Coffee
THE HISTORY OF COFFEE
Legend has it that coffee was discovered by an Ethiopian goat herder named Kaldi. One day, he noticed his goats skipping around in an unusually spirited manner. He observed that they were also eating the berries of a nearby shrub. Not being one to be left out of all the fun, he decided to try the berries himself. He was energized and pleased with the effects the cherries had on him. He told his friends, and soon word spread throughout the region. The rest is history
1000 A.D.: Arab traders bring coffee back to their homeland and cultivate the plant for the first time on plantations. They also began to boil the beans, creating a drink they call "qahwa" (literally, that which prevents sleep).
1453: Coffee is introduced to Constantinople by Ottoman Turks. The world's first coffee shop, Kiva Han, opened there in 1475. Turkish law makes it legal for a woman to divorce her husband if he failed to provide her with her daily quota of coffee.
1511: Khair Beg, the corrupt governor of Mecca, tried to ban coffee for feat that its influence might foster opposition to his rule. The sultan sent word that coffee is sacred and has the governor executed.
1600: Coffee, introduced to the West by Italian traders, grabbed attention in high places. In Italy, Pope Clement VIII was urged by his advisers to consider that favorite drink of the Ottoman Empire part of the infidel threat. However, he decided to "baptize" it instead, making it an acceptable Christian beverage.
1607: Captain John Smith helped to found the colony of Virginia at Jamestown. It was believed that he introduced coffee to North America.
1645: First coffeehouse was opened in Italy.
1652: First coffeehouse was opened in England. Coffee houses multiplied and became such popular forums for learned and not so learned discussion that they were dubbed "penny universities" (a penny being the price of a cup of coffee).
1668: Coffee replaced beer as New York City's favorite breakfast drink.
1668: Edward Lloyd's coffeehouse opened in England and was frequented by merchants and maritime insurance agents. Eventually it became Lloyd's of London, the best-known insurance company in the world.
1672: First coffeehouse was opened in Paris.
1675: The Turkish Army surrounded Vienna. Franz Georg Kolschitzky, a Viennese who had lived in Turkey, slipped through the enemy lines to lead relief forces to the city. The
fleeing Turks left sacks of "dry black fodder" that Kolschitzky recognized as coffee. He claimed it as his reward and opened central Europe's first coffee house. He also established the habit of refining the brew by filtering out the grounds, sweetening it, and adding a dash of milk.
1690: With a coffee plant smuggled out of the Arab port of Mocha, the Dutch became the first to transport and cultivate coffee commercially, in Ceylon and their East Indian colony - Java, source of the brew's nickname.
1713: The Dutch unwittingly provided Louis XIV of France with a coffee bush whose descendants had produced the entire Western coffee industry when, in 1723, French naval officer Gabriel Mathieu du Clieu steals a seedling and transports it to Martinique. Within 50 years, and official survey records 19 million coffee trees on Martinique. Eventually, 90 percent of the world's coffee had spread from this plant.
1721: First coffee house was opened in Berlin.
1727: The Brazilian coffee industry got its start when Lieutenant colonel Francisco de Melo Palheta was sent by the government to arbitrate a border dispute between the French and the Dutch colonies in Guiana. Not only did he settle the dispute, but also stroke ups a secret liaison with the wife of French Guiana's governor. Although France guarded its New World coffee plantations to prevent cultivation from spreading, the lady said goodbye to Palheta with a bouquet in which she hid cuttings and fertile seeds of coffee.
1732: Johann Sevastian Bach composed his Kaffee-Kantate. Partly an ode to coffee and partly a stab to the movement in Germany to prevent women from drinking coffee (it was thought to make them sterile), the cantata included the aria, "Ah! How sweet coffee taste! Lovelier than a thousand kisses, sweeter far than muscatel wine! I must have my coffee."
1773: The Boston Tea Party made drinking coffee a patriotic duty in America.
1775: Prussia's Frederick the Great tried to block imports of green coffee, as Prussia's wealth was drained. Public outcry changed his mind.
1886: Former wholesale grocer Joel Cheek names his popular coffee blend "Maxwell House," after the hotel in Nashville, TN where it was served.
Early 1900's: In Germany, afternoon coffee became a standard occasion. The derogatory term "KaffeeKlatsch" was coined to describe women's gossip at these affairs. Since broadened to mean relaxed conversation in general.
