black notes

A brewer's guide to the galaxy!

What is coffee?

COFFEE IS FROM A FRUIT.

In commercial coffee production there are two species of coffee used for consumption Arabica and Robusta.

At the moment we at Code Black only buy Arabica Green Beans (Unroasted Coffee) to roast as Arabica is known to be the higher quality out of the two, however the specialty coffee industry are experimenting trying to improve the quality of Robusta coffee and we could be purchasing Robusta in the future if they are up to standard.

Just like all fruits they range in varieties e.g. In wine there’s varietals of grapes like pinot noir, chardonnay, pinot gris.

Within the Arabica coffee species there are dozens of different known varieties e.g. Typica, Caturra, Catuai, Bourbon etc. Each variety will have different characteristics whether it be taste or aroma to production yield or disease resistance.

Just like all fruits, coffee naturally will contain acidity and sweetness. The toasty, nutty or roasted flavours only develop from roasting where sugars from coffee are caramelized; this is how we know the common taste of coffee. However, the darker the roast doesn’t mean the better the brew as this is a common misconception, for example take a nice piece of eye fillet steak we all prefer it to have a nice toasted flavour but we still want it cooked to a certain point eg, medium rare to showcase the quality of the meat and its natural flavour. Same with coffee, it should be roasted to a point where the preferred flavour profiles are highlighted generally between light to medium roast.

Coffee is a brewed beverage made from an extraction of roasted seeds from the cherries produced on a coffea plant, which is known as a coffee tree.

The coffea plant is native to subtropical African countries and some islands in southern Asia.

What is specialty coffee?

To put it simply specialty coffee is quality coffee.

Like the fine wine of coffee, where quality is maintained from seed to cup and having every stage of the beans life cared for, starting from the farmer also known as the producer who’s dedicated their lives into producing and focusing on quality not quantity.

At this stage only coffees that are free from defects and are at optimum ripeness will be passed on to the next hands in the chain.

It is from here where the farmer must be able to recognize that their coffee goes to like-minded people in the chain to ensure a higher profit.

The green processed coffee then goes to the green coffee buyer who is either certified as a coffee taster with a Q grader certification just like a certified sommelier or green buyers with great cupping/industry experience and knowledge, they will be able to determine the quality of the coffee and pricing of the product which is then determined if the coffee is deemed specialty or not.

For coffee to be labelled as specialty it needs to reach a score of over 80/100 when coffee gets cupped by industry professionals not always necessarily by Q graders.

Cupping is the industry method of tasting and assessing coffee quality similar to wine tasting.

The coffee is then sent to a roaster where the coffee is roasted to a specific degree to highlight the flavour profiles that are preferred. From here the barista recognizes that the coffee has gone through 3 stages of quality control and it is their job to brew the consumer a delicious coffee and minimize any loss of quality from the beans. The Barista cannot add quality to the coffee but instead tries to ensure that the brew is not compromised in the brewing process and the beans are used to their full potential in the final product.

And lastly the consumer finishes the final step in the specialty chain in recognizing and understanding the efforts and quality put into specialty coffee, as well as benefiting everyone who’s hands have touched the coffee.

Cupping and flavours

Coffee Cupping or Coffee Tasting is the practice of observing the taste and the aromatics of brewed coffee to identify its flavour.

Flavour in general is the combination of 30% taste and 70% aroma.

Cupping is an industry practice that can be done informally by anyone or with strict protocols and guidelines by Master Tasters also known as “Q Graders” to fully assess the coffee. It involves evaluating the coffee after roasting by grinding the beans and steeping it with hot water in cupping bowls after a set amount of time.

The ground coffee floats to the top forming a crust. By breaking the crust a cupper can evaluate the aromatics as they are released. The brew is then slurped from a cupping spoon aspirating the coffee over the palate to obtain the organoleptic (flavour) profile of each coffee.

When cupping each coffee is evaluated by:

Fragrance/Aroma: fragrance of the dry grounds and aromas of the wet

Flavour: combined impression of all the gustatory sensation (taste buds) and retro nasal aromas from mouth to nose

Aftertaste: length of positive or negative flavour

Acidity: often referred to as ‘brightness’ or ‘sourness’

Body: tactile feeling of liquid in the mouth

Balance: how the various aspects of flavour, aftertaste, acidity and body work together or contrast each other

Uniformity: consistency of flavours within the same sample of coffee in different cups

Clean cup: lack of interfering negative impressions from ingestion to aftertaste

Sweetness: pleasing fullness of flavours mostly cause by certain carbohydrates

Defects: are negative or poor flavours that detract from the quality of the coffee

Overall: the overall scoring is meant to reflect the holistically integrated rating of a sample as perceived by the cupper

Like wine, coffee varies in flavour, taste and aroma due to numeral factors.

Some of things that impact coffee flavours are:

Variety: Different varieties of coffee will have specific taste characteristics

Terroir: Is the influence of where the coffee is grown. Some examples:

  • Altitude
  • Climate (temperature, moisture levels etc.)
  • Soil Type
  • Soil micro-biome (Microorganisms found in the soil)
  • Topography (Structure of the landscape)

Farming Practices: Everything from the use of particular chemicals to planting patterns & pruning regimen are ultimately are going to affect the nature of the crop.

Processing: The methods used to turn ripe coffee cherries into dried green beans the 3 most common processing methods for specialty coffee are:

  • Natural – Drying the seeds while still in the fruit
  • Washed – Drying the seeds without the fruit intact by using fermentation to separate the fruit
  • Honey – coffees are dried with some and not all of the outer layer of the coffee cherry removed

Roasting: By turning coffee from green beans to brown roasted coffee with heat we are changing the physical and chemical structure of the coffee, caramelizing sugars, adding roast flavours with Maillard reactions and other chemical reactions.

Brewing: is the final stage in the process from soil to palate, many variables come into play and could change how the coffee tastes. Some important variables are:

  • Brew Ratio (water to coffee)
  • Grind Size (and uniformity)
  • Extraction Time
  • Water Temperature

Counter Culture Coffee Taster's Flavour Wheel (Original source)

Processing: An Intro

The term processing in specialty coffee refers to the methods and preparation used to turn fresh ripe coffee cherries into green beans (unroasted raw coffee cherry seeds)

Coffee beans must be removed from the fruit/cherry before they can be roasted, this can be done in several different ways however there are 3 more common methods used and have a huge impact on the flavour of the coffee:

Natural Processing

Refers to any one of several technological variations where the parchment and skin are dried together.

This where the whole cherries after harvest is cleaned and placed in the sun either on drying tables or thin layers on patios, the cherries are constantly being rotated by hand or with rakes to ensure even drying of the cherries, to reach the desired moisture content of 10 – 12 percent, depending on the region and strength of sun this process can take up to 4 weeks, however some producers have the option of mechanical drying to speed up the process.

Benefits
Because the fruit sugars are drying into the seeds of the green coffee, the results are a heavy bodied (heavy on palate) really sweet, fruity tasting coffees

Negatives
Has a high risk of over fermentation of the fruit during drying

Washed Processing

Refers to any one of several technological variations where the parchment and skin are removed/separated before drying.

