Written by Joshua for www.espressoplanet.com as an entry level guide - The Espresso Planet Home Barista Training Course.

The standard espresso is between 6.5 - 9g and approx. 21-33ml (0.5oz - 1oz) of water for a single while 14 - 20 g of grounds to 33-66ml (1oz -2oz) of water for a double. Standard extraction pressure is 8-9 bar and standard extraction time is 20-35 seconds. The standard Temperature can range from 185F-204F (85-96C).

Definition: Small, made to order, concentrated coffee consisting of liquid topped by foam or crema.

Some Terms: (designed to give you the basic understanding, you should do some more reading on these terms)

Variables: Brewing espresso is made up of, you guessed it, Variables. How hard you tamp, the temperature, grind, extraction time will all affect the final result. Try and keep all variables the same when brewing. To fine tune your espresso, keep all variables the same and only change one variable at a time to see the results. A notepad is handy. Write down all your variables and what you changed and the results.

Grind: The process of grinding whole beans in preparation of brewing under pressure. The grind is extremely important and is paramount for proper extraction. Each machine is different. Each brewing method requires a different grind. Espresso requires a fine grind and extremely consistent particle size. French Press requires a coarse grind. Each type of Espresso machine requires a different grind. Pressurized portafilters require a coarser grind than a standard portafilter like the Rancilio Silvia, and so on.

Roast: The process of turning Green beans into coffee beans ready to use. How long you roast for helps to determine flavour. The longer the roast the darker the roast, usually bringing with it, stronger flavors and a dark colour. The darker the roast, the oilier the roast. Please read up on different types of roasting and the effects.

Temperature: Temp. will affect the final outcome of your espresso shot. Without going into too much detail, generally speaking, the hotter the temperature, the more “bitter” your shot. The lower the temperature the more “sour” the shot.

Tamping: Using a tool called a tamper on traditional machines or a brewing unit on Super-Auto machines, a flat or convex surface presses down on the ground coffee. The standard is 30LBS of force when doing by hand on a traditional. Harder tamping increases the resistance for the water, therefore it can be used by a barista to adjust his espresso shot. Less tamping force = less restriction and more tamping force = more restriction. Restriction directly affects extraction.

Extraction: Extraction is the removal of mass from the grounds. Extracted substances are either soluble or insoluble. You can think of Soluble as solids and gases dissolved in the brewing liquid. Soluble solids contribute to strength and taste while soluble gases contribute to aroma. Insoluble are held in a suspension or emulsion. The suspended solids are mainly bean cell wall fragments that contribute to body but not flavour. The Emulsion is a dispersion of oil droplets from the coffee that get surrounded by liquid which contribute to aroma body and taste. These also help to decrease the bitterness of your espresso by “coating” your tongue.

Over Extraction: Over extraction will cause a white substance to form on top of your crema. Over extraction can be caused by a number of variables. Your grind could be too fine causing you to extract too much from the coffee. You could have too little coffee, again causing too much to become extracted. Your temperature could be too high. Over extraction will cause your espresso to taste overly bitter.

Under Extraction: Under extraction again can be caused by a number of variables. Either your grind is too coarse, causing the water to rush too fast through the coffee bed not extraction enough mass from the grounds. You did not tamp hard enough, or your temperature was too low. Under extraction will cause your espresso to taste overly sour.

The Seeds:

It all starts with the coffee itself. Without quality coffee, how are we expected to produce quality drinks?

Coffee beans are in actuality the seeds of the fruit from a coffee plant which averages a height of 5-10 meters. The seed is the pit inside the red or green fruit often referred to as the cherry or berry. There are two main strains of coffee seeds. Approximately 80% of coffee produced is called “Arabica” while approximately 20% of coffee produced is called “Robusta”. Arabica beans are of a higher quality then Robusta beans, while Robusta beans contain more caffeine. Robusta generally has more of a bitter taste, while it produces more sustaining crema then 100% Arabica blends. This is why you will see a lot of blends containing from 15% to 60% Robusta. This gives an intense taste and a LOT of crema. The more knowledgeable / enthusiasts will insist a good espresso can only contain 100% Arabica beans.

There are also many different coffee growing regions, each with there own set of characteristics. A good “Cupper” can usually tell where the coffee was grown based on a single slurp / smell of the aroma. Soil, rainfall, altitude are some examples of factors which affect the quality and taste of the coffee.

There are two methods of processing the coffee berries. The first method is wet processing, which is usually carried out in Central America and areas of Africa. The flesh of the berries is separated from the seeds and then the seeds are fermented – soaked in water for about two days. This dissolves any pulp or sticky residue that may still be attached to the seeds. They are then washed and dried in the sun, or, in the case of commercial manufacturers, in drying machines.

The dry processing method is cheaper and simpler, used for lower quality seeds in Brazil and much of Africa. Twigs and other foreign objects are separated from the berries and the fruit is then spread out in the sun on cement or brick for 2–3 weeks, turned regularly for even drying. The dried pulp is removed from the seeds afterward.

The beans are ready for shipping.

Roasting

Once green beans are imported they need to be roasted in order to be consumed. There are two types of coffee roasters – Micro roasters and Macro Roasters.

Micro Roasting:

Micro roasters generally roast in batch sizes from 150 pounds to 300 pounds at a time. They are more expensive to buy from but generally make up for it in quality and freshness. Most of the highest rated coffee roasters are considered micro roasters. The small batch sizes allow the roast masters to have much more control and much less automation. Roasting smaller batch sizes also allows for more consistency, bag after bag. They will also usually try and work with the farmers and fight for fair trade.

Some examples of Micro-Roasters: Intelligentsia, Stumptown, Detour, Social, Counter Culture, Klatch, Ritual and Barefoot.

Macro Roasting:

Macro roasters supply the big boys like Second Cup, Tim Horton’s, Coffee Time, Starbucks and most chain accounts. Most of the roasting plant is automated, controlled by computers and roasted sometimes in 1000(s) pound batches.

Grinding:

Grinding: As taken from www.coffeegeek.com

The grinder is an integral, necessary part of making good espresso in the home.

”Why the grinder is important…

Espresso preparation is harsh. It's just about the harshest brewing method you can throw at a coffee bean and still produce something that tastes heavenly. Percolators can't do that. Even moka pots are finicky as all heck. Espresso brewing, using over 135 pounds of water pressure per square inch, extracting in 25 seconds, is near-torture for the ground coffee bean.

If you ask them for their secret, besides talking up good ingredients (quality, fresh roasted coffee, good water) and having a developed skillset for producing espresso, they'll all mention one other key thing: the grinder. One core item they all have in common is a quality grinder to freshly grind the coffee to the very precise particle sizes necessary to good extraction. Often, the grinder is the rock star of their little espresso show.

I've often said that I can make a better shot of espresso with a $200 espresso machine and a $400 grinder than I can with a $2,000 espresso machine and no grinder (or a blade grinder)... and it's absolutely true.”

The purpose of grinding coffee beans is to increase the amount of coffee exposed to water. You increase the surface area by grinding smaller; grinding smaller as in grinding finer. The finer your grind, the more surface area is exposed to hot water meaning the more you will be extracting. Remember, extraction is the amount of TDS (Total Dissolved Solids) you can extract from ground coffee. The finer your grind, the more you will extract. That is the basic principle of grinding coffee. – JM.