1900: Hills Bros. began packing roast coffee in vacuum tins, spelling the end of the ubiquitous local roasting shops and coffee mills.
1901: The first soluble "instant" coffee was invented by Japanese- American chemist Satori Kato of Chicago.
1903: German coffee importer Ludwig Roselius turned a batch of ruined coffee beans over to researchers, who perfected the process of removing caffeine from the beans without destroying the flavor. He marketed it under the brand name "Sanka." Sanka was introduced to the United States in 1923.
1906: George Constant Washington, an English chemist living in Guatemala, noticed a powdery condensation forming on the spout of his silver coffee carafe. After experimentation, he created the first mass-produced instant coffee (his brand is called Red E Coffee).
1920: Prohibition had gone into effect in United States. Coffee sales boomed.
1938: Having been asked by Brazil to help find a solution to their coffee surpluses, Nestle Company invented freeze-dried coffee. Nestle developed Nescafe and introduced it in Switzerland.
1940: The US imported 70 percent of the world coffee crop.
1942: During W.W.II, American soldiers were issued instant Maxwell House coffee in their ration kits.Back home, widespread hoarding led to coffee rationing.
1946: In Italy, Achilles Gaggia perfected his espresso machine. Cappuccino was named for the resemblance of its color to the robes of the monks of the Capuchin order.
1969: One week before Woodstock, the Manson Family murdered coffee heiress Abigail Folger as she visited with friend Sharon Tate the home of filmmaker Roman Polanski.
1971: Starbucks opened its first store in Seattle's Pike Place public market, creating frenzy over fresh- roasted whole bean coffee.
HARVESTING COFFEE BEANS
→ First of all, coffee beans are not actually beans, but the seed of a cherry from a coffee tree. These trees grow in subtropical climates from sea level to around 6000 feet.
→ the fruit of the cherry needs to be removed from the seeds.
This is accomplished by either of 3 ways:
✓ Dry Process: Also known as the unwashed or natural process. In this process, the newly harvested coffee cherries are sorted and sun dried.
✓ Semi Dry Process: Also known as the "wet hulled" or "semi- washed" process, this process involves wet grinding in which the skin of the coffee cherries are mechanically removed by a pulping machine. Afterwards, the mucilage may be washed off before the coffee beans are dried. In some cases, the mucilage is not washed off and the coffee beans are allowed to sit for a day before being dried.
✓ Wet Process: Generally, the wet process involves washing the pulp of the coffee cherries to reveal the coffee beans. Wet processing is often used to reduce the acidity in gourmet coffees; this results in a balanced coffee with a vibrant and almost fruity essence
→ These green coffee beans are then sent to be dried.
→ After drying, they are sorted by size and graded (usually by hand). Then they are bagged and sent to the roasters. The beans will remain green until roasted.
→ It is important to note that green coffee will stay fresh for a very long time. When freshness is talked about in coffee, it means from the date that the green beans have been roasted.
TYPES OF COFFEE BEANS
Robusta/Canephora
Robusta coffee is a lower grade of coffee that is typically grown at lower elevations. It has more of an astringent flavor and contains a higher amount of caffeine. The Robusta trees are easier to grow and maintain. They are also more disease resistant and produce a higher yield. This type of coffee is typically used to achieve a lower price.
Arabica
Arabica coffee is the superior grade of coffee that most people refer to as gourmet coffee. They contain about half of the caffeine of robusta and more desirable flavors and aromatic properties. Much of the coffee grown worldwide is of the Arabica species, but only a fraction meets the standard set by the Specialty Coffee Association of America.
Other Varieties of Coffee Excelsa is a breed of coffee that has a high resistance to diseases and dryness that plagued other coffee varieties. It has a high yield, and its aged beans give a coffee with odorous and pleasant taste like langka or jackfruit and are sometimes confused with the baraco coffee. This variety also grows in lower elevations in the Philippines, particularly areas of Cavite, where the locals prefer it as a blender for their robusta and barako varieties.
Liberica/Kapeng Barako
has bigger berries. It is relative from West Africa. Liberian Coffee accounts for around 1% of commercially grown coffee. Taste and appearance of the beans and berries are similar to the more common coffee, although beans are often larger but contain a tough, difficult to shell skin, hindering their commercial uses.