In the wet/washed processing the cherries are sorted first by immersion in water where the bad/unripe cherries will float to the surface and the good cherries sink, from here the good cherries are then pulped (squeezing the seeds out of the cherry).
At this stage the seeds will still have a large quantity of pulp and mucilage which needs to be removed, this can be done in 2 ways:

Ferment and Wash:
the pulped seeds are placed in a fermentation tank to ferment away the fruit surrounding the seeds either in their own fruit juice or water, this fermentation can take from 24 -36 hours to complete.

Machine Assisted:
the pulped seeds don’t require fermentation to remove the fruit flesh but instead machine scrubbing to scrub away the fruit substances from the seed.

The cleaned seeds are then dried on raised beds or thin patios in the sun to a desired moisture content.

Benefits
Because the fruits not drying/fermenting into the seeds and is completely removed before drying, the results are a cleaner, acidic/brighter and light bodied coffee

Negatives
Very costly to produce, requires a lot of resources

Honey Processing (Pulp Natural)

Refers to any one of several technological variations where the parchment and a specific percentage mucilage (the fruit layer surrounding the parchment) are dried together with the seed and the skin/pulp removed.

The Honey process is the most difficult and demanding to execute well. The coffee is pulped then spread out to dry without washing, leaving some of the mucilage still attached to the beans, the beans are then spread very thinly on purposely built drying beds and turned hourly for up to 10 -15 days.

Depending on how much mucilage is still attached on the coffee seeds before drying determines what type of honey process it is:

  • Black Honey – 100% Mucilage still attached
  • Red Honey – 75% Mucilage still attached
  • Yellow Honey – 50% Mucilage still attached
  • Golden Honey – 25% Mucilage still attached
  • White Honey – 0% Mucilage

Benefits
This method gives you the best of both worlds with the fine elegant attributes of washed coffees and the substantial body and fruit sweetness of a naturally processed coffee

Negatives
High risk of drying faults, intensive manual labour.

Coffee Roasting (intro)

We may be getting into more familiar territory here but that doesn’t mean that we shouldn’t reflect carefully on the impact of roast profile on flavour. Not even the best roaster can make poor quality green coffee taste great but an unskilled roaster can easily ruin a high graded lot.

A roaster needs to have a good understanding of coffee, its botany, production, chemistry, brewing techniques, growing regions, coffee tastes, its aromatic qualities and most importantly a feel for the roast, it’s a very sense driven craft requiring the use of smell, sound and sight.

Coffee is composed of organic oils, water, protein, starch and vitamins – all of which change during the roasting process. The coffee bean will lose approximately 10-16% of its weight during roast and its mass will increase up to 30%. On average our roasts take 12-17 min per batch.

The coffee first goes through an endothermic reaction and is slowly turning yellow from green, at this stage its basically just dehydrating.

During roasting the cell walls of the bean expand and break as moisture evaporates from within and is released, the noise this reaction makes is called first crack. The roaster uses the cracking sound to indicate the stage of roast the coffee is in and will start to assess and sample the colour change of the beans, from here the coffee is going through what is called a Maillard reaction, basically it’s the chemical reaction between amino acids and sugar reduction that gives brown foods its own desirable flavour e.g. steak doesn’t taste like steak without Maillard, coffee doesn’t taste like coffee without going brown first.

Following this is sugar caramelisation of the natural sugars found in the coffee. Coffee when pushed further in roast can go into what is called a second crack where its hits pyrolysis and develops different types flavour, however at Code Black our coffees aren’t roasted that far as we try and stick into the ranges of light – medium (except for decaf) roast profiles to preserve as much of the natural flavour characteristics produced from its origin.

After sourcing and selection of green the roaster helps to realize the full potential of the coffee by carefully crafting a roast profile that will suit that set of beans. It’s not as easy as light or dark, as roast colour can be very misleading.

The Roaster has to fine tune variables like:

  • Roast time: how long the beans are in contact with heat for
  • Charge Temperature: temperature of the roaster before the beans go into the drums
  • Rate of Rise: speed of the heat increase of the coffee as its roasting
  • Drum Speed: speed of the rotation of the drums inside the roaster
  • Air Flow: amount of air flowing through the roaster during a roast
  • Cooling Speed: rate of cooling for coffee after roasting to room temperature

Brew Methods

Essentially all coffee brewing methods involve using water to carry through (extract) flavour from dry grounds of coffee into a brew (water carrying coffee particles, solids).

Different brew methods will give you different flavours, taste, aromatics, mouthfeel of the same coffee so it’s important to understand what brew method is right for what you’re looking to extract out of a coffee.

There are lots of different types of brewing gadgets and gears out there however most of them will lie under one of these brewing methods:

Pour-over or Filter Brews

In literal terms pouring water over dry grounds of coffee, this method of preparation all involves brewing by percolation meaning water is passed through a bed of coffee grounds extracting flavour as it passes through, usually with a filtration material to filter the groundsbefore the resulting brew. The filter can be anything from paper to different types of cloths to fine metal mesh, the different materials used for filtration will significantly impact the flavour of the brew especially mouthfeel.

Filter Brews with paper filters

Paper filters are the most common type of filter option as they produce the cleanest cup of coffee. They tend to filter out most of the super fine particles that other material tends to miss. Results are a clean, clear, crisp bodied coffee.

Filter Brews with cloth filters

The cloth filter has been used for a very long time but as time progressed less and less people are using it. If done correctly cloth filter brews can be delicious and just like the paper filter methods, it reduces the amount of finer particles passing through and into in the cup. Results are clean tasting coffees with a good amount of body.

The problem with cloth is that it is designed to be reused and is required to be maintained clean and dry otherwise it will leave tainted flavours.

Filter Brews with metal filters

Metal filters are quite a new filtration method designed to be clean and reusable, the mesh holes aren’t as fine as the holes in paper or cloth filters so it allows more oils and finer particles to pass through resulting in a brew with a lot more body and aromatics.

Problem is that it’s quite easy to over extract your coffee and could ruin your brew as the fines that have passed through the metal filter into your coffee continues to extract.

Full Immersion Brewing

A Brewing method where all the coffee grounds are fully submerged into a set volume of water over a period of time and then filtered out using a filtration material either paper, cloth or metal. The coffee and water are steeped together this promotes a more even contact with the grinds and water resulting in a more uniform extraction, because of this your brew will be bigger and richer bodied.

Pressurized brewing

Probably the most popular and common method of coffee brewing outside of home, most commonly known as “Espresso” essentially brewing coffee with applied pressure to extract coffee, this allows us extract a lot of flavours and characteristics out of a coffee that other brew methods cannot achieve, also doing it a lot faster than other brew methods.

This method still uses the percolation theory of water passing through a bed of coffee however done in a very volatile and intense pressure.

