Barista
What you need to know before you begin:
The very basics of coffee are presented in this course. This is the very minimum to start on the path of becoming a coffee professional rather than the “guy who makes our coffee”. Welcome to the world of the Barista!
Where did this thing come from?
What is it?
The word “coffee” seems to have entered English in 1598 via Italian caffè. This word was in turn created via the Turkish kahve, which in turn came into being via the Arabic qahwa. This last is a word is of uncertain etymology, and can mean both “coffee” and “wine”.
There are many legends around the origin of coffee as a drink. The usual myths attribute the discovery of coffee either to an Ethiopian goat herder generally considered to be named Kaldi, or the Yemenite Sufi mystic Shaikh ash-Shadhili, a traveler in Ethiopia, they are both said to have observed goats unusually aroused! They are then said to have tried the berries that the goats had been eating, and experienced the same vitality.
One often cited source of origin of both the drink and the name is the Kingdom of Kaffa in Ethiopia, where the coffee plant is said to have originated (the Ethiopian name curiously is bunn or bunna).
Coffee is grown in the Tropics.
The common coffee tree (Coffea arabica) is a flowering evergreen shrub indigenous to the Kaffa region in Ethiopia. It produces the Arabica coffee bean. Other species of the coffee plant, include C. liberica C. esliaca and C. robusta, (or Coffea Canephora the coffee beans known as Robusta) have been discovered growing wild in various regions of Africa.
About the varietals grown:
Arabica, is typically hard to grow, this means that the trees require care to produce good results. Different lines stains and hybrids of Arabica are grown. These different strains produce differing flavours in the beans.
Robusta is easy to grow. It contains roughly triple the caffeine of Arabicas. Caffeine is a natural insecticide. The result is that lazy farmers typically farm and produce bad quality Robusta. This does not mean that Robustas are intrinsically bad
While they are not actually separate varieties of coffee bean, among the unusual and very expensive robustas are the Indonesian Kopi Luwak and the Philippine Kape Alamid. These beans are actually collected from the recovered droppings of the Common Palm Civet, whose digestive processes “pulp” the coffee and give it a distinctive flavour!
Liberica & esliaca, the other varieties, are not grown much.
Interesting Coffee facts:
Each day, 2 out of 3 people drink coffee world wide
2.5 Billion cups of coffee are drunk per day.
Finland & Sweden drink the most coffee per capita, 5 cups per day per person!
Coffee is generally considered the second most traded commodity after oil.
Origins
What do we want from a great coffee? Strong or weak? full flavoured? Bitter? Is bitter the same as strong?
My personal goal is to have coffee deliver the taste that the aroma of freshly ground coffee promises. And no, bitter coffee is NOT strong coffee! Why don’t we serve sugar as a dessert, sweet tasting enough, it should meet our dessert needs? It lacks complexity. We need the same concept of complexity from our coffee. We want a variety of interesting flavours and mouthfeel.
Different terroir’s (growing conditions and locations aka territories), make different flavours available to the coffees. Altitude, soils, macro & micro climates, are all location specific factors altering the characteristics of the coffee.
Storage conditions, roasting techniques, age of beans, freshness after roast and preparation techniques and conditions will all have dramatic effects on coffee character, or lack thereof.
Farming
Different skill and care levels will drastically alter the quality & flavours of the coffees.
Are they shade grown? Do they prune or cut back? Do they irrigate? Do they only pick ripe cherries?
The solutions to these questions will determine characteristics in the taste of the end product.
Processing
Were the coffees wet processed or natural, find out how this affects flavour. Were the best beans selected? Were defects removed? Again these issues will determine the character & quality of the coffee
Selecting
How does one choose the best beans? Would you go by their gradings? Not a chance. Most gradings are a reflection of the appearance of the beans. The only way is to sample roast high quality samples and cup and taste them in order to assess flavour. One also needs to develop a relationship with the farmer. Of course one must pay the farmer a premium for better beans. It goes without saying, that if the farmer is rewarded for better quality he will be motivated to produce better quality. More effort, and better selection with better methods will produce better results. We believe that Relationship Coffee, coffee bought and sourced from farmers via a direct relationship will usually be best[A1] .
