# Coffee Module Two


# Barista's in Specialty Coffee

In the Specialty Coffee Industry every step in the process from seed to cup is crucial and important as quality needs to be maintain from the beginning of the chain at production in origin to the end consumer in a café or at home. Perhaps one of the most important is the barista’s role as it is the last step in the specialty coffee chain. He/she is responsible to transfer the quality of a certain coffee from the beginning of a chain to a brewed beverage. As coffee quality can only drop from the beginning of the chain to the end of the chain, acknowledging that they can’t add quality to the coffee but can only take away.

The Barista is the final contact of this coffee before it reaches a consumer so it is also important that the baristas represent the industry and the craft to a certain degree so the specialty coffee industry is respected.

The Baristas are the ones who have the direct link to customers and are able to educate consumers about specialty coffee, the more educated the consumers are about specialty coffee the higher the opportunity for progression in the industry.

The Barista must acknowledge the natural characteristics of certain coffees, its roast profile, brew methods amongst many other factors to brew coffees that best showcase and highlight the coffee but also being aware that excellent service is also a priority as we are in the hospitality industry after all.

# Varietals

The first coffee trees known to be cultivated originated from Ethiopia and known us as today as the Typica varietal, however due to the fact that Ethiopia is the birth place of coffee there are a lot of unknown varietals being cultivated which make it hard for us to singularly pick out certain varietals so in most cases all bags of Ethiopian coffees will state that they contain mixed heirloom varietals.

Many other varietals that we are familiar with today are a result of either natural mutation and cross breeding either through experimentation or through natural. Some varietals have their own specific taste characteristics while others take on their characteristics from the terroir in which they were grown in or the way they are cultivated to the way it’s been processed. Here are some of the more common varietals that we are familiar with:


Considered to be the original variety and is still grown extensively around the world. Fruit is usually red and is capable of producing excellent cup quality. This varietal is relatively low in yield quantities compared to other varietals.


A natural mutation of Typica, its yield is of higher than Typica and is believed to have a distinctive sweetness, making it prized and desirable. There are variations of fruit colour of yellow and red and sometimes orange.


A natural hybrid of Typica and Bourbon, grows a relatively high yielding strength and disease resistance.


A hybrid between Caturra and Mundo Novo, its favored because it combines the dwarf characteristics of Caturra with the high yields and strength of the Mundo Novo Varietals. There are red and yellow varieties.


A mutation of Bourbon, high yielding and is very polar in Colombia and Central America. Both red and yellow variations and is a lw growing varietal, which makes it good for farmers for selective picking of fruits.


Created in Kenya by Scott Laboratories. This varietal is considered to be capable of producing very distinct fruit flavours often described as blackcurrant. Performs better at higher altitudes.


This varietal is also capable of distinct fruit flavours but is generally inferior when compared to the SL-28 varietal.


Believed to be Ethiopian in origin, this variety is known to produce exceptionally floral/aromatic and because of it high demand, the prices for Gesha’s has been driven up significantly over the past few years.


It has extremely large leaves, fruit and coffee beans, it has distinct cup characteristics and can inhabit flavours of chocolate and fruit.


A natural mutation of Bourbon and cup qualities similar to Bourbon. Low growing so its desirable for pickers.

# Freshness

Coffee is a fresh product, it must be brewed and consumed fresh to experience the best flavours and aromas, keeping in mind that certain coffees taste its best at different times and not always at its freshest e.g. some coffees taste at its best around 3 days from roast and some will taste great at 2 weeks from roast. The life cycle of roasted coffee beans can be anywhere from 2 weeks to 2 months from the roast date, after the desired life cycle the coffee starts to go ‘stale’ the deterioration in quality where flavours become sour, dull and flat. The life cycle of coffee is dependent on several factors including:

Roast Profile With lighter roasted coffee the cell wall of the coffee is much more dense and the holes that release CO2 gas is smaller so it takes a longer period of time for lighter roasts to go “stale”. With darker roasted coffees the cell structure is less intact and is broken down more which means that the holes which CO2 gas is released is much larger and beans rapidly release gas very early from roast date and go “stale” quicker.

Oxygen All coffee must be stored in airtight packaging to prevent or minimize oxidation from occurring.

Moisture As coffee is hydrolytic (breaks down with water) steam and condensation will degrade its quality and freshness, which is why we should never store coffee in the fridge or freezer.

Light Exposure to light can trigger oxidization in coffee, this is why coffee is packed in opaque packaging, inhibiting any light from penetrating the coffee.

Odours Due to its fresh nature, coffee can absorb other flavours from contamination.

Temperature Store between 5 -25 degrees Celsius. Like wine coffee must be stored at an ambient temperature as extreme temperatures will contribute to speedy deterioration.

# What is Espresso?

The definition of an Espresso has been changing and evolving over the years as people in specialty coffee industry are experimenting and pushing different methods and manipulating extractions to create ‘espresso’.