Single origin vs blends

Most of the coffee that the world drank a few decades ago was blended, while that’s still probably true across the coffee industry as a whole, in the specialty segment, Single Origins are becoming increasingly popular. This is mostly because it allows the consumer to experience the fruits of the coffee farmers labour (quite literally).

Nevertheless, blending can be a masterful craft in its own right. In its basic form it ensures a consistent flavour experience throughout the year as the parts/inputs of a particular blend will change due to seasonal availability, in saying that consistency of flavour will change but not entirely, however overtime it will be impossible to retain the same or similar flavour characteristics so that’s why it’s a lot more common now that we see blends being called seasonal blends that fully embrace the fact that consistency year round is impossible but rather create a blend utilizing flavours of coffee that is available to us at the time. At its best a blend can be a unique flavour experience, where the flavour is a lot more than just a sum of its component parts.

Single origins offerings are exciting and delicious!

There’s many reasons why we think that here at Code Black, one of reasons is that it allows us truly to appreciate all the flavours and nuances of the coffee from that one particular farm, or region, or cooperative or even one lot of coffee from a particular farm. We get to taste the hard work gone into the coffee and become more educated on how the terroir/ varietals or farming practices to name a few, have all helped us achieve this particular tasting coffee.

What’s great is that certain blends or single origins will taste better with different beverages some blends might taste great as a black coffee and some single origins might go great with milk or vice versa.

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:

TYPICA

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.

BOURBON

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.

MUNDO NOVO

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

CATUAI

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.

CATURRA

A mutation of Bourbon, high yielding and is very popular 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.

SL-28

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.

SL-34

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

GESHA

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.

PACAMARA

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

PACAS

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.

 

Coffee

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.

Machine

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

Grind

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

Barista

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:

Dosing

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.

Distribution

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.

Channeling

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.

Tamping

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.

Milk steaming

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:

Fat

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

Sugar

Lactose, made up of galactose and glucose

Protein

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.

MILK STEAMING

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.

Everyday

  • 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

Coffee Module Three

Solubility

Extraction of coffee is essentially everything that the water takes from the coffee.

Water dissolves a lot of the coffee flavours and pretty much makes up of everything we taste in a brewed cup of coffee, everything else is undissolved solids.

Roasted coffee is made up of 30% soluble solids and 70% insoluble solids (mostly cellulose).

We need both of these types of solids in our cup of coffee to create a balanced beverage as both of these components have certain qualities and traits that are or can be positive /negative when too much or too little are present in a brew.

The soluble solids that are dissolved in brewed coffee contribute to its taste and strength, because the dissolved solids contain most of the coffees flavours. The soluble & volatile aromatics that are found in soluble compounds contribute to its aroma.

The insoluble solids that are present in a cup of soft brewed coffee consist of solids and oils held in suspension. These are generally made up of large protein molecules and fragments of coffee fibre. The Insoluble solids and oils combine to form brew colloids, which contribute to aroma, body and taste. They also alter flavour by trapping and later releasing soluble solids and gases.

The insoluble solids that are in espresso are held in suspension or emulsion, these are primarily made up of coffee bean cell wall fragments, which contribute to body and not flavour.

The oils from the insoluble solids contribute to aroma, body and taste, it also helps to decrease the perception of bitterness in espresso by coating the tongue.

Under Extraction

Under extraction occurs when you have not taken enough flavour out of the coffee, meaning that there is more flavour to be extracted out of the coffee to balance out the undesirable flavours. Common flavours that are associated with under extraction are:

Sourness

Not to be confused with positive acidity. Sourness is when you taste an unbalanced and overwhelming tartness in the coffee and doesn’t have the sweetness to balance it out.

eg. Lemon juice is SOUR, when diluted with water and balanced with sugar; the liquid then contains positive acidity that is palatable.

Lacking Sweetness

When extracting any coffee we want to extract as much sweetness as possible from that coffee, there is never too much sweetness in coffee.

Coffee Sugars (sweetness) is the last soluble component that is extracted out of coffee before reaching undesirable flavours associated with over extraction. So when a coffee is under extracted eg. A Ristretto shot, it is very sour and intense as there’s not enough sweetness in the extraction to balance out the sourness.

Saltiness:

Underextracted coffees are salty, this is because salts are naturally found in the oils of coffee (green and roasted) and when roasted and extracted these oils are present in the form of crema.

If you do a ristretto shot of coffee and skim off the crema, and compare the saltyness of the crema and ristretto the crema is significantly more salty and savoury in taste.

Salt and Acid compounds are more soluble therefore under extracted coffees are salty and sour, the sugars haven’t had enough time and/or water to dissolve into the brewed beverage.

Quick Finish

An under extracted coffee will contain less flavour compounds when compared to a well extracted coffee, because of this under extracted coffee will not present a lingering well lasted aftertaste because it just has less flavour in total, this won’t trigger all parts of your taste buds and will register the flavours being abrupt and unsatisfying.

Over extraction

Over extraction occurs when you take out too much soluble component’s out of the coffee. This level of extraction promotes a lot of unfavourable flavours present in the cup. The two most common and obvious indications of over extraction are:

Bitterness

Coffee is bitter because it contains a high amount of caffeine so we can’t escape bitterness in coffee, however when bitterness is the dominant taste profile of your coffee than that is a good indication of over extraction. There are hundreds of different chemicals in coffee that contribute with bitterness but caffeine being the main one.

Dry distillation is the part of coffee extraction that mostly is associated with darker roasted coffees, its when you have reached over extraction and all the flavour compounds being extracted in this stage are just negative flavours and most of them bitter flavour profiles like ashy, burnt and smoky flavours.

Dryness

Dryness occurs most commonly in over extracted lighter roasted coffees. It’s a sensation that is very unpleasant and is more commonly referred to as astringency or tannic. It’s the same sensation as drinking an unsweetened black tea or biting into a seed of a grape, its “drying” on the palate.

This effect of dryness is caused by polyphenols, this chemical is found in plants, seeds and barks and because coffees are seeds of a fruit, it will contain these chemicals naturally.

Polyphenols are bitter and bind to your saliva’s protein dehydrating your tongue creating a sandpapery sensation.

Ideal extraction

An ideally extracted coffee is sweet with balanced positive acidity, clarity of flavours (sometimes complex) and a pleasant lingering finish.

What do these descriptors mean?

Sweetness

The sweeter the better, in specialty coffee we are striving for the coffees sweetest potential in extraction. We want to extract as much sugars out of the coffee as possible with reaching over extraction where its masked by negative flavours.

Acidity

Complex and definable acids are what we are striving for, if the acid content resembles a familiar fruitthan you’re getting closer to the ideal, but if you can pinpoint the type of fruit acidity and its variety then you’ve nailed it.

Clarity

If you have over or under extraction with your coffee it will make it hard for you to understand the true flavour profile of the coffee you’re brewing, muddling up the flavours and giving you an unclear understanding of the coffee. You want to be able to taste the coffee and understand its full potential.

Finish

The finish should be long and pleasant.

TDS (Total dissolved solids)

The amount of total dissolved solids in a brewed beverage will alter several things but the two main factors would be your percentage of extraction and the strength of your brewed beverage.