COFFEE ROASTING
Coffee Roasting is the art and science of roasting the green coffees at approximately 400 degrees. Although sounding simple, roasting, and blending are two of the most important aspects of creating a great gourmet coffee. The roasting process caramelizes the sugars and carbohydrates in the beans creating an oil-like substance that gives the coffee its flavor and aroma. The longer the coffee is roasted, the darker and oilier its appearance becomes.
ROASTING EQUIPMENT
The two most common types of coffee roasting equipment are the
The drum machines roast the coffee as it is tumbled in a rotating drum.
The hot air machines, also known as fluid bed roasters, roasts the coffee as it tumbles on a current of hot air.
Both machines keep the coffee moving to maintain a consistent and even roast.
Opposite is a drum type coffee roaster you can buy and use in your own kitchen.
Once the coffee roasting begins, at just 3 minutes, the beans emanate a grassy fragrance. At about 5 minutes, the beans begin to swell and change colors from green to yellow and then gold. It is now that the smell changes to that of toasted wheat. At about 9 minutes, the coffee begins to wrinkle and look ruined.
The First Pop:
Around 10 minutes, gasses build up in the beans causing them to swell to about double their original size and then rupture. This rupture releases the gas and can be heard in the roaster kind of like popcorn. The swelling smoothness out the surface of the bean, and then it begins to even out in color to a very light brown. This is the lightest roast and is referred to as cinnamon roast.
The Second Pop:
After about 11 minutes, the color changes to a darker brown known as a full city. At around 12 minutes the color and aroma of the coffee begin to change very rapidly. Just as in the first pop, the gasses build up and burst creating a second pop.
The Dark Roasts:
At around 15 minutes, the coffee beans now look very dark. A little bit more, and we finally come to the darkest roast, the French roast. It is important to note that drum type
THE ROASTING PROCESS
The First 9 Minutes:
machines and the hot air roasters. this has nothing to do with where the beans come from, just how much the beans are roasted. In Europe, this is sometimes known as the Italian or Espresso roast.
COFFEE BLENDING
Coffee blending is the art and science of blending multiple varieties of coffees together to create a balanced, well- rounded flavor and aroma. An example of the world’s most famous blend is the Arabian Mocha Java.
Arabian Mocha Java – This coffee is a blend of coffees from the countries of Yemen and Indonesia. It is known for its rich, spicy taste with bittersweet chocolate overtones.
Coffee producing countries Coffee is a natural product grown in many countries of the tropical and sub-tropical belt in South and Central America, Africa, and Asia. It is grown at different altitudes in different basic climates and different soils and is looked upon as an n international drink consumed throughout the world. Brazil is the world’s largest grower of coffee, Columbia is second, the Ivory Coast third, and Indonesia fourth.
Top Coffee Producing Countries
Brazil- 2,993,780 tons
Colombia- 560,340 tons
Vietnam- 1, 845,033 tons
Honduras- 400,674 tons
Indonesia- 765,415 tons
India- 334,00 tons
Peru-365,582 tons
Guatemala- 226,700 tons
Ethiopia- 456,000 tons
Uganda- 364,760 tons
THE COFFEE GROWING REGION
LATIN AMERICA
→ Colombia- Balanced & Nutty A smooth coffee with a signature nutty flavor
→ GUATEMALA ANTIGUA- It’s an elegant affair: refined in its acidity, identified by the pedigree of its gentle spice flavors and subtle cocoa-like texture.
→ COASTA RICA BELLA VISTA- medium bodied Arabica cofee with crisp acidity and fruity flavor. This coffee came from a small family farm of Fritz Willig in Tres Rios, Costa Rica. A very refreshing coffee that can also be brewed as "iced". Complimentary Flavors: Strawberry, peach, pineapples.
ASIA PACIFIC
The Asia Pacific coffees region includes the Indonesian archipelago. East Timor, South Asia and Papua New Guinea. This large area spans a wide variety of climates and topographies, and some of the world’s distinctive coffees are found here
SUMATRA
Like the lush Indonesian island of its origin, this spicy coffee stands alone. Full-bodied with a smooth mouthfeel, lingering flavors of dried herbs and fresh earth, and almost no acidity
COMPLEMENTARY FLAVORS AND FOOD:
Cinnamon, oatmeal, maple, butter, toffee, and cheese
KOPI LUWAK
From the island of Indonesia comes the world’s most expensive coffee Kopi Luwak. The coffee cherries pass through the digestive track of a civet, a small arboreal mammal the locals call luwak. The beans are collected from the forest floor, cleaned and roasted
PAPUA NEW GUINEA
Bright acidity with lemon and orange citrus notes, smooth body and a cocoa finish.