However Espresso to date on average is created when water, heated to a minimum of 88-96 degrees Celsius is passed through a controlled and measured amount of finely ground coffee at an average of 8.5 to 9.5 bars of pressure (atmospheric pressure) for a period of 18-32 seconds producing anywhere from 30 – 60 grams of espresso. Anything significantly outside this range is not really considered espresso.

Roasted coffee is made up of 30% Soluble Solids and 70% Insoluble Solids (mostly plant material). When we extract coffee, in general we are extracting soluble solids out of a coffee and leaving the Insoluble behind in the “puck”, the coffee cake left behind after extraction in the portafilters.


Many factors in the coffee alone will definitely effect what coffee tastes like and how its extracted as an espresso, the two factors that impact extraction the most will be:

Roast Profile When coffees are roasted darker, the coffee when being extracted as an espresso will be more soluble, meaning desirable flavours will extract out of the coffee quicker than if the coffees are roasted lighter. So that’s why our darker coffee roasts are extracted at a shorter yeid, yield meaning the amount of espresso that’s extracted out of the coffee. E.g. a darker roasted coffee might extract 35g of espresso yield while a lighter roasted coffee might be tasting great at a 55g yield, depending on the coffee of course.

Age When coffee is roasted it will start to degas slowly releasing CO2 gas, the freshness of the coffee will affect the extraction. Because coffees when freshly roasted still contain many gases it will actually make it harder to extract, the gas particles repel water molecules away from the coffee and are not in full contact with each other therefore not extracting fully. Comparing to coffees that have been degassed the gas particles are at optimum so that extraction is at optimum. General speaking the fresher coffees are the finer the grounds need to be to allow for more water contact, and coffees that are degassed longer require a coarser grind.

Degassing time will vary depending on the coffee could be from 3 days to 2 weeks for optimum aging.


Your machine is also unique, performing much like a car, different between makes and models. However, they will all have similar qualities and features, especially the crucial points like being able to extract coffee at 9 bars of pressure and produce steam for milk.

The 2 main types of machines that we stock and use here at Code Black:

Timed Is programmable to set the desired time of hot water passing through the group heads e.g. the group heads are set to 23 seconds and will stop when that time is reached regardless of how much water is passing through unless manually cut to stop shorter.

Timed machines: La Marzocco Strada Ep

Volumetric Espresso Machines that are programmable to dispense a set volume of hot water passing through each group head, e.g. the group heads are set to a yield of 45g, the group heads will stop passing hot water through when the yield has been reached regardless of time.

Volumetric machines: La Marzocco Linea / La Marzocco Linea PB / Victoria Arduino Black Eagle / Synesso MVP


You cannot make a good espresso unless you have a good consistent grinder that produces even grind size particles. Coffee is ground to a particular particle size to form resistance as water passes through it to ‘extract’ if the grind is too fine too much resistance is occurring meaning that the coffee is in contact with water too long which will result in over extraction.

If the grounds are too course, water is flowing through the grinds too fast which means that water has not had enough time of contact with the coffee to extract the desired flavours out of the coffee.

The 2 main types of grinders that we stock and use at Code Black:

Conical Burr Grinders The Burrs (metal blades that cut/crush coffee) that grind coffee are a cone shaped that has a larger grinding surface area which results in much faster rate of grinding however it is known to produce a significant amount of inconsistent grind sizes, larger and smaller particles that have a large variation between them. Conical burr grinders: Mazzer Luigi Robur Electronic

Flat Burr Grinders The Burrs that grind coffee are flat and only crush (not cut) coffee to produce a evenly consistent grind size, the grinding time will take significantly longer but will allow your coffee extractions to be more even (uniform extraction of solubles within the grounds).

Flat burr grinders: DC (Della Corte) One / DC Two / Mahlkonig EK43


As a barista it’s important to adopt consistent techniques as well as effective ones, these techniques are all basically to help promote ‘even extraction’ the term used to explain that the ground coffee particles in the coffee basket all have the same amount of contact with the water so that the flavours being extracted are uniform.

# Extraction Basics

Here are some important barista techniques/terms you need to master and understand:


A coffee ‘dose’ means how much of the dry ground of coffee you are using in your basket in the portafilter. In order to understand your extraction, you must use a consistent dose, you need to know how much dry coffee you’re using every time to produce consistent espresso’s. In order to do this you must use a scale with increments of 0.1 of a gram.

Steps to dose a coffee:

  • remove portafilter from group head, the portafilter needs to be hot, dry and clean.
  • flush group head, run a little water through the group head to ensure clean water is available for the espresso
  • tare the portafilter on the scales to ‘zero’
  • grind a set amount of ground coffee into the basket of the portafilter, adjust grinder to dispense an dose as close as possible to your set dose for the espresso.
  • place portafilter back on scales and check dose amount, adjust if necessary.