The percentage of total dissolved solids in your brewed coffee means the amount of soluble solids that have dissolved from the actual ground coffee and are dissolved into the brewed coffee.

eg. if your espresso reads of a TDS of 9% that means 9% of that brewed beverage is actual coffee particles and if you have 100g of that espresso and dehydrated it, you will be left with 9g of actual coffee solids.

In order to measure the TDS% of a beverage sample we need to use a refractometer, it is a device that measures the deflection of light as it passes through something. By deflecting the light and measuring how much is being reflected we can measure the amount of solids in a liquid sample in percentage. Once we know the TDS % we can work out the extraction percentage of a brewed coffee.

Percentage of Extraction

Coffee is made up of soluble solids and insoluble solids, so the percentage of extraction determines how much of the coffee (insoluble and soluble) is extracted out of the coffee. The general percentage of extraction that is acceptable in specialty coffee is 18 – 22% (there always can be exceptions though).

To calculate the extraction percentage of your coffee:
once you have your TDS % (reading from the refractometer)
mutilply TDS% x Yield of Beverage (weight of coffee) / divide by dose (amount of dry coffee used) = Percentage of extraction.

Example for espresso: a espresso shot had a TDS of 8.3%, its Dose was 20g, yield was 46g
8.3 (TDS) X 46 (Yield) / 20 (Dose) = 19.09% of extraction.

Means that out of the 20 grams of dry coffee I've used 19.09% of that is in my final brewed beverage. This is to measure how much of the dry coffee we have used up to what percentage.

Example for soft brew coffee:
a pour over brew had a TDS of 1.33%, Dose was 12.5g, yield was 200g

1.33 X 200 / 12.5 = 21.28% of extraction

Knowing the percentage of extraction is a good reference point to understanding how you’re extracting the coffee and to what degree of extraction you’re pushing it to.

 

Extraction is only relevant to flavour, never try to achieve a percentage of extraction without flavour in mind, once you’ve extracted a coffee to a desired flavour profile, then measure extraction to get the reference point.

Strength of Beverage

Simply means the concentration of total dissolved coffee flavours also known as Total dissolved solids (TDS)

To put it simply it refers to the percentage of total brew. Eg. in espressos the strength of coffee generally will be between 7% -12% TDS meaning 88% – 93% of the brewed coffee is water. In filter coffee the strength generally lies between 1.1% – 1.8% TDS meaning 98.2% - 98.9% of the brewed coffee is water.

Coffee is an incredibly intense flavouring agent and to anyone with a trained palate 0.1% of a difference in strength is quite noticeable.

There are two main factors that are influenced by the strength of your beverage, intensity of flavour and tactile of the beverage (weight, body, mouth-feel)

Flavour Intensity

Strength of coffee will alter our perception of flavour, generally the higher the strength of a beverage the harder it is for us to identify the coffees flavour. Even though the same coffee is used, at different strengths our palate will give us different perceived intensities of flavour. Weaker coffees allow us to taste more subtle flavours that are generally missed or masked in higher strength brews. E.g Filter brews can be ten times weaker.

 

Tactile

The texture of a brewed coffee and its mouthfeel are one of the most important attributes to a great tasting coffee. Most consumers expect a certain level of texture, weight and body to their coffee, these do vary significantly depending on location and culture.

Brew Pressure

Pre-infusion

It is the term we use to describe the stage of extraction where water is soaking in dry coffee without really passing through under pressure. This is done in most machines that use flow restrictors or preinfusion chambers.

The water soaks the puck of dry coffee and swelling it in place, trapping fines in place before full brewing pressure hits, the expansion of the coffee cake significantly reduces the chance of channelling as well as it allows the espresso machine to be more forgiving of flawed distribution, tamping or grind setting. Compared to extractions without preinfusion, it tends to produce a slower rate of extraction especially towards the end of the extraction because of fines migration, the fines moving towards the bottom of the basket creates a lot more resistance in extraction.

Common effective preinfusion guidelines 2-3 bars for 5-8 seconds to completely saturate the grounds.

The Ramp Down

The reduction of extraction pressure from the middle to the end of extraction. This is to be believed that the reduction of the brewing pressure towards the end of the extraction process reduces the amount of bitterness and/or harsh flavours associated with the last part of the brewing process as most of the desirable characteristics have been dissolved already, purely this is to add volume to aid in balance of flavours.

The ramp down period is generally 5-20% of the entire brew cycle and usually at a bar pressure of 5-8 bars dependant of the coffee and other variables of course.

 

Graph indicates the ramp down in pressure avoids over extraction and reduces the chance of it from the last stage of the extraction process

Brewing Pressure

The magical brew pressure for espresso has always been set to as 9 bars, as this is the setting (on average) that has proven to be the producing best results. Because of how traditional espresso machines were built the brew pressure had been measured to be at around 9 bars of atmospheric pressure, as the industry progressed in more advanced machinery, the coffee machines based it all around the old school lever machines so they’ve kept it at the same 9 bars.

Because of this, everything we do now in the industry is to aid this eg. how we roast, degree of roast, tamping techniques, distribution etc.

Certain brew pressures have been proven to bring out certain things out of the coffee and different bar pressures work better with different grind particles off different grinders eg. coffees off the EK43 tend to extract better at lower brew pressures around 6-7 bars, however there are too many variables to consider if you’re trying to manipulate bar pressures to create desired flavours and grind particle size is just one of them.

Brew temperature

The temperature of water used to extract espresso is another variable that can lead to a new list of questions from baristas and coffee professionals. Water temperature for brewing espresso will affect the strength of your coffee, flow rate and ultimately taste.

All you need to know about water temperature is that for espresso preparation the average temperature that most specialty coffee establishments use is around 90 – 96 degrees Celsius.

The most commonly used temperature at Code Black is 93 degrees Celsius, the reason for this is because of the coffee we are using, we quality control our coffees at 93C and base it around that temperature. Anything significantly higher or lower than this tends to extract certain negative qualities out of the coffee or promote unbalanced espressos.

Graph indicates that excessive differences in brew temperatures bring out different amounts of elements in coffee that make it positive or negative, this is all dependent on the coffee of course

Lower Temperatures

  • Can be used to overcome the high solubility of over roasted / over developed coffees
  • Decrease extraction yield
  • Decrease body
  • Decrease sweetness
  • Decrease bitterness
  • Increase acidity
  • Decreased espresso flow rate

Higher Temperatures

  • Can compensate for lighter roasted less developed coffees, as it will aid in extracting a more insoluble coffee.
  • Increase extraction yield percentage
  • Increase in body
  • Increase in sweetness
  • Increased bitterness
  • Decrease acidity
  • Increased espresso flow rate

Dial in / troubleshooting

Extractions – Dial In

The only way you can identify problems with extractions are if your extraction techniques are kept at a constant and you are promoting as much “even” extraction as possible eg. even tamping / consistent grind size / even distribution / clean screens / etc

Being able to identify positive and negative flavour attributes from extraction is a very important skill in a good barista, this skill comes with practice in tasting. Tasting the same coffees with different extractions eg.changing the extraction times and/or yields to bring out different flavours will help you understand what changing each variable will do and bring out of the coffee.