Roasting
Before the coffee is roasted, it is estimated that 260 pairs of hands touched each bean. The bean was as good as it can ever be once picked from the tree. Our only opportunity is not to ruin it. We, as roasters and Baristas, have a responsibility to not ruin the efforts of those before us.
How dark roasted and why?
Please stop reading for a moment to consider this: Is a dark roasted coffee stronger? Is a light roast weaker?
In answer: No! As the beans are roasted, the over 1400 volatiles in the coffee will be developed and matured and if roasted long enough, burned off and made bitter through various processes. The Green bean is almost flavourless, reminiscent of very hard uncooked pasta. As the Coffee is heated in the roasting process these individual volatiles develop flavours through the Mallard processes. As soon as the flavour reaches its individual maximum, further heat will “burn” the flavour off. Eventually if taken to a high enough temperature the Pyrolitic processes will begin, burning the volatile and producing a burnt, bitter flavour or charcoal. To put all of this into simple terms, in order to produce the maximum peak of all the flavours one has to find where the best flavours are maximised together! Sound difficult? That is because it is! The only way to do this is to roast a given coffee in different ways, take meticulous notes and roast more like the way that tastes best!
Is bitter strong?
Overwhelming bitterness in Coffee is bad, but so common. Low levels of bitterness help balance coffee flavour and can tame acidity while adding another dimension. Because we are so sensitive to bitterness, high levels will overwhelm our tastebuds. The theory is that this was part of our evolutionary process. In our evolutionary ventures we seem to have rightly associated bitterness with poisons and we are overly sensitive to it, especially when young.
Bitter coffee flavour is from compounds reacting with the circumvallate papillae at the back of our tongue. Astringency, the dry taste is caused by compounds that can precipitate salivary proteins on the tongue. Astringency and strength especially in neat espresso are often confused with bitterness
Causes:
overextraction.
Too many dissolved coffee solids. Coffee just made too strong.
Water Hardness, coffee made from water that is either too soft or hard may taste bitter
Making coffee VERY hot will MASK bitterness.
Caffeine can taste bitter
Over-roasting, burnt pyrolitic flavours are bitter
How long were they roasted for and why?
Ever made fudge or toffee? If you have, you would know that too much heat, too fast, will result in the sugar burning and turning to carbon. Too little will result in nothing happening! In order to caramelise the sugar, you need to get it just right. Coffee is the same. Too much heat will create burnt bitterness and too little will create a woody “baked” flavour. More complication for the artisan roaster, we need to balance the speed too!
Coffee roasting is a chemical process. It causes, through heat and time for the aromatics, acids, and other flavour components to be in turn developed enhanced, melted away and then ultimately burned by the roaster.
Roasting Coffee Beans
Coffee roasting is initially endothermic (the coffee beans take on external heat). The green beans are slowly dried and become a yellow while the beans begin to smell like toast or popcorn.
The second step where the bean pops like popcorn, often called the first crack or pop, happens around 200°C . they double in size, turn cinnamon colour, lose about 5% weight.
between 200 °C and roughly 220 °C, the beans go from cinnamon brown to medium brown and lose another 13% in weight roughly. The chemical process called pyrolysis occurs and is characterized by a change in the chemical composition of the bean as well as a release of CO2.
As the beans approach second crack or pop they become exothermic (they give off heat) This continued pyrolysis occurs between 225-230°C, and the coffee becomes dark brown The is much quicker sounding and the beans take on an oily sheen in second pop. going well into second pop causes the volatile aromatic compounds to melt or burn off and the oils drawing to the outside of the coffee bean are more easily oxidized.
Sadly, many roasters continue burning their beans until a flavourless dark black, shiny bean surface is produced at a final temperature of around 240°C. This is probably done in an attempt to hide poor flavourless beans and cover up dirty machines or even, maybe, stale coffee.
How do We Taste?
We only taste a few things on our tongue:
Sweet: at the front or tip of the tongue
Acidity: down the sides of the tongue
Bitter: Back of tongue, also incidentally on the palette and back of throat
Sour: in the middle, towards the back, in front of bitter
Salt: near the middle front of tongue, behind sweet.
Umami: the Japanese consider this the other flavour and is the “moreishness” we get from things like MSG and has no specific spot on the tongue.
