Parabolic | DRYING
Many drying environments can be used to dry coffee beans once they have been harvested. Parabolic drying takes place inside an environment much like a greenhouse or polytunnel. As with all drying and processing techniques, it appears that parabolic drying is a multifaceted equation – the coming together of a number of variables defines the results. Parabolic drying, like mechanical drying, is most popular in countries with erratic rainfall. The polytunnel helps create a more controlled drying environment.
SEE ALSO
Mechanical drying p145
Raised beds p186
Past crop | OLD COFFEE
It is usually considered that fresh-crop coffee tastes better, though exactly when a coffee becomes “past crop” is not clearly defined, and a market does exist for some purposely aged coffees – Monsoon Malabar and Old Brown Java are good examples. Interestingly, a freshly harvested coffee can taste a little grassy, tight, and green, and so, while fresh is the rule, optimal flavour often requires some resting as well (much the same applies to freshly roasted coffee). Coffee from origins that struggle with drying will fade and taste like past crop more quickly. The widespread adoption of GrainPro Cocoons – plastic storage bags for green coffee – has prolonged the life and quality of coffee beyond what used to be possible. Even so, once imported, the environment in which green coffee is stored has a big impact on the speed of ageing. Heat and variable humidity are a problem. Regardless of how engaging and beautiful it is to have a roaster in the coffee shop, it is often not a great place to store green coffee. Temperature- and humidity-controlled environments are now becoming more prevalent as a means to extend the life of green coffee.
SEE ALSO
Freezing p98
Fresh crop p103
Green p109
India p124
Old Brown Java p163
Resting p189
Peaberry | COFFEE BEAN TYPE
There are many coffee terms and technical definitions that you will see on packaging and websites. It can be overwhelming, and a few key terms often get confused. Peaberry seems to be one of those. You may see a Kenyan coffee that is labelled as a peaberry and you might be forgiven for thinking that this is a variety of coffee. This is not the case, however: all varieties can produce peaberries. The term refers to a natural anomaly that occurs inside the coffee cherry in which only one of the seeds is fertilized and so develops alone inside the cherry. Normally, two seeds grow next to each other, creating a flat side on each where they meet – this is what gives coffee beans their familiar shape. Without the second seed to grow against, the peaberry becomes almost spherical. Certain origins (most prominently Kenya and Tanzania) are more likely to sort the peaberries and sell them separately, whereas many others will not, which is why you do not see peaberries from all origins. Peaberries do taste different from the rest of the crop, and the theories as to what causes the difference are as follows: (1) the peaberry gets more of the cherry’s nutrients; (2) the spherical shape and density of the bean means it can roast more evenly; and (3) the fact that the peaberry has to be so carefully sorted means that it is less likely to contain defects.
SEE ALSO
Defects p67
Kenya p135
Peru | ORIGIN
Peru is a large producer of coffee. The cup profile tends to be round and smooth, with lower acidity and a more nutty, chocolaty quality. The organic certification is very prevalent in Peru, as is the Fair trade certification, though neither really leads to higher cup quality and many of the certified-organic coffees are still sold extremely cheaply. It is not common to see Peruvian coffees stocked and presented by speciality roasters but, as with many producing countries, increasing numbers of traceable and interesting coffees come from the origin.
SEE ALSO
Fair trade p89
Phosphoric acid | GROWING; TASTING
Coffee contains many flavour attributes and one of the most desirable and sought-after elements of a good cup is acidity. Acidity in coffee is not always good, however: a vinegary flavour, for example, would be attributed to acetic acid. It is rather the type and structure of acidity that we are after, and it is possible to link these flavour experiences back to specific acids within the bean. The roasting process alters acids in the coffee bean, but we still rely on them being present in the harvested green coffee. Citric acid is made by all coffee plants due to the process of photosynthesis. Phosphoric acid, however, can become part of the coffee only if it is present in the soil the plant grows in. Many East African coffees display phosphoric acidity, which presents itself as a sparkling, slightly fizzy sensation.
SEE ALSO
Acidity p13
Plunger
See “French press”.
Portafilter | ESPRESSO
Also referred to as the “braccio” (the arm), this word simply means “carry [a] filter”. This term, along with the likes of “group head” and “drip tray”, is a description of integral parts of all espresso machine designs regardless of the manufacturer. The portafilter is the handle that holds the basket. Like other parts of the espresso machine, it is relatively common for the portafilter to be customized with all manner of designs and materials. A pro tip is to add small weights or tape to the portafilter to allow multiples to all weigh exactly the same amount. This eliminates the need to constantly tare the scale when using an espresso machine with multiple groups.
SEE ALSO
Basket p23
Espresso p79
Weighing scales p239
Pour-over
See “Full immersion”.
