either in an airtight bag (many roasters package their coffee in those) or in an an airtight container that you seal each time you use it and put in a cabinet away from light and heat.
My favorite way of storing beans for espresso are the ceramic Airscape containers. These containers have a lid with a valve that you can push all the way down and push out most of the air and then seal the contents air tight, no matter how little or how much coffee you have. They also look great. Two of these containers can store a bag of 12-16 oz of beans, with the benefit that the second half of the bag will stay always sealed on the second container while you go through the beans in the first one. An alternative is to split the bag in Mason jars so several of them stay closed while you go through the beans in one of them.
I do not like to leave beans on the hopper of the grinder overnight. I discuss more on workflow and how it relates to keeping coffee fresh in other pages.
Freezing coffee beans
Freezing coffee is useful to save money on shipping charges by ordering a large bag from a roaster online, to have several varieties of beans in your house without them going stale, or to avoid running out of coffee if you don’t want to leave the house. If done properly, freezing coffee beans does keep them fresh for weeks or months. However, I find it a hassle to do this and I do not freeze coffee beans often.
To freeze beans, split a large bag of freshly roasted coffee into Mason jars and close them air tight. Write the roast date and type of coffee on the lid and put them in the freezer. The night before you want to use them, take them out of the freezer but do not open the lid. Let the beans come to room temperature overnight before you open them. This prevents condensation on the beans. After you open a jar, use what you need and store the rest airtight, in the jar or preferably in an Airscape container.
Origin
Most coffees used for espresso are from South or Central America. These coffees often have flavor notes of chocolate and nut, with low to medium crisp acidity. Coffees from Brazil offer great body and mouthfeel for espresso and also chocolate and nut tones, however, they are low on acidity. Brazil is one of my favorite origins for espresso, especially for milk drinks, and these coffees are also easy to brew as espresso consistently. The lack of acidity, which is a personal preference, makes them less desirable for many people though. I am okay with little to no acidity in my espresso and prefer coffees that have more acidity for drip coffee. Coffees from Guatemala make great espresso with less crema and moderate crisp acidity, as do those from Colombia.
Coffees from Indonesia add more earthy tones, with some people liking them and some hating them. African coffees, especially from Ethiopia, add more berry-like fruity notes to the taste of espresso but some can be too acidic (like Kenya).
In most cases blends make for tastier and more balanced espressos and milk drinks than single origin coffees. This is because espresso brewing really highlights any salient characteristics of any coffee, and also different components of the blend can contribute each of their good attributes in different proportions to make a a great drink along all dimensions (body, flavor notes, acidity, and so on). Single origin coffees can also be more difficult to brew correctly as espresso, especially if they are roasted very light. However, you should try single origins as espressos every now and then, to learn more about which origins have the flavor characteristics you prefer.
There is much more you can learn about coffee origins. Also not all farms produce coffee of the same quality, so the specific producer matters. This is why some premium roasters display the specific farm name on some of their offerings.
You do not need to become an expert to find and enjoy coffees you like.
Processing method
Coffee is kind of like a fruit, like a cherry, and the bean is its seed. Once coffee is harvested, the pulp of the fruit needs to be removed, with only the seed left behind for later roasting and brewing. There are two main processing methods: dry and wet. The specific process used usually depends on the location, climate, and infrastructure available to farmers where the each coffee is grown. Each process also affects the flavor characteristics of the resulting coffee in different ways.
Dry processed coffees are left to dry in raised beds by the sun. When the fruit pulp is dried, it is then easier to separate the seeds from the rest of the fruit. Dry processed coffees usually have less acidity and sometimes more sweetness. They are also usually denser and tend to have better crema and body when brewed as espresso.
Wet processed coffees use water to soak the coffee fruit and separate the seed from the pulp. Wet processing is usually a bit more complex and used in regions that do not have as much sun or that have better infrastructure available to farmers. These coffees retain more delicate flavors and a crisper tea-like acidity compared to dry processed coffees.
As a general rule in espresso dry processed coffees have better body and crema, a bit more sweetness, lower acidity, and are easier to brew correctly. Wet processed coffees have more subtle flavors and more pleasant acidity. Espresso blends often include components that have been processed using both of these methods, with at least half of the blend dry processed.
Roast profile
Different roasters mean different things when they talk about medium or dark roasts, so what one roaster calls medium roast another might call very dark roast. The range of roasts that are good for espresso is narrower than other brew methods like drip: a roast good for espresso is darker than traditional medium roasts for drip coffee, but also lighter than Starbucks. Beans look typically medium to dark brown (but not light brown nor closer to black), and may have no oil on them or just a small amount.
Roasts that are too light are prone to channeling (the water under pressure blowing a hole on the coffee during brewing) and often result in espresso shots that are very sour. This is because the grounds of a light roast do not stick together very well, so it is hard for them to provide enough resistance to coffee grounds. Exceptional roasters are able to create light roasts that have been developed during roasting so they do make good espresso, but those are few and far in between. In those cases you can taste more of the origin characteristics of the coffee, and less of the notes imparted by the roasting process. These are usually better for straight shots as these more delicate flavor notes get often lost or too diluted in milk drinks.
With light roasts, the margin for error is very small, both in technique and in the quality of the grinder and machine. This is why in general I do not recommend lighter roasts for home espresso. It is difficult to achieve drinks that taste good consistently without lots of experimentation and top of the line equipment (which in general is a waste of money for the home where only a few espresso drinks are made per day).
A lot of coffee is marketed as espresso roast that is just too dark to make a good drink. It will usually have names like italian roast or espresso roast or french roast. These are in general coffees to avoid for espresso. These roasts are usually too dark and oily; they go stale very quickly, and they leave too much oil residue on your grinder and equipment. In the event that you can make a good drink out of them, it is roast flavors that dominate, with no interesting origin flavor characteristics at all. These very dark roasts also go stale very quickly. You may get some chocolate notes on day 2 or 3 after roast, but by day 6 the flavors change to rancid bitterness. You may wonder if somebody just switched your coffee with a different one while you slept. It really changes that much.
Somewhere in the middle of these two extremes is what you want for home espresso. Reputable roasters (I discuss recommendations in other pages) will be able to advise you or designate one of their blends specifically for espresso. Within this range, lighter roasts show more origin flavors and sweetness but have a lighter body, while darker roasts have more nut and chocolate tones and thicker body, often better suited for milk drinks. Lighter roasts need to rest longer after roast (up to 7 days) and will have a longer window to make good espresso, while darker roast can rest as little as 2 to 3 days and will have a shorter window of time to make good espresso (maybe closer to 2 weeks than 3 weeks) before the taste changes too much or are difficult to extract correctly.
Conclusion
The best strategy is to try espresso drinks at local cafes and find the roasts and blends ones you like the most to get those beans for home. For online roasters, you can try a bag from a few of them, if no local roasters are of your liking. In all cases, keep your coffee airtight inside a cabinet away from heat and light. Take some time to find three or four coffees you really like so you can have some variety over the weeks.
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Great Espresso at Home 