Espresso Brewing Guide
Pulling the perfect shot is an elusive, but rewarding art determined by a few key techniques. Espresso at its simplest is a coffee brewing method which utilizes heat and high pressure to extract flavor from ground coffee beans. While this definition may sound straightforward the actual practice of brewing a great espresso involves balancing different variables to produce the best results. Brewing a great shot of espresso is similar to a controlled experiment, where you understand the effect of each variable. This is why espresso brewing is commonly referred to as both an art and a science.
Selecting the right bean for the right beverage is the first step to pulling a great shot, and often overlooked. For simplicity, let’s break down the innumerable varieties of coffee into three categories: light, medium, and dark roasts. Since espresso extraction is a much more concentrated brewing method than other coffee brewing methods, the quality of the bean is very important. Espresso concentrates and amplifies the inherent flavors of the beans. Simply put, if the beans being used are poor quality, then the resulting extraction will also be poor quality. Just like any other form of cooking, using quality ingredients is important for getting the best results. When selecting a bean you will want to anticipate what flavor profile you would like and what equipment you will be brewing on. Certain espresso machines (super automatics) and grinders are not compatible with oily beans for example. Using fresh beans, which were only opened within the last two weeks is important. Typically we suggest a light/medium roast that is dry, fresh, and roasted dry with no excess oils. These dark roasted coffees also tend to be roasted such so as to hide imperfections in the beans themselves. They’re best avoided. Just as well, you should avoid using flavored beans with your equipment. The sugars can plug up parts and leave behind a flavor/odor in your equipment that may be undesirable.
Grind Setting & Dose
The grind and dose size determine your coffee’s extraction rate. Your dose is going to depend on whether you are making a single, double, or triple shot, as well as the type of brewing equipment you are working with.
The suggested dose for a doubleshot is about 16-20 grams of coffee, depending on the basket and your flavor preference. If your machine comes equipped with a brew pressure gauge and you find your shot time to be perfect, but your coffee is weak, you may need to dose more coffee.
Grind size is how the timing of the shot is controlled. For best results you will want a grinder that has a high degree of consistency. A more uniform particle size will cause the water to distribute evenly across the entire coffee puck. There is even resistance across the entire coffee puck, which forces the water to flow through the coffee evenly and prevent channeling. When making espresso, the ideal grind size to start with will be a little finer than granulated sugar. You want a shot of about 2.5 oz in 25-30 seconds. If it comes out to quickly, adjust for a finer grind. Too slowly, and you can back out to a coarser setting.
When picking equipment, remember that a higher quality espresso machine will require a higher quality grinder. A best-in-class espresso machine won’t pull amazing shots if the grinder is lower quality and the grind is imperfect. Burr grinders will be best for the consistent grind espresso needs. Beyond that, burr size and material, motor power and RPM, doser or doserless, and other factors will need to be considered.
Tamping is integral to making fine espresso. The purpose of tamping your grounds in the portafilter is to create a uniform surface through which brew water can flow evenly. When your grounds are in the portafilter basket, lightly shake the portafilter from side-to-side to evenly distribute the grounds, and level off by brushing your finger across the surface. When tamping, you want to apply a strong but measured amount of pressure to the grounds on a level surface for an even tamp. A good starting point would be about 30 lbs of pressure.
Depending on your shot times, you will want to adjust your grind size to make adjustments to get ideal extraction times. Keep your tamp pressure consistent. If you are using preground then you will want to adjust the amount of coffee you put in the filter basket and the tamp pressure. Be sure not to overtamp or exert too much pressure on the puck of coffee or you can cause channeling. Channeling causes a channel or fracture to open in the puck through which all of your brew water will try to flow, making for a very uneven or poor extraction. Ideally, you also want your tamped grounds to be level so that water flows evenly throughout the puck. If tamped unevenly, water will flow to one side of the puck.
The Golden Rule
A reliable method for judging your extraction times is by following the “Golden Rule” which states that a double shot of espresso should result in about 2-2.5 fluid oz and take about 20-25 seconds to extract. Keeping this in mind gives you a good measure for what kind of adjustments can be made to grind size and tamping pressure. If your extraction is too fast, you would want a finer grind size. Too slow, and a coarser grind size would be best. Make sure the only variable you have is the grind size, keep the dose and tamp pressure consistent.
The Specialty Coffee Association states that the ideal brewing temperature ranges between 195 to 205, which should result in a shot that is around 160-165 degrees in the cup. Your drink should be hot to the touch, but it shouldn’t scald you. For Heat Exchangers, you’ll want to perform a cooling flush if the machine has been on but not brewing for some time. You can do this by running brew water out of the group head for a few seconds to remove any overheated water from the system. Other prosumer equipment, especially those with PIDs or Dual Boilers, should have stable temperatures as long as the machine has fully heated up. Be sure to leave the portafilter locked in while the machines heats to make sure no heat is lost while brewing. Remember to pre-heat your cups with steam or hot water before pulling your shot to maintain a hot cup of java.
The big choice. There’s a multitude of features and finishing touches to any given machine, but the simplest way to approach deciding which machine to purchase is to first consider the boiler type. You’ll find single boilers, heat exchangers, and dual boilers.
Single Boiler Dual-Use
- Single Boiler Dual-Use espresso machines are the most basic semi-automatic models. These machines have a single boiler that is used for both brewing espresso and steaming milk. The small size and low cost provide an easy entry into home brewing. There are also higher end machines with single boilers that are equipped with PID temperature controllers. These machines are often purchased by people who are more interested in precise control over the temperature of their and may not be concerned about milk steaming.
- These espresso machines are some of the most commonly found machines in the Prosumer category. Designed with boilers that feature heat exchange technology they can brew and steam simultaneously by maintaining a constant supply of both steam and brew water. The basic concept is the brew water is in a small tube that is supplied with fresh water each time you hit the brew button or ever to brew. That tube goes into the boiler and the large mass of boiling water surrounding the tube heats the water as it passes through. Heat exchange machines are a great choice for developing brewing techniques. They offer better temperature stability, higher capacity, and professional grade components. Learning how to brew at consistent temperatures can be learned but is not what these machines are generally well known for, particularly when compared to a double boiler machine.
- Dual Boiler espresso machines are built with two boilers instead of one. Each boiler has its own dedicated application (brewing or steaming respectively) and in most cases the steam boiler can be switched off when not needed. Dual Boiler machines feature many of the same benefits and design features present in Heat Exchange models such as high capacity, water line adaptability, rotary pumps, E61 Groups, and the ability to brew and steam simultaneously. They are typically found on the most powerful machines available.