Pressure | ESPRESSO
Espresso is a coffee brewed under pressure, but what exactly is the pressure doing to the coffee and the drink? Brewing espresso under high pressure drives the CO2 out of the coffee, which then becomes the crema on top of the espresso. The pressure allows us to grind finer and increase extraction potential by having enough force to pass the water through the finely ground coffee. Without pressure, the water would just get stuck. It is fascinating to compare the flavours of the same strength beverage at two slightly different pressures, say 7 bar and 9 bar. The exact cause of these differences is hard to figure out as there are so many variables occurring at once. Pressure has an intimate relationship with the grinder, too: grind too fine and the water cannot pass through the puck, no matter the pressure. There might be a sweet spot, but this is one of many unanswered questions in coffee. Other methods like the moka pot and the Aeropress produce pressure but in much smaller and less measurable amounts.
SEE ALSO
Aeropress p13
Crema p63
Espresso p79
Moka pot p149
Producing | GROWING
When it comes to coffee, the world tends to be broken up into consuming and producing countries. Do you grow or do you drink? For the majority of coffee’s trading history, most of the coffee grown has been consumed outside the countries growing it. This is due to its value as an exported good. The irony is that the high-quality coffee is far too valuable to stay, and so the coffee consumed internally is the lower-grade gear. Things are a changing, though: as countries like Brazil and Colombia prosper economically and modernize, their café cultures are expanding and more and more coffee is being consumed within the countries of origin.
SEE ALSO
Brazil p35
Colombia p60
Q
Q Grader | QUALIFICATION
Administered by the Coffee Quality Institute, the Q Grader qualification is the most prestigious in the coffee industry. It consists of an intensive weeklong course and exam that tests the individual’s ability to taste and grade coffee. Twenty-two individual tests must be passed to become a Q Grader. These cover everything from picking out the amount of salt and sugar dissolved in test waters to general knowledge tests and coffee scoring. Qualifications in speciality coffee are becoming more prevalent as the industry grows and matures. The Q Grader qualification has applicability
across all commercial coffee and not just speciality coffee. There is also an R Grader qualification, which focuses on the discipline of grading and understanding the Robusta species and the coffee it produces.
Quaker | DEFECTS
Have you ever spotted a very blond-looking bean among all the brown beans in a hopper or bag of roasted coffee? This is a quaker, and you don’t want it to be there. This is a seed that came from an underripe cherry during harvesting. The wet-process method is able to almost eliminate quakers, as they generally float to the top when submerged in water. The natural processing method makes them harder to spot, and so it is often in coffees processed this way that you spot one. If you see a quaker, snatch it out of your dose or bag and chuck it on the compost heap – and enjoy a tastier cup of coffee.
R
Radiation | ROASTING
When you roast a coffee you are essentially cooking it and, just like heating food, there are various ways in which you can cook a coffee. The two most commonly used methods are convection and conduction: the application of heat either through the use of hot air (convection) or by making a container such as a drum hot (conduction), which then transfers heat to the beans. Different roasting machines can play around with the amount of each cooking force (you could, for example, have a roaster that is more air driven or one that is more drum driven), and the different processes alter the way in which the bean is cooked and how it tastes. The fastest roasters, though, are those that use convection. Less common is the use of radiation, as in the domestic microwave oven. The radiation vibrates the water molecules in the food, which then heat up and cook the food. What is especially interesting here is the potential for more even heating throughout the beans, as the centre gets heated at the same time as the outside. The exact differences in flavour radiation produces are not particularly well documented, but this roasting technology is increasingly being explored and with great results.
Raised beds | PROCESSING
After coffee cherries are picked, the cherry must be removed and the seeds (coffee beans) dried. Coffee must be dried to the point of 12 percent moisture content before export. There is a variety of methods for the removal of the cherry and the drying of the bean, all of which come under the bracket of “processing”. Even though the cherry has spent nine months maturing on the branch of a coffee tree (according to the terroir), this relatively short process has a huge influence on the taste and quality of the coffee. Raised beds can be used to dry the bean with varying amounts of cherry still intact. The main idea behind the beds is to help control the drying process by lifting the coffee from the ground and allowing air to circulate around all the coffee, enabling more even and predictable drying with less problematic fermentation. There is a strong correlation between raised beds and increased cup quality.
SEE ALSO
Species p202
Honey process p118
Natural process p156
Terroir p214
Washed process p235
Rate of rise | ROASTING
This technical industry term refers to the change in temperature of your beans as they get hotter, describing the rate at which the bean is heating up. Coffee expert and author Scott Rao has been influential in coffee brewing and roasting and has popularized the term “rate of rise”. He draws a correlation between a continually decreasing rate of rise and a better roast. This means the bean takes on heat more quickly at the beginning and more slowly as the roast goes on. This requires a fine balance, however; if the heat of the roast begins to reverse and the beans start getting cooler, then we get something called a “baked roast”, which tastes flat and bland.