Sour is not to be confused with acid, Acid is not PH but the watering effect on the side of the tongue. Acidity is considered desirable in speciality coffees. We must also note complexity, body and aftertaste when considering flavour.
Complexity: Is the flavour 1 dimensional or complex?
Body: how is the mouthfeel? Full or light?
Aftertaste: lingering or short, pleasant or unpleasant?
Overall: did I enjoy that? Most important of all!
It is good to not allow habit to overawe judgement. Often we appreciate more what we are used to rather than what we prefer. It is worth considering this when evaluating coffees.
Coffee Aroma
Beyond the few tongue tastes listed above, our sensory perception of coffee is predominantly aroma, or smell. sweet, salt, bitter, umani and sour taste attributes that are perceived by the tongue. It is not unfair to thus consider aroma vital to speciality coffee.
Perception of Coffee Aroma
Coffee aroma is perceived by two different mechanisms. It can either be sensed nasally via smelling the coffee through the nose or retronasally. Retronasal perception occurs when the coffee is either present in the mouth or has been swallowed and aromatic volatile compounds drift upward into the nasal passage.
The number of aromatic compounds found in coffee increases every year. Today the number is well over 800, and as our analytical methods become more precise, more will be uncovered. Yet, the perception of coffee aroma is dependent upon both the concentration of the compound and its odor threshold. With that said, understanding coffee aroma is not as difficult as understanding how over 800 coffee elements interact with the olfactory epithelium. It is probable that a relatively small group of compounds that share both a high concentration and a low odor threshold make up the fragrance we know as coffee aroma. This article will discuss the recent research that has narrowed in on these aroma impact compounds.
Illy listed the following chemical processses that affect the development of volatile compounds in coffee (112):
1) Maillard or non-enzymatic browning reaction between nitrogen containing substances, amino acids, proteins, as well as trigonelline, serotonine, and carbohydrates, hydroxy-acids and phenols on the other.
2) Strecker degradation.
3) Degradation of individual amino acids, particularly, sulfur amino acids, hydroxy amino acids, and proline.
4) Degradation of trigonelline.
5) Degradation of sugar.
6) Degradation of phenolic acids, particularly the quinic acid moiety.
7) Minor lipid degradation. 
Interaction between intermediate decomposition products.
In a review article published by Clarke, he asserts that various research groups have identified 150 aliphatic compounds including 56 carbonyl compounds and 9 sulfur containing compounds; 20 alicyclic compounds, including 10 ketones; 60 aromatic benzenoid compounds, including 16 phenols; 300 heterocyclic compounds, including 74 furans, 10 hydrofurans, 37 pyrroles, 9 pyridines, 2 quinolines, 70 pyrazines, 10 quinoxalines, 3 indoles, 23 thiophens, 3 thiophenones, 28 thiazoles, and 28 oxazoles (34).
Table 1 shows the compounds that are likely to be the most influential in coffee aroma This data was compiled from the work of both Grosch and Blank and is by no means exhaustive. It should be noted that the OAV alone does not dictate which compounds are the most important compounds present in coffee, but rather suggests compounds that are likely to have a large impact on the aroma of coffee. The furans are found to be the most predominant group of compounds amongst the coffee aromatics. They typically have caramel-like odors since they result from the pyrolysis of sugars. Shibamoto claims that furans produce key aroma notes when secondary reactions take place with sulfur containing compounds (77).