Below is an espresso compass to help you identify where are extractions are sitting and pointing out a direction on how you can improve your extraction if it’s not at your desired flavour profile.

Be aware that if you increase your yield you are simultaneously making your coffee weaker and increasing your extraction and if you are decreasing your yield you are increasing the strength and decreasing extraction.

Flavour Breakdown when Tasting Coffee

Check for intensities of the different attributes in coffee when you are tasting to help you identify the problem eg.

 

Once you have pointed out the intensities of each attribute, you are now able to determine whether the brewed coffee is correctly brewed, ideally you want a “balanced” coffee, however some coffees won’t allow you to achieve this so aiming for optimum extraction is the goal.

It can mean aiming for maximum sweetness without dominant bitterness or dryness, with a good strength or mouth feel (not too watery or thin)

OR

achieving a balanced brew where the acidity, sweetness and bitterness all matched, in this case if acidity and sweetness are matched but bitterness is lower than the two that is also a good extraction with a good strength or mouth feel (not too watery or thin)

Using yield to manipulate flavour
When you increase the yield you are increasing the amount of water content of the beverage and increasing extraction. What that will do in terms of changing the flavour intensities is:

 

Using time to manipulate flavour
When you increase the time, you are increasing the contact time of water to the coffee of the beverage and increasing extraction. What that will do in terms of changing the flavour intensities is:

At times and most cases it is required for you to change both yield and time in order to achieve an optimum extraction.

To be able to achieve this successfully you need to understand where the problem is by tasting the coffee and identifying what it lacks or what is has too much of by plotting it on the intenties chart.

Eg. Lets say a coffee at a yield of 48g and a time of 24sec gave us this result on the chart.

 

Because the acidity is so high we can’t just fix it by increasing contact time to bring up the sweetness and bitterness to achieve balance.

First we will need to reduce the acidity by diluting the drink with a larger yield eg. 52g, this would have also made our beverage sweeter and more bitter, reducing the strength and body. This is what it looks like now:

 

Now that these intensities are getting closer to balance, we can use time to balance it out, by increasing the contact time for example from 24 sec to 27sec we will increase the sweetness and bitterness to match the acidity. We don’t want the beverage to get any weaker or have less body than where it is now.

By manipulating the yield and time we are able to balance out the flavours of the coffee where the acidity, sweetness and bitterness are matched and the body of the beverage isn’t too thin.

Improve your extraction:

Distribute grinds evenly and by using a good grinder, flat and snug tamper, VST baskets and a well developed roast.

 

Increase your extraction:

Make it more even or by using a finer grind setting (time increase). Don't grind too finely or extraction will become uneven and decline.

 

When adjusting yield:

Do not change the dose. Time will change as a result. Only adjust grind if your shot time is too far off.

 

A more even (improved) extraction is always desirable because it:

  • creates a larger sweet spot
  • allows for richer and sweeter espresso
  • intensifies positive and unique flavours
  • diminishes negative and generic flavours
  • is more efficient

If you're tasting bitterness and sourness together, your extraction is likely uneven because they can co-exist there. An even extraction has more room for Barista expression and exploration of the coffee's unique flavours without distraction.

Grind Sizes

Extractions with different grinders

Different grinders will have different burr material, burr size, burr shape and grinding speed, all these differences will obviously give you a different grind size and/or shape of coffee grinds. Because of this you will need different extraction recipes

This is a graph that indicates the varied grind sizes of different burrs.

The grinders that produce the largest variance in grind sizes are the blade and basic hand grinders, because of this you won’t be able to achieve even extraction as the different grind paricles will hit optimum extraction at different times.

Conical burr grinders (eg. Robur Electronic Mazzer) and advanced hand grinders still produce a large variance in grind sizes which is the main reason why extractions from these grinders tend to be significantly less than flat burrs, The larger particles will tend to be under extracted and the small finer particles will be over extraction.
On average Conical burrs produce extractions at around 17 – 19%

Flat Burr grinders (eg. Mythos One and the DC One grinders) poduce very consistant grind size particles and allows a large percentage of the total grind particles to hit optimum extraction.
On average Flat burr grinders produce extractions at around 18 – 20%

Vertical Flat Burr grinders (eg. EK 43) produces very consistent grind sizes which allows most of the grind particles to reach the same/ similar extraction point, averaging from 20 – 22%

Latte Art

Milk science and steaming

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:

Fat

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

Sugar

Lactose, made up of galactose and glucose

Protein

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 micro-foam. Once the milk has reached 37 degrees Celsius, it is important not to stretch the milk anymore but still maintain a whirlpool and increasing the milk temperature to 60 – 65 degrees Celsius, 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*

Always start with a milk pitcher around half full of ‘cold milk’ give or take more or less about 20% from the midway point

Start with the steam tip halfway submerged into the milk the steam tip needs to be in-between the centre and the side of the jug, either clockwise (in diagram) or anti-clock wise.

Milk needs to be spinning in a circular motion.

Tip: lock the steam arm into the spout to minimize the amount of movement of the pitcher while steaming.

Milk jugs

Finding the perfect milk jug depends on several factors such as the user’s preference on pouring with a smaller or larger jug or what art are you trying to achieve, as the different shaped spouts will give you a different result. Here’s a quick guide to the different spouts and what art they are better suited for:

Sharp Spouted Jugs are great for finer detailed latte art such as pours that incorporate wiggles, Rosetta’s. They are good for complex patterns that require a lot of elements.

Semi–Sharp Spouted Jugs are great for most patterns and will give you the best of both worlds, fine lines and clean round shapes, good for all the basic pours and med to high complex patterns.

Round Spouted Jugs are great for simple and clean latte art, especially Tulips / Hearts and Dots. promotes consistency and efficiency.

Pouring

Before we pour any milk into the coffee the position of the jugs spout facing the cup is important, as this will determine where the latte art will be facing once poured. (Ideally, we want it to face the customer)

You must pour into the deepest part of the cup to begin any latte art pours as this part is crucial to raise you crema so that you will have a nice canvas of crema to draw onto.

Tip: Swirl your espresso before you pour so that you create an even colouration of crema

The deepest part of the cup is usually where the ridge is.

Depending on how much you tilt your jug forward, it will control the amount of flow of your milk coming out. The harder you tilt forward the more the white will pour on the surface of your coffee.

Sinking the milk is all about pouring the milk into the deepest part of the cup so you can raise you crema to your desired point. Where you want to raise it to depends on your complexity of your pattern, the simpler the art the more you raise the harder the art the less you raise.

Tip: Pour in a left right motion rather than a circular motion to avoid turbulence in your coffee so when it’s time to draw, the movement of the milk won’t warp your art. Keep pouring higher as you’re sinking the milk as the cup fills up your stream of milk is getting shorter.