AFRICA/ARABIA
Home to some of the world’s most exotic coffee, the Africa/Arabia region produces many coffees that set high standards for quality Kenyan and Tanzanian coffee bring to mind images of wide open skies and African landscapes with jacaranda trees towering over coffee farms
ETHIOPIA
This coffee was produced by approximately 50 small independent farms located in the highlands outside of Harrar City in eastern Ethiopia. Unlike most Harrar coffees, these beans come from a single microregion which produces truly distinct Harrar taste characteristics.
Tasting Notes: Dried, dark berry and rummy spice notes with rich chocolate flavors.
Pairing Flavors: Stone Fruits, Chocolate, Spices
ETHIOPIA SIDAMO
Full-bodied and elegantly complex, every sip of SunDried Ethiopia Sidamo is absolutely sumptuous. Tasting Notes: Complex notes of soft pepper, dried dark cherry and chocolate Pairing Flavors: Chocolate, nuts, fruits
KENYA
Juicy & Complex A mysterious and memorable bean. You can recognize Kenya through its tell- tale citrus flavors – grapefruit most often, but sometimes lemon and sometimes tart orange. There’s a sparkle to this coffee, a bright acidity, that makes it so refreshing to drink. In fact, it's a terrific iced coffee on a hot summer day.
ARABIAN MOCHA SANANI
Lush and spicy like wine, with hints of cocoa and dates. Complex, pungent aroma.
Here are some terms used to describe DESIRABLE flavor qualities:
Bright or dry – highly acidic leaving a dry aftertaste
Caramelly – caramel like or syrup
Chocolatey – aftertaste similar to unsweetened chocolate or vanilla
Earthy – a soil-like quality (sometimes unfavorable)
Fragrant – an aroma ranging from floral to nutty to spicy, etc.
Fruity – having a citrus or berry scent
Mellow – a smooth taste lacking acidity but not flat
Nutty – similar to roasted nuts
Spicy – an exotic aroma of various spices
Sweet – a lack of harshness
Wild – a gamey flavor rarely, but sometimes considered favorable
Winy – aftertaste resembling a mature wine
Here are some terms used to describe UNDESIRABLE flavor qualities:
Bitter – aftertaste perceived on the back of the tongue
Bland – neutral in flavor
Carbony – burnt charcoal flavors
Earthy – a musty, soil-like quality
Flat – lacking aroma, acidity, and aftertaste
Grassy – aroma and taste of grass
Harsh – a caustic, raspy quality
Muddy – thick and flat
Musty – slightly stuffy smell (sometimes desirable in aged coffees)
Rubbery – a smell of burnt rubber
Sour – a tart flavor such as unripe fruit
Turpeny – a flavor resembling turpentine
Watery – a lack of body
Wild – a gamey flavor
DECAFFEINATION PROCESS
→ The direct contact method of decaffeination is a process in which chemicals (other than water) are used-on green coffee beans (milled but not yet roasted) with the goal of dissolving and extracting the caffeine.
SWISS WATER PROCESS
→ Swiss Water Process. The Swiss Water Process (SWP) isa non- solvent method for decaffeinating unroasted coffee beans. It was introduced by Coffex in 1979, and was, at that time, the only commercial decaffeination method that did not use solvents
Elements in Brewing the Perfect Cup of Coffee
Coffee - A few kinds of fresh, whole bean coffee
The grind- Roasted coffee must be ground before it can be used to make the brew. Coffee is ground to different grades of fineness to suit the many different methods of brewing. The most suitable grinds for some common methods of brewing coffee are:
Method and Grinding Grade
→ Cafetiere = Medium
→ Espresso = Very fine/ Fine Sugar
→ Filter/Drip = Fine to medium
Direct Contact Decaffeination Process
→ Jug = Coarse
→ Percolator = Medium/Rock Salt
→ Turkish = Pulverized/Baby Powder
→ Vacuum infusion = Medium fine to fine
BREWING COFFEE
→ Brewing coffee is simply the process of flavoring water with roasted and ground coffee beans.