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Table 1. Important aromatic compounds in coffee as summarized by Grosch. Click on compound name for more information. |
|
Volatile1 |
Conc. (mg/L)1 |
OAV1 |
Coffee Aroma Description2 |
| (E)-ß-Damascenone | 1.95×10-1 | 2.60×105 |
honey-like, fruity |
| 2-Furfurylthiol | 1.08 | 1.10×105 |
roasty (coffee) |
| 3-Mercapto- 3-methylbutylformate | 1.30×10-1 | 3.70×104 |
catty, roasty |
| 3-Methyl-2-buten-1-thiol | 8.20×10-3 | 2.70×104 |
amine-like |
| 2-Isobutyl-3-methoxypyrazine | 8.30×10-2 | 1.70×104 |
earthy |
| 5-Ethyl-4-hydroxy- 2-methyl-3(2H)-furanone | 1.73×101 | 1.50×104 |
|
| Guaiacol | 4.20 | 1.10×104 |
phenolic, spicy |
| 2,3-Butanedione (diacetyl) | 5.08×101 | 3.40×103 |
buttery |
| 4-Vinylguaiacol | 6.48×101 | 3.20×103 |
spicy |
| 2,3-Pentanedione | 3.96×101 | 1.30×103 |
buttery |
| Methional | 2.40×10-1 | 1.20×103 |
potato-like, sweet |
| 2-Isopropyl-3-methoxypyrazine | 3.30×10-3 | 8.30×102 |
earthy, roasty |
| Vanillin | 4.80 | 1.90×102 |
vanilla |
| 4-Hydroxy-2,5-dimethyl- 3(2H)-furanone (Furaneol) | 1.09×102 | 1.70×103 |
caramel-like |
| 2-Ethyl-3,5-dimethylpyrazine | 3.30×10-1 | 1.70×102 |
earthy, roasty |
| 2,3-Diethyl-5-methylpyrazine | 9.50×10-2 | 1.00×102 |
earthy, roasty |
| 3-Hydroxy-4,5-dimethyl- 2(5H)-furanone (Sotolon) | 1.47 | 7.50×101 |
seasoning-like |
| 4-Ethylguaiacol | 1.63 | 3.00×101 |
spicy |
| 5-Ethyl-3-hydroxy-4-methyl- 2(5H)-furanone (Abhexon) | 1.60×10-1 | 2.00×101 |
seasoning-like |
| Table References
1) Grosch, 151. 2) Blank et al., 124. |
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The pyrazines are the second most abundant class of aromatic compounds and contribute to the roasted, walnut, cereal, cracker, or toast-like flavors in coffee. Along with thiazoles, the pyrazines have the lowest odor threshold and therefore significantly contribute to the coffee aroma. Next, the pyrroles are responsible for some of the sweet, caramel-like, and mushroom-like aromas in coffee. Conversely, the thiophens are known to have a meaty aroma and are thought to be produced from Maillard reactions between sulfur containing amino acids and sugars. Thiazoles have an even smaller presence in the overall aroma and are said to be formed via sugar degradation.
Definitions:
Odor threshold – minimum detectable quantity via nasal perception.
Taste threshold – minimum detectable quantity via retronasal perception.
Odor Activity Value (OAV) – ratio of the concentration of a molecule to its odor threshold.
Flavor dilution factor – when high signifies a key odorant.
Decaffeinating:
Caffeine for the soft drink and medical industries is from coffee. This was the initial motivation to produce decaff!
Older Methods:
MC Process, Methylene Chloride, or chemical process. Ethyl acetate is also used. Would you like to taste these chemicals? Neither would we.
The Swiss Water Process, invented in Switzerland in the 1930’s. Much Better!
Better still, Origin uses the CO2 Process:
The Green Coffee beans are put into high pressure tanks and soaked in liquid CO2. This strips out the caffeine and some of the flavour. The liquid is then evaporated leaving crystals of caffeine & flavour mix. These are then spun in a centrifuge, separating the crystals of caffeine from the flavour crystals. The flavour is then washed back through the beans using liquid CO2 again. The CO2 is then allowed to evaporate leaving us full flavoured decaff.
How long will this last?
Freshness
Coffee is ruined by oxidation[A2] . This occurs through exposure to air and moisture
Green, Un-roasted beans are fresh for months and sometimes years.
After being roasted, beans are only at their peak for two weeks or so.
Grind the beans and you’ve got four minutes to work with them.
You know that wonderful aroma of freshly ground coffee? Well that lovely aroma is the flavour leaving the building! Well try vacuum pack them and see how fast that flavour can disappear… ? !
Where do I put my……
Basic Storage
What do you do with those amazing, fresh beans that were roasted just for you? Well, mixing them with air and having them absorb water or sucking the aroma out of them by vacuuming are probably the best ways to ruin that freshness.
So what to do, what to do: Easier to tell you what not to do!
Don’t store them in the fridge or freezer!
Don’t Vacuum pack them!
Don’t grind them before you need them!
Do store them in a dry air tight container, in a cool dark place.