Floating the milk is the one of the three stages of pouring that we do not want in producing latte art.

This is the in-between height where it’s not poured high enough that we are sinking the milk but not close enough that we are drawing the pattern in this case we get washed out colours that are murky and faded.

Tip: to prevent floating, once the crema is raised stop pouring for a split second and bring the jug as close as possible to the coffee to start the drawing stage.

Drawing is the stage where the jugs spout needs to be as close as possible to the coffee but not actually touching the crema. Generally a few millimetres above the crema.

Depending on the pattern, the point where you start to draw will be different but in most cases, it’s near the lip area closest to the milk jug.

Basic Patterns

“The Dot” aka Monks Head

Fundamental to most building blocks of latte art patterns

“Two Tier’d Tulip”

The next step up from the Dot

“Three Tier’d Tulip”

A classic and is built from the dot but repeated three times

 

The following two patterns require a “wiggle” technique where you’re only moving the jug slightly with your wrist to creating a left right flow of the milk.

 “Wiggled Heart”

A classic and very commonly poured. This is the building block to doing Rosetta’s

“Rosetta”

A classic and the most difficult to achieve, but when done right its very visually effective.

Barista Guides

Espresso basics

PULLING A SHOT

  1. Remove the portafilter
  2. Purge the group head with a small amount of water, this gets rid of any coffee grinds or oils sitting on the shower screen
  3. Knock out the previous coffee puck sitting in the basket
  4. Wipe out the basket with a clean, dry towel
  5. Grind and dose the coffee
  6. Distribute the grinds evenly in the basket
  7. Tamp evenly
  8. Wipe the rim of the filter basket and edges of the portafilter to remove any free coffee grinds
  9. Insert the portafilter into the grouphead and brew.
  10. Remember to keep the coffee evenly distributed in the basket and to tamp evenly with a straight arm.

WHAT’S EXTRACTION?

When hot water comes in contact with ground coffee it begins what’s called extraction. This is the process of extracting flavour compounds from the dry coffee and dissolving them into hot water. All coffee beverages are part water, part dissolved coffee.

CONTROLLING FLAVOUR

When dialling in it's best to start with a dose that will always remain the same. Then get the type of flavour right by balancing under & over extraction through manipulating your yield. Then work on getting the desired intensity of flavour by grinding finer or coarser to manipulate your contact time.

Milk basics

THE SCIENCE

Milk contains a number of different vitamins, minerals and proteins but we will be looking at the three main things that will matter to how we use it on an espresso bar:

  • Lactose
  • Fats
  • Proteins

Lactose
Lactose is responsible for the sweet and pleasant taste we find in milk, it is a solution made of sugars that is mixed into the liquid. The more we increase the temperature of the milk the more we dissolve the lactose, therefore increasing the perceived sweetness. If heated higher than around 60ºc, however, milk begins to lose it’s sweetness.

Fats
The percentage of fats that milk contains can range from 0% - 4%. Higher fats increase the body or fullness of the flavour of the milk, making for a more pleasant texture.

Proteins
Proteins are responsible for making milk foam the way it does and are very complex structures. These give stability to the air bubbles that we incorporate when steaming a jug of milk, allowing them to maintain their shape and become ‘micro-foam.’ At temperatures higher than around 60ºc the proteins begin to denature and lose stability, no longer maintaining the silky and creamy result we want.

STEAMING MILK

Step One:
Start with cold milk and a cold jug. Starting at a low temperature gives you more time to texture the milk. When pouring milk into the jug, it should come to the bottom of the spout - too much milk will risk overflowing and spilling, and not enough will be too hard to steam properly.

Step Two:
Wrap a clean cloth around the steam tip and purge for two seconds, removing any condensation left in the steam wand.

Step Three:
Submerge the steam wand with the tip just under the surface. Activate the steam pressure then slowly and precisely lower the jug to introduce air into to milk - this will sound like a slight crackling noise. Make sure it’s controlled and you aren’t letting any big gulps of air. The depth of the steam wand will determine how much foam is created on the top of the milk (i.e. Cappuccino vs Flat White). Deeper will be thinner milk, shallower will be thicker.

Step Four:
Make sure the milk is spinning like a whirlpool - this is called ‘texturing’ the milk and is how we make it silky. The easiest way to do this is to adjust the point at which the steam wand enters the jug (see diagrams). If it’s closer to the centre line, it will spin slower. If it’s further away, it will spin faster. The angle of the steam wand will also affect this.

Step Five:
When the jug becomes an uncomfortable temperature and is too hot to hold, turn off the steam pressure and lower the jug.

Step Six:
Wipe the steam tip thoroughly with a clean cloth and purge the steam wand again for two seconds, removing any milk residue.

Step Seven:
Swirl to remove any larger bubbles. If you tap the jug gently on the bench you'll compromise 'microfoam' integrity. The more you turn the jug the more elastic & shinny the milk.

If all these steps were followed correctly, your milk should:

  • Be between 55ºc - 65ºc in temperature.
  • Appear smooth, glossy and without any bubbles on the top.
  • Have increased volume by 20% - 40% depending on type of drink (latte, cappuccino etc.).


TROUBLE SHOOTING

POURING THE MILK
When pouring the milk it’s important to preserve the crema on the top as it’s responsible for that initial flavour that we taste when drinking a milk coffee and can influence the perceived ‘milkiness’ of the drink. We use two variables to control this: flow rate and the velocity of the fall of the milk, which is controlled by height of the jug from the cup. By limiting the flow rate we can limit the dissipation of the textured milk on top of the crema. By controlling the velocity we can push any textured milk that’s settled under the crema, enabling us to create that nice brown colour.

Filter basics

Dialing in filter coffee is surprisingly similar to espresso, but there are a few significant differences that are super important to understand.

Just like espresso we have three main variables that we use to control the flavour of our filter brew:

Dose
Dose is the weight of the ground coffee on a set of scales. This should remain as constant as possible to eliminate extra variables from affecting the flavour of the coffee. Your dose will affect is how much coffee you start with - For this reason it’s much easier to just decide on a dose and alter the amount of brew water you use to create a bigger or smaller beverage. If you have a set recipe and underdose or overdose, you will over-extract or underextract the coffee.

Brew Water Weight
This refers to the amount of water that you use to brew your coffee with. This is usually measured with the brewing apparatus and decanter sitting on a set of scales. This will determine the type of flavour you extract and is the most important variable to change when making filter coffee. Lower volumes will taste ‘Under-extracted’ which often tastes sour, salty and rich. Higher volumes will taste ‘Over-extracted’ which often tastes bitter, woody, dry or watery.

Brew Time
This is the amount of time the coffee takes to brew. You can control this variable by changing your grind-size, or pouring technique. Brew Time mainly determines the concentration or strength of flavour you extract. Higher Brew Times will result in richer, more concentrated, bigger body shots. Lower Brew Times will result in lighter, more balanced, less concentrated shots. Higher or lower Brew Times will also play a part in making your coffee taste over or under extracted, but not as much as Brew Water Weight.