Means how evenly distributed the grinds are in the basket of the portafilter. Even distribution is what we strive for so that when we tamp onto the grinds the bed of the tamped coffee has even density throughout the whole puck allowing for the water to flow through evenly. Even if you have an even tamp on a poor distributed coffee, the tamped coffee puck will look even however it isn’t, parts of the coffee cake will have more density of coffee than the other and when 50 Kilograms of water pressure is pushing through the small cake of coffee the high pressurized water will flow through the path of least resistance, over extracting the part of the coffee with less density and under extracting the part with more density.

A good distribution technique that seems to be effective/ consistent and efficient is the tapping method where using the palm of your hand to tap the side of the undistributed coffee grinds to create a level bed of coffee before tamping.


Means that water has found an easy path through the coffee cake which means there is no resistance with the coffee cake and therefore not extract the desired flavours. The liquid coming out is gushing (really fast) which means that there would either been a crack, or a hole in the puck of the coffee cake prior to extraction. This can happen to any skilled barista whether they might’ve bumped the handle before inserting it into the group head or tamped incorrectly, but it’s important to acknowledge this and not serve it.


Coffee must be tamped before insertion of the portafilter into the group head. The reason why we tamp coffee is so we expel any air in between the grinds of the coffee in the basket and to produce an even flat surface that will offer equal resistance to the water passing through. An even surface will promote an even extraction.

The tamping pressure of the coffee will differ between each individual however you should always try and reach maximum density, meaning that you physically can’t expel any more air out of the grounds without changing the physical shape/ structure of the grounds.

For an effective tamp they must be level and even so the water will flow through the coffee cake evenly.

Depending on your tamping technique and/or tamper sometimes the coffee cake (tamped dry grounds of coffee) can create a vacuum suction when lifting off the tamped coffee and might move the grounds creating a crack around the edges of the coffee cake, this will promote channeling and not give you a good/even extraction.

A good habit to develop is to look at the tamped coffee cake after tamping, it should be flat with no cracks or holes in it.

# Brew Ratio

A brew ratio defines the amount of dry coffee used (dose) to the amount of coffee extracted out (yield). Usually its represented in a dose:yield manner. For example: if I’m using a dose of 20g of dry coffee grounds and extracting 40g yield of coffee that is a 1:2 brew ratio.

Brew ratios are really important as it has a big impact on the strength of your coffee, flavour and extraction. Extraction meaning the amount of solids extracted from the coffee into the brewed beverage.

The shorter the yield and lower the brew ratio the stronger your brewed coffee. This will also mean that your coffee will have a lower extraction.

This is because there is less water in the beverage so that the concentration of coffee is higher but because of the lower water content its not extracting as much (carrying through) from the coffee eg. At a brew ratio of 1:1 the coffee is short and strong for example, 20g of dose and 20g of yield will produce a short thick oily, strong coffee that has a short/lower extraction.

The higher the yield and higher brew ratio the weaker your brewed coffee. This means that your coffee will have a higher extraction.

A coffee brewed with a 1:3 brew ratio for example, 20g of dose and 60g of yield will produce a coffee that is weaker because of the added dilution of water but will have a higher/longer extraction, we have extracted more out of the ground coffee.

The 3 main variables to understand and will help you produce consistent espressos are:

Dose - The amount of dry ground coffee used The most important variable and should be locked in with very minimal variability because this will allow us to know how much of the coffee we are extracting to reach a certain amount of yield. If we don’t know how much dry ingredient we are using we won’t know what we are extracting out of it.

Yield - The amount of brewed coffee extracted The 2nd most important variable that should be locked in. different coffees will require different yields of extraction so we know the strength of the coffee as well as what we’ve extracted out of it.

Time - The time is takes for the amount of dose to achieve the desired yield of coffee The 3rd most important variable and should be treated as a micro adjuster, it’s also a number that helps us with knowing how consistent our shots are in achieving a certain extraction and brew ratios. Time should be the only variable with a range eg. 23-26 seconds is acceptable for a certain coffee, when outside this range adjust grind size to get it in the range.

Brew recipes

A brew recipe is basically the amount of ground coffee used to a achieved a certain yield over a certain time period. For example a particular coffee is tasting great at a brew recipe of 20g dose – 45g yield – 26 seconds.

Different coffees will require different brew recipes to achieve the desired flavour and strength, these are all dependent on several factors like:

Intention of the beverage, for black or milk based beverages: Milk based beverages ideally we want an espresso that’s shorter in yield so that the strength of the beverage is higher so this can carry through with the addition of milk. Black based beverages are generally pushed to a longer extraction with a higher yield to create balanced and to pull out as much positive flavour out of the coffee as possible.