→ Once the package has been opened and exposed to air, a huge amount of the flavor and aroma will have deteriorated within about 7-10 days
→ Drip brewing is the most common method in the United States. It can produce a satisfying cup if properly brewed.
→ First of all, a given amount of coffee only contains so much of the precious oil that give it the flavour and aroma we love. After all of the oils are extracted, the only things you’re getting from the grounds are bitter tasting elements. This is called over- extraction.
→ Brewing coffee begins with using the correct amount of coffee, starting with 2.5 to 3 tablespoons of medium ground coffee per 8-ounce cup.
→ The goal is to adjust the grind so that the entire brew cycle takes between 4 to 6 minutes. If it’s too fast, the coffee will be under- extracted, making it weak and having the little aroma. If too slow, it will be over-extraced and bitter
The French Press:
→ A French press or coffee press is the preferred way by many to brew a cup of coffee. It is also great when you only need to brew a few cups instead of a whole pot of coffee.
→ The way they work is really simple. Just put the recommended amount of ground coffee in the glass pot. This time though, use a course to very coarse grind (similar to very coarse sand or raw sugar).
→ Then pour in water that is not quite boiling (about 200 degrees) and place the lid with the pushdown filter on top but do not press down. This will hold in the heat.
→ Now let the coffee steep for about 3 to 4 minutes. After the brewing time is complete, slowly press down on the filter rod pushing the grounds to the bottom of the pot. Using a coarse grind makes this easier.
ESPRESSO BREWING PROCESS
The Dose and the Tamp:
→ The dose is the amount of ground coffee deposited into the portafilter. Typically, about 8 grams (approx. 2 tablespoons) is used for a single shot and around
Brewing Methods
Drip Brewing: 16 grams for a double. Most portafilters have a fill line, which indicates the proper amount (after compaction) to use.
→ The compaction of the grounds is known as the tamp. This is accomplished with a round, weighted tool that is flat on the bottom and is also referred to as a tamp. First, run hot water through the portafilter, so the cold metal will not cause the brewing temperature to be lowered.
Extracting the Espresso:
→ The ideal brewing time for a 1 oz single shot of espresso is about 22 seconds from the time the brew button is pressed. If it reaches the 1 oz mark before 19 seconds or after 25 seconds, it’s best to pour the shot out and start over.
→ If a 1.5-ounce shot is desired, I use the same amount (4 tablespoons) as a double shot. Then the extraction time should be about 30 seconds.A double shot should take around 38 to 40 seconds to brew.
The Crema:
→ As the streams of espresso are pouring into the shot glass, observe its appearance.
→ This layer is called crema. Crema is a fine celled foam of oil that has the best taste and aromatic properties of the coffee.
→ The perfect shot of espresso has a layer of crema that is thick, consistent in color and remains intact for at least a couple of minutes before settling.
→ Poor crema production is usually a sign of under-extraction but can also be caused by stale coffee, or a low brewing temperature from not preheating the portafilter.
ESPRESSO BASED COFFEE DRINKS
Here are the most common espresso- based beverages:
Straight Espresso
→ A straight shot of espresso is not as popular in the U.S. as in Europe. In fact, it is Italy’s most commonly consumed coffee drink.
→ Part of the reason is that the American pallet is not as accustomed to the strength of straight espresso. In addition, American roasters frequently over-roast the beans leaving a bitter taste. To make matters worse, many coffee bars have neglected to properly train their baristas (the person who extracts the espresso).
→ Nevertheless, here are the variations of the straight shot and remember, always extract directly into a pre-warmed demitasse (small, 2-3 ounce cup), because the shot will cool extremely fast.
The Straight Shot:
Ristretto – (or short shot) Meaning restricted, this is a shot that is stopped at 3⁄4 of an ounce. This restricted extraction ensures that only the best qualities of the coffee are extracted and not the bitter elements. This is the preferred straight shot in Europe.
The Single – Basically a shot extracted to 1 ounce.
The Lungo - (or long shot) a shot extracted to 1.5 ounces.
The Double – A 2-ounce shot using twice as much coffee in the portafilter.
The Americano: An Americano is a really good way to enjoy a regular strength cup of coffee. Simply extract a shot of espresso and fill the rest of the 6 to 8-ounce cup with hot water. This makes a smooth cup of coffee similar to drip brewed.