BREWING DEVICES

Different brewing devices will behave differently. We can separate brewing devices into three categories - Flat Bed, Cone Shaped & Immersion.

Flat Bed
Flat bed brewing devices such as the Kalita’s are easiest to control with using multiple small volume pulses with your kettle. Flat Bed brewers almost always take approximately 30 seconds longer than cone shaped brewers to complete. We recommend a recipe of: 12g coffee, 200-210ml water & 3:00-4:00 brew time.

Cone Shaped
Brewing devices such as the Hario V60 work best using three or four pours of a consistent volume. Agitating the bloom with a spoon will aid with extraction. We recommend a recipe of: 12g coffee, 200-210ml water & 2:30 - 3:00 brew time.

Immersion
Immersion brewers such as an Aeropress are the easiest brewing devices to use. We recommend grinding slightly finer than other devices and steeping for a much longer time as these brewers don’t use gravity to aid in extraction. We recommend a recipe of: 12g coffee, 200-210ml water & 4:00-5:00 brew time.

COMMON ISSUES

Brew too weak
If your resulting brew is too weak or watery it could mean one of two things: the brew time was too short or the grind was too coarse. Try first extending your brew time, if that doesn’t fix the issue then grind finer until the brew tastes less watery.

Brew too strong/rich
If the brew is too rich or strong then grinding coarser or brewing for a shorter period of time should easily fix the issue.

Tastes sour/muddled
This taste is usually caused by under-extraction. If this is the case try using more water, grinding finer or increasing your brew time.

Tastes dry, bitter or 'dirty'
Usually caused by over-extraction. Try using less water, grinding coarser or decreasing your brew time.

Flow of water 'choking'
This is an issue unique to flat-bed and some cone-shaped brewing devices. If this is a consistent problem it may indicate that you need to grind your coffee coarser or pour in smaller, more frequent pulses to make the force of gravity more constant, thereby increasing flow-rate.

Refractometry

REFRACTOMETRY

Coffee is made up of one part water and one part dissolved organic coffee material. We can measure the amount of this dissolved coffee material by using a refractometer. This tool works by measuring the refraction of light through a liquid.

The angle that the light bends at determines this measurement and is given to us by the refractometer as a percentage of Total Dissolved Solids (TDS%). This number tells us how much of the brew is made from dissolved coffee material. In other words it tells us the strength or concentration of flavour in a coffee beverage, meaning that higher TDS% can taste rich or intense, whereas lower TDS% can taste weak and watery.

 

OPERATING THE REFRACTOMETER

  • Wipe the lens with a medi­swab.
  • Give the coffee a really good stir so as to evenly distribute the dissolved material throughout the brew.
  • Take a sample of the espresso at room temperature. This is important as compounds in hot liquid will vibrate faster and harder than in cool liquid, making the reading inaccurate.
  • Place a syringe filter on the end of the syringe. This filters out any undissolved particles which could interfere with the reading. This step is only required for espresso readings.
  • Cycle through the options until you reach ‘Espresso’ or ‘Coffee’ and press ‘Go’
  • A number should come up on the screen after a little while. Keep pressing ‘Go’ until the number stays consistent.
  • You now have an accurate measurement of the TDS% of the espresso!
  • Wipe the lens with a clean towel and then with a medi­swab.

We can use this reading in conjunction with a complex formula to tell us how much soluble mass we’ve extracted from the dry coffee, given as Extraction Yield (EXT%). In other words this is the percentage of coffee ‘stuff’ we’ve taken out of our coffee bed. Too much and we get an over­extracted coffee, not enough and we get under­extracted coffee.

For ease of use, we have a tool that works the formula out for us that we can download onto our phones called VST Coffee Tools (available on the App Store or Google Play Store). This app also calculates things such as how much liquid is retained in the coffee bed & different brew methods used.

CONTROLLING THE NUMBERS

We can control TDS% & EXT% by focusing on three main things: Dose Weight, Beverage Weight/Brew Water Volume & Contact­Time.

Dose Weight
This will affect the amount of raw material we have to work with and will make it easier or harder to get a higher TDS%. Higher weights mean higher TDS% are easier to achieve but can be extremely wasteful and often just result in a bigger beverage.

Beverage Weight (BEV) also known as Yield Weight & Brew Water Weight (BW)
This will either mean more or less water has been used to brew with. This will impact EXT% dramatically and is a very important variable. Higher numbers mean more water has passed through the coffee and therefore we have taken more solubles out. By using more water though, our brew will become diluted and our TDS% will go down because there’s more water and less dissolved coffee. This is why it’s important to keep a balance between EXT% & TDS% so as to have a sweet, balanced coffee but retain a pleasing mouthfeel & body.

Contact­ Time
This influences both EXT% & TDS%, but most noticeably influencing TDS%. The longer that water is in contact with coffee the more material is dissolved in the cup, bringing our TDS% up and also indicating that we’ve extracted more solubles. Higher contact times can be utilized to increase the TDS% of a brew. We can control this by making our grind finer or coarser.

When dialin­g in with a refractometer it can be easy to arrive at a reading that worked previously without tasting the coffee, but it’s very important to always taste first and use the refractometer second to give us objective information as to why our coffee tastes a certain way and what we can do to improve it.

Processing

After the cherries are harvested from the coffee trees, they’re taken to a processing facility of some kind. Through any type of processing coffee must go from 65% moisture down to 9-12% moisture without any negative qualities being imparted (i.e. mould, rot, etc). Below are the main ways of doing this along with some insight into how each process impacts cup. Coffee Is processes in the following ways:

Natural

The oldest and simplest processing method available because it’s demand on technology & resources is minimal. Being that coffee is grown in mostly developing nations it’s often adopted where water is to precious to waste or of to poorer quality to be used. Coffee is received to the patios and undergoes an optional flotation (rinse) to remove foreign matter. After this the coffee is taken to one of a few types of drying facilities, most commonly:

  • Patio: Concrete or clay patios, on which the coffee is placed and turned frequently to ensure even drying as airflow to lower layers is minimal to none.
  • Drying beds: Frames of wood with mesh screens to suspend the coffee of the floor, allowing greater circulation of air during drying.

Held together by the skin each cherry as it dries is a closed fermentation tank, the fermentation of sugars and alcohols creates very distinct cup profiles:

  • fermented sugars (syrupy sweetness)
  • thick body
  • wild and intense fruit qualities.
As this is such a ‘natural’ system (minimal input from humans) care must be taken when selecting naturally processed coffees as ferment can quickly turn to rot. Strict green analysis and vigorous cupping is a must when looking to purchase.

Washed

Washed processing is largely responsible for the greater clarity we now expect from Specialty Coffee. In this process it is of utmost importance that all mucilage (cherry flesh) is removed to maintain absolute clarity of cup and ensure no rot/mold can develop. While this would have initially been done very primitively (squeezed off by hand), the majority of farmers now use depulpers that, if carefully tuned, accurately remove majority of the flesh and skin leaving the parchment coffee.