SEE ALSO
Development p71
Refractometer | TESTING
Refractometers are used in a number of industries and work on the principle of light refraction – it is all in the name. You take a sample of a liquid and the apparatus shoots light through it, measuring how the solids suspended in the liquid push the light around. The concept is then to work back from here and figure out how many solids are in the liquid based on how much the light is refracted. The same apparatus is used in wine and fruit to measure ripeness and figure out sugar concentration, but in coffee it is used to measure the amount of coffee solids that have ended up in the beverage. The results must be considered in context, though they do have the potential to provide insights into the coffee-making process.
SEE ALSO
Brix p38
Extraction p86
Resting | FRESHNESS
The concept of freshness in coffee is easy. When a coffee is harvested, it is at its most fresh. Freshness from roast is at its height when the coffee is pulled out of the roaster’s cooling tray. Freshly ground coffee is coffee that was ground immediately before being brewed. This idea of freshness has become intrinsically linked to ideas of quality. So fresh is best …? Not quite. “Fresh is best” is an easy narrative and one that is broadly true. Coffee harvested eighteen months ago does not score as well as coffee harvested last week. Coffee roasted yesterday tastes better than coffee roasted a year ago, and so on. However, the best results lie somewhere in between, and, for the most part, very fresh coffee is not optimal. Coffees can have a “green” quality just after being harvested; they are often a touch astringent and lack sweetness and structured acidity. Coffee that has just been roasted needs to lose the CO2 and will often “open up” several days after roast. In fact, depending on the coffee and the roasting style, this flavour peak can be much longer after roast, around three to six weeks in some cases. The roaster will be able to advise on when they think their coffee is at its best.
SEE ALSO
Green p109
One-way valve p164
Oxidation p167
Reverse osmosis | FILTRATION
This type of filtration is often a slightly more complex and expensive process than that provided by cartridge filters (ion exchange cartridges). In reverse osmosis, water is forced at high pressure against a membrane and you end up with an almost mineral-less solution on one side and a highly concentrated solution of minerals on the other. Most people use the “empty” side and add a bit of the concentrate back in. In soft water areas it is not unheard of to reverse this so as to increase the mineral content. In very hard water areas reverse osmosis is the only way to push mineral content down, unless you distill your water. Reverse osmosis systems can be quite wasteful, in some cases creating 50 percent waste water, but many systems have greatly improved upon this. From a coffee point of view, the key thing to realize is that, like cartridge-based filtration, the system can only manipulate the water that you started with. Remineralization systems do exist and are increasingly being explored. These will allow more control over actual water composition.
SEE ALSO
Buffer p38
Cartridge filter p48
Water p236
Ripe | HARVESTING
It is widely held that perfectly ripe cherries contain the best coffee. There are, however, times in coffee production when “overripe” cherries will be chosen for the specific flavour profile they can bring. Perhaps the most pertinent question is: exactly what constitutes a ripe coffee cherry? It is most frequently the coffee cherry’s appearance that is used as a guide to ripeness. For most varieties this will be when the coffee is at its most vibrant red before it starts to go purple and brown, which are indicators of overripeness. So while we can all agree that ripe cherries produce the best results in the cup, the exact shade of red can often vary from variety to variety, and nowadays it is more common for farmers to measure the sugar content of the cherry to help discern optimal picking times. Handpicking has its benefits here, but modern technology can also achieve excellent results by sorting the cherries after they have been harvested. In countries like Brazil a big tractor will strip the coffee plants and then all manner of gizmos are used to sort ripe from unripe – such as pressure sorters that measure how hard the cherries are.
SEE ALSO
Brazil p35
Brix p38
Refractometer p189
Robusta
See “Species”.
Roller grinder | GRINDING
The most common way to grind coffee that you will see in shops and homes around the world is burr grinding. However, there are multiple ways to grind coffee. Blade grinders are the least desirable; they hack at the coffee and create a very uneven spread of sizes. Roller grinders are popular with commercial coffee companies. Imagine two rolling pins with spiked surfaces that sit atop one another. The coffee passes between them and gets ground down in the process. Roller grinders can have several series of rollers and are capable of producing very evenly ground coffee as well as grinds that are more spherically shaped.
SEE ALSO
Flat burr p93
Rwanda | ORIGIN
Rwanda is a country that can produce exceptional cup qualities, abundant with flavours of berry fruits and florals, winey acidity, and complexity. Rwanda is a relative newcomer to the speciality scene; the country’s coffee-producing past was largely commercial and limited in scale. Add to this the turmoil of the mid-1990s, meaning that it was not until mid-2000s that the first washing station was built. Since then, Rwanda has become the first and only African country to host a Cup of Excellence and the coffees from this origin have started to get the recognition they deserve.
The Coffee Dictionary Page 9