Revision as of 10:31, 1 February 2017

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.

The Basics

There are four main elements of espresso brewing which are going to produce the end result. They are commonly called the 4 M's of espresso brewing. The 4 M's stand for Miscela, Macinadosatore, Macchina, and Mano. Roughly translated they mean the type of coffee used, the grind and dose of the coffee, the brewing equipment, and the user. The user and the type of coffee being used are particularly important, but all four of these elements need to work together to produce good results.

Type Of Coffee

Since espresso extraction is a much more concentrated brewing method than other coffee brewing methods the quality of the bean is going really important. Espresso concentrates and amplified 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 and grinders are not compatible with oily beans for example. Using fresh beans, which were only opened within the last two weeks is important. Coffee is like other food and it does deteriorate and become stale/rotten. Typically we suggest a light/medium roast that is dry, roasted within the past two weeks, and roasted dry with no excess oils. We caution against excessively dark roasted or oily beans because this roasting style is frequently used to mask flavor defects within the bean.

To maintain the freshness of the bean it's important to store them properly as well. Improper storage can cause them to deteriorate more quickly, resulting in unfavorable flavor changes and a lack of crema.

Grind & Dose

The grind and dose of the coffee are important in controlling the extraction rate of the coffee. 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. Different machines will have portafilter baskets that accept different amounts of ground coffee. For example on a Rancilio Silvia the maximum accepted dose for a double shot is 14 grams but on a large prosumer unit such as the Expobar Brewtus IV the typical doubleshot dose is going to be about 18-20 grams. If you are unsure what a good starting dose is for your machine consult with our Technical Support or the machine's manufacturer. For the sake of consistency it's important to select one dose amount and work from there.

If you have a machine that features a brew pressure gauge and you find that even though your shot timings are correct the brew pressure is low and the coffee is weak then this is a sign you may be underdosing. Check to see what dose is appropriate for the shot size you are brewing.

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. Consistency of the grind is particularly important in espresso brewing because it's desirable to have most of the individual coffee grinds to be similar in size. Water like to take the path of least resistance, so when the shot pressurizes the water is going to take the easiest path through the coffee. If there are lots of grinds of all different sizes the water is going to ignore the smaller grinds and only flow around the large grinds. This will result in an uneven extraction, and is typically indicated by channeling in the coffee puck, which looks like dimples in the coffee puck.

Consistent grind will cause the water to distribute evenly across the entire coffee puck. Since all of the grinds are almost the same size there isn't a path of least resistance. There is even resistance across the entire coffee puck, which forces the water to flow through the coffee evenly.

In general the high the quality of the espresso machine the higher quality grinder you will want to go along with it. Even a great espresso machine will not pour good shots if there is a defect in the tamp/grind. Overcompensating with one aspect of the 4 M's will not make up for another one of the aspects if it is lacking. We suggest checking with our Sales department, or the espresso machine manufacturer for suggestions of a grinder that will pair well with the espresso machine. Burr style and size, burr material, motor power and rpm, doser vs. doserless, and many other factors should all be considered.

A blade grinder will not be suitable for espresso brewing. Blade grinders produce extremely inconsistent grind; frequently large chunks will be mixed in with finer grinds and lots of powdery residue.

Once you have a grinder you will need to make some basic starting adjustments. Generally you will want to start with a grind that is a little bit finer than table sugar/sand. Please be aware that burr grinders should only be adjusted in the finer direction while the burrs are running, and should be started on a coarse setting and then slowly moved down to the espresso range. This prevents clogging in the grinder, or damage from the burrs touching each other.

Once you have your grinder set to the correct starting range, then you will need to make further adjustments to the grind size to achieve the correct shot timing. The golden rule is to pour 2 oz. in a 25 s. period. If the 2 oz. pours through in less time then the grind is too coarse and needs to be moved finer. Alternatively, if it is flowing through too slowly then the grind needs to be move more coarsely. Keep in mind that the closer you get to the correct shot timing the smaller the adjustment you should make to the grind size. A small change in the grind size at this point can make a big difference in the shot timing. This gives grinders that have infinite adjustment over stepped adjustment a clear advantage, since you can make however small/large of an adjustment you want.

Another thing to consider, especially on a new burr grinder, is that the grinder will require seasoning. You may find the grinder clogs easily at first, or is particularly sensitive to adjustments or requires frequen adjustment. This is perfectly normal and to be expect. Most manufacturers don't preseason their burrs because it significantly reduces the lifetime of the burr.

Another thing to bear in mind is that there are many factors that determine how a bean is going to grind up. The roast, bean size, bean hardness, oil content, age of the bean, and even ambient temperature/humidity have an effect. This means that your grind size is a changing variable. Regular adjustments to the grind size are to be expected to maintain the proper shot timing.

Brewing Equipment

There are several categories of espresso machine which all use the general espresso extraction process of applying heat and pressure. Some machines are more geared for convenience than quality, while others are very focused on quality and controlling the process, such as prosumer machines. The important thing to consider is that each espresso machine will have its own personality, so what works on one machine won't necessarily work on another machine. There will be differences in design intent, intended use, parts quality, etc. that affect how the machine will interact with the coffee and your other equipment.

Generally the higher the quality the machine the better control the machine has over variables like temperature and pressure, producing a higher quality product. Adjustment and set up considerations will be fairly specific to the machine make and model. You can find more information about your machine on it's wiki page by locating it through [supported brands page.]

User

tamp distribution

Brewing Example

Bottomless/Naked Filters

Ratios & Timing