Then all washed coffee must go through fermentation. This can happen a number of ways and with various quantities of water (or none). Natural yeasts and bacteria eat away the remaining mucilage in a process not dissimilar to the fermentation that happens during beer brewing. Depending on the amount of remaining mucilage, weather, temperature, and humidity fermentation ranges from 6 to 72 hours with varying impact to cup profile. After this all the parchment coffee is removed a washed through tracks of water and taken to be dried.

It’s through this fermentation and washing process that this coffee exhibits:

  • clarity of terroir (all aspects of coffees growth)
  • balance
  • crisp acidity
  • cleanliness.

When buying washed coffee it’s these components we look for first, and prize so highly.

SEMI WASHED/PULPED NATURAL

Similar to washed, semi washed is depulped, removing cherry skin and varying degrees of flesh (mucilage) but from here it changes. Instead of undergoing fermentation* the parchment coffee with mucilage is placed straight on the drying patio/beds.

Drying of Semi washed coffee can be a scary prospect. The fermenting sugars can quickly turn moldy without the skin of the cherry as protection. Farmers processing this way must pay close attention during drying, as one mold could mean an entire crop lost. The coffee is laid out and raked constantly to ensure even air flow until fully dried. The parchment coffee of the semi washed process has a brown/reddish (honey) colour due to the natural caramelisation of sugars (looks like praline).

A well processed Semi washed should exhibit a blend of natural and washed processing:

  • Intense sugary sweetness (natural)
  • Heavier body, (natural)
  • Crisper acidity (washed
  • Clean cup (washed)

A lot of risk is taken when processing this way so it’s less common. Countries like Brazil, Costa Rica and Bolivia are amongst the few who risk the process but deliver high quality due to their attention to detail throughout the whole process.

Some coffee does go through fermentation, but not for long enough to remove mucilage. This fermentation acts as a stimuli for the breakdown of sugars.

Honey

+++

KENYAN PREP.

Classified as fully washed Kenyan prep is actually a little different so deserves its own name.

Kenyan Coffee Factories require coffee to be sorted by farmer to remove under/over ripes & visible defects. Once sorted the coffee is pulped to remove most if not all the mucilage. The standard pulper used in Kenyan Factories(McKinnon) uses floatation to separate density into different channels. Water is drained off and usually recycled once, the coffee is dry fermented (aerobic fermentation) for 12-24hours to loosen the remaining mucilage.

After fermentation the coffee is washed to remove the loose mucilage and any remaining fermentables along with the yeast responsible. Soaking/Secondary Fermentation takes place to ensure all fermentation has or can take place. This usually requires another 12-24hours. The coffee is rinsed then for a final time and dried Slowly over 2- 3 weeks where the moisture content is reduced to 9-12%.

Wet Hulled

+++


As we all know fermentation (when done correctly) can yield some extremely unique flavours in coffee. Today there are many different forms of controlled or experimental processing. As most of these techniques are fairly modern we are still learning the science behind the method. But by controlling the rate the sugars break down in the processing of coffee you can achieve more intense flavours, mouth feel, and overall cup quality.

These methods can be controlled in many ways, for example having the coffee's placed in anaerobic conditions allowing the sugars to break down slower to increase certain flavours in the cup. Or by the introduction of certain acids, or bacteria in the fermentation process. For example: lactic fermentation.

Lactic fermentation allows for the growth of lactic acid bacteria under anaerobic conditions with constant measurement of oxygen level, sugar content, and pH levels. The bacteria feed on the sugars in the mucilage, generating a high concentration of lactic acid that impacts the coffee's flavour profile, this will increase the coffee's body giving it a more "creamy" mouth feel. After reaching the desired pH levels, the coffee's are then soaked in clean water to stop the growth of bacteria, washed, and dried on raised beds.

Brew Guides

Pourover

V60 / Kalita

SERVES: 1
COFFEE: 12g
WATER: 200ml at 93 - 96° (Just off the boil) 

  1. Place the paper filter into the cone and rinse with hot water to wash out any paper flavour. This will also pre-heat the cone.
  2. Place V60 or Kalita and cup on scales.
  3. Bring filtered water to a boil and let it sit until it reaches temperature range.
  4. Add ground coffee to cone and settle for an even coffee bed. Your grind should be Medium grind size. Tare scales.
  5. Pour in enough water to just cover coffee grinds (approx 30g) and stir gentle to ensure all coffee is saturated. Start timer.
  6. Wait 30s and add another 100g of water. Once the water has almost completely drained through, add remainder of water.
  7. Decant and serve. Brew time 2:30 minutes

Plunger / French press

SERVES: 2 - 3
COFFEE: 30g
WATER: 500ml at 93 - 96° (Just off the boil)

  1. Bring filtered water to boil and let it sit until it cools to temperature range.
  2. Pre-heat plunger by rinsing with hot water.
  3. Add ground coffee to plunger. Your grind should be coarse, larger than sand granules.
  4. Pour 500ml of water into plunger. Try to ensure that all grounds are wet.
  5. Attach plunger lid to retain heat but do not push down. Leave to brew for 3:00 minutes.
  6. Remove lid and gently stir 3 times to unsettle the grinds.
  7. Attach lid, slowly plunge and serve. Total brew time 4:00 – 5:00 minutes.
Tip: 60g of coffee to 1L of water is the recommended brew ratio, depending on the size of your plunger.

Chemex

SERVES: 2 – 3
COFFEE: 36g
WATER: 600ml at 93 - 96° (Just off the boil)

  1. Fold and place the paper filter onto the Chemex. Rinse with hot water to wash out any paper flavour. This will also pre-heat the vessel.
  2. Empty the preheating water. Place Chemex on scales.
  3. Bring filtered water to a boil and let it sit until it reaches temperature range.
  4. Add ground coffee to paper cone and settle for an even coffee bed. Your grind should be at a Medium to Coarse grind size. Tare scales.
  5. Pour in enough water to just cover coffee grinds (approx 100g) and stir gentle to ensure all coffee is saturated. Start timer.
  6. Wait 30s and add another 250g of water with a thin stream of water, circling the ground coffee starting from the centre circling outwards. Once the water has almost completely drained through, add remainder of water.
  7. Swirl and serve. Brew time 3:30 minutes

Aeropress

SERVES: 1
COFFEE: 16g
WATER: 250ml at 93 - 96° (Just off the boil)

  1. Start with aeropress upside down (inverted).
  2. Bring filtered water to a boil and let it sit until it cools to temperature range.
  3. Rinse filter to wash out any paper flavour. Place into round lid and set aside. Preheat aeropress with hot water at the same time.
  4. Add ground coffee to aeropress chamber. Your grind size should be medium to medium fine. Place on scales and tare.
  5. Start timer and add 250ml of water, filling to the top of the aeropress, gently stir. Attach lid and let it brew for 2:30 minutes.
  6. Place cup / jug upside down over the top of the aeropress and carefully flip over so the cup is on the bottom and aeropress sitting on top. *BE CAREFUL*
  7. Slowly press out into your jug / cup and serve. Brew time 3:00 minutes.