Equipment available, especially grinders Grinders that use conical burrs will produce more inconsistent grinds sizes, which means that extractions can’t be pushed very high with larger yields as the finer particles will over extract and result in a bitter brew. Grinders that use flat burrs will produce a more consistent grind size allowing us to push extractions further and reach higher yields without it becoming bitter.

Roast profile darker and lighter roasts Darker roasted coffees will extract flavours quicker out of the coffee so generally darker roasted coffee require a shorter yield and extraction. Lighter roasted coffees will take longer to extract flavours out of it so generally lighter roasts allow for a larger yield and higher extraction.

Steps on preparing an espresso with a given recipe. Recipe example:

Ethiopian Aricha

Dose 20g / Yield 52g / Time 23 – 26 seconds

  • Remove portafilter
  • Flush Group head
  • Knock out old coffee puck from portafilter
  • Wipe and dry basket to remove water and residual grounds
  • Grind coffee on demand and adjust to correct dose of 20g
  • Distribute the coffee evenly in the basket using the tapping method
  • Tamp coffee, creating a level and even surface
  • Wipe away loose grinds from the portafilter (If manual extraction, weight and tare out a cup on a small scale on the drip tray)
  • Lock the portafilter in place and start extraction immediately, when this stage is prolonged it aids in the oxidation process and makes the coffee go stale very quickly
  • Watch extraction to see if theres any problems eg. Channeling or if drips are coming out of one side of the spout (If weighing the shot on scales, stop your shot around 4-6grams before the desired yield as the remaining drips will make up the rest of the yield)
  • Check the time of extraction and see if it’s within the time frame.

There is a bit of science to steaming milk as with the rest of espresso making. The 3 main things we look for in cold milk for coffee preparation are as follows:


The good stuff where it really effects the tactile of the beverage and latte art


Lactose, made up of galactose and glucose


A long chain of amino acids which when in cold milk are all wound up. The hydrophobic molecules of the protein are buried inside the coil because they do not like water. The proteins is what creates Micro foam.

When milk gets heated these 3 components change:

Fat: Gets thinner and melts

Sugar: Breaks down into smaller simpler sugars which have a sweeter taste, we perceive milk to be at its sweetest around 60 - 65 degrees Celsius

Protein: The coil loosens up and the hydrophobic molecules (enzymes) become exposed and look for somewhere to go. The hydrophobic molecules will attach themselves to the closest substance to them which would be the bubbles formed by air, they encapsulate the air bubbles with a skeleton of protein thus holding its structure and thats what we call Micro foam. However the hydrophobic molecules become denatured and don’t do anything when the temperature exceeds 37 degrees celsius, the temperature we feel ‘warm’ at.


Start with milk below 7 degrees celsius and introduce air (stretch) until 37 degrees celsius. This step will ensure that the air introduced into the milk will turn in microfoam.

Once the milk has reached 37 degrees celsius it’s important not to stretch the milk anymore but still maintain a whirlpool and increasing the milk temperature to 60 – 65 degrees celcius, usually this temperature is when the jug is too hot to hold for more than 3 seconds to the touch. Heating the milk over 70 degrees celsius will allowing for souring and scalding of the milk.

# Cleaning and Maintenance

Every Coffee

  • Flush the group head with water after every coffee to remove residual grounds.
  • Wipe out residual grounds from the filter basket after each extraction. Ensure baskets are clean and dry
  • Wipe and purge steam wand with a damp cloth after every use. This action will help prevent build up or blockage of milk in the steam tip.
  • Maintain a clean working area, including sanitizing milk jugs, cloths and benches throughtout the day.

Every Hour

  • Back flush each group head with fresh water and a blind filter to remove trapped or retained residual coffee from the group heads.
  • Take out the filter baskets from each portafilter and clean the baskets removing all the dried oils and residue left on the baskets especially the bottom, clean and dry the insides of the portafilter and heat up again with hotwater from the groups.


  • Soak group handles / filter baskets / shower screens / dispersion blocks in a bucket of hot water with a teaspoon of espresso cleaning product, soak only the metal components (not plastic handles) for 15 minutes and scrub free of any coffee build-up and caffeine stains. Rinse clean under hot running water.
  • Back flush the group heads with a blind basket and espresso cleaner. Half a teaspoon per group head is sufficient. Start the cleaningcycle and allow it to run for 10 seconds to dissolve the cleaner, stop the cycle and allow to sit for a further 10 seconds. Start and stop this cycle 4 times. Tip out any chemicals left in the blind basket and rinse before repeating again without chemicals until water runs clear.
  • Empty the grinder of any remaining coffee, use a dry brush to remove any loose grounds in and around the grinder, dry steam and wipe out the bean hopper with paper towels.
  • Remove and clean drip tray
  • Use a glass cleaner and a soft cloth to polish the coffee machine
  • Soak steam tips in hot water or steam wand washers, use a paperclip to unclog holes if blocked