The Espresso Macchiato: Macchiato means “marked” in Italian. Therefore, this drink is a shot of espresso marked with a small amount of foamed milk dabbed on top with a spoon and served in a demitasse.
Espresso Con Panna: Con Panna means “with cream,” so basically, this drink is the same as a Macchiato except using a dab of whipped cream instead of foamed milk.
Cappuccino: When prepared properly, a cappuccino is made with velvety, wet foam that mixes with the pour instead of a large bubbled meringue floating on top of the espresso
The Caffe Latte: The latte is the coffee drink preferred by most Americans and is easy to prepare. Start with a single shot of espresso for a 6 to 8-ounce drink. Pour in steamed milk, but hold back the foam with your spoon until about 70% to 75% full. Then top it off with foam. For a larger latte (12 to 16 ounces), use a double shot to maintain the coffee flavor.
Flavored Coffee Drinks: When using flavored syrups, add the syrup directly to the espresso and then stir thoroughly before adding steamed or cold milk. This helps the syrup dissolve and mix thoroughly. Also, any of these drinks can be made cold; just use cold milk (not steamed) and add ice and blend if desired.
The Caffe Mocha: The caffe mocha is a variation of the latte but with chocolate syrup added before adding the steamed milk. After the milk is added, an additional stir may be required. Typically, mochas are topped with whipped cream and sometimes chocolate sprinkles.
Flavored Lattes and Cappuccinos: There are many high-quality flavored syrups on the market that can flavor any kind of coffee drink. Some of the more common flavors are vanilla, hazelnut, Irish crème, caramel, peppermint, and butter rum. Even some fruit flavors do well in coffee. Just add the syrup to the espresso, stir, and add steamed milk and stir once more. If you like, top with whipped cream and/or sprinkles.
Other forms of specialty, or connoisseur, coffees are:
Monk’s coffee: Benedictine
Calypso coffee: Tia-Maria
Russian coffee: Vodka
Highland coffee: Scotch whisky
Jamaican coffee: Rum
Seville coffee: Cointreau
Different establishments may give a different name to a specialty coffee containing the same liqueur or spirit. For example:
Café Royale: Brandy
Caribbean: Rum
Café Parisienne: Brandy
Jamaican: Rum
PROPER STORAGE OF COFFEE
As for tea it must be notes that coffee is an expensive commodity and therefore the utmost care must be taken in its storage. Points to note with regard to storage are as follows:
Well-ventilated storeroom
Air-tight container for ground coffee to ensure that the oils do not evaporate, causing loss of flavor and strength
Away from excess moisture
Must not be stored near any strong smelling food, as coffee will absorb their odors
When making coffee in bulk it should be noted that 283.5 – 340 g (10/12 oz) of ground coffee is sufficient to make 4.5 liters (1 gallon) of black coffee. Assuming that cups with a capacity of 1/3 of a pint, 283.5 – 340 grams (10/12oz) of ground coffee is sufficient to provide 24 cups of black coffee or 48 cups if serving half coffee and half milk. When breakfast cups are used, 16 cups of black coffee or 32 cups of half coffee and half milk are available. Capacity at a dinner where demitasse 1/13 of a liter (1/6 of a pint), are used 48 cups of black coffee or 96 cups of half coffee and half milk will result.
The rules for making coffee are:
Use freshly roasted and ground coffee.
Buy the correct grind for the type of machine you may have in use.
Ensure all your equipment is clean before use.
Use a set measure of coffee to water: 283.5 – 340 grams or 4.5 liters (10/12 or per gallon).
Add boiling water to the coffee and allow infusing. The infusion time must be controlled
according to the type of coffee being used and the method of making.Control temperature.
Strain and serve.
Add milk or cream separately.
The best-serving temperature for coffee is 82oC (180oF), and for milk 68oC (155oF)
WEAK COFFEE
Water has not reached its boiling point.
Insufficient coffee used.
Infusion time is too short.
Stale or cold coffee was used.
Incorrect grind of coffee was used for equipment.
FLAT COFFEE
All points as for weak coffee
Coffee left in urn too long before use, or kept at wrong temperature.
Use of dirty urn or equipment.
Water used was not fresh, or boiled too long.
Coffee was reheated.
BITTER COFFEE
Too much coffee was used
Infusion time was too long.
Coffee not roasted correctly.
Sediment remained in storage or serving compartment.
Infusion was at too high a temperature.
Coffee may have been left in urn too long before use.