What is Coffee: Definition and 164 Discussions

Coffee is a brewed drink prepared from roasted coffee beans, the seeds of berries from certain Coffea species. All fruit must be further processed from a raw material—the fruit and seed—into a stable, raw product; un-roasted, green coffee. To process the berries, the seed is separated from the fruit to produce green coffee. Green coffee is then roasted, a process which transforms the raw product (green coffee) into a consumable product (roasted coffee). Roasted coffee is ground into a powder and mixed with water to produce a cup of coffee.
Coffee is darkly colored, bitter, slightly acidic and has a stimulating effect in humans, primarily due to its caffeine content. It is one of the most popular drinks in the world, and can be prepared and presented in a variety of ways (e.g., espresso, French press, caffè latte, or already-brewed canned coffee). It is usually served hot, although chilled or iced coffee is common. Sugar, sugar substitutes, milk or cream are often used to lessen the bitter taste. It may be served with coffee cake or another sweet dessert like doughnuts. A commercial establishment that sells prepared coffee beverages is known as a coffee shop (not to be confused with Dutch coffeeshops selling cannabis).
Clinical research indicates that moderate coffee consumption is benign or mildly beneficial as a stimulant in healthy adults, with continuing research on whether long-term consumption reduces the risk of some diseases, although some of the long-term studies are of questionable credibility.The earliest credible evidence of coffee-drinking as the modern beverage appears in modern-day Yemen in southern Arabia in the middle of the 15th century in Sufi shrines where coffee seeds were first roasted and brewed in a manner similar to how it is now prepared for drinking. The Yemenis procured the coffee beans from the Ethiopian Highlands via coastal Somali intermediaries, and began cultivation. By the 16th century, the drink had reached the rest of the Middle East and North Africa, later spreading to Europe.
The two most commonly grown coffee bean types are C. arabica and C. robusta. Coffee plants are cultivated in over 70 countries, primarily in the equatorial regions of the Americas, Southeast Asia, the Indian subcontinent, and Africa. As of 2018, Brazil was the leading grower of coffee beans, producing 35% of the world total. Coffee is a major export commodity as the leading legal agricultural export for numerous countries. It is one of the most valuable commodities exported by developing countries. Green, unroasted coffee is the most traded agricultural commodity, and the coffee trade is the most traded commodity second only to petroleum. Despite the sales of coffee reaching billions of dollars, those actually producing the beans are disproportionately living in poverty. Critics also point to the coffee industry's negative impact on the environment and the clearing of land for coffee-growing and water use. The environmental costs and wage disparity of farmers is causing the market for fair trade and organic coffee to expand.

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  1. K

    Drinking hot coffee - a custom in Italy

    I stumbled upon an unexpected youtube video featuring a young man and his trip to Italy. In the clip, he daringly decided to add a few ice cubes to his cup of hot coffee he just ordered, only to be abruptly interrupted by the vigilant store owner. We often don't see how odd things are when we...
  2. R

    I Multiverse theory, I dont like it...

    In think the popular science discussion about multiverse theory has problems. For example, they suggest that in another universe, coffe is green. Problem, coffe in our universe is brown for a reason, it reflects brown light. If it would reflect green light, it must contain other chemical...
  3. shivajikobardan

    Unable to operate coffee vending machine :(

    Started a new job, this is the coffee vending machine. When I click on cappucino, only cappucino comes and it's very bitter(no sugar). The sugar is in "milk" part. But I am not sure how to turn both milk and cappucino at the same time. I've been making a fool of myself by taking 3 glasses, 1 for...
  4. S

    Sicilian coffee in the "Inspector Montalbano" TV series

    In the "Inspector Montalbano" TV Series, the characters often drink coffee in small cups and it is poured from a small silver colored container. I've read on the internet that typical Sicilian coffee is expresso. Is the series consistent with that? Do homes in Sicily usually have expresso...
  5. S

    Some coffees clog the coffee filter -- Why or how?

    The summary describes the situation. Most coffee ground beans let the hot water go through the filter paper more or less slowly maybe taking a few minutes to brew a serving of coffee through the coffee filter paper. Some other beans, usually of African origin, take much longer to brew. The...
  6. The Bill

    Why/how does filter paper block/trap coffee oils?

    What mechanism or mechanisms cause filter paper to block coffee oils? As I understand it, these "oils" are mostly cafestol and kahweol, which are both functionalized polycyclic molecules with a molar mass around 315. Cloth filters do not prevent these oils from getting into the brewed coffee...
  7. Parkour

    How do you like your coffee?

    I have never been to a coffee shop before. I usually just buy instant coffee and have it with milk and sugar (occasionally I get one from McDonald's) . I hate black coffee but I read that it tastes bad because I am using instant coffee for it. I don't really know much else about coffee but I...
  8. I

    MHB Expected Value of Cup of Coffee in Flip a Lid Contest

    In its flip a lid contest, a coffee chain offers prizes of 50,000 free coffees, each worth \$1.50; two new TVs, each worth \$1200; a snowmobile worth \$15 000; and sports car worth \$35 000. A total of 1 000 000 promotional coffee cups have been printed for contest. Coffee sells for \$1.50 per...
  9. Zohar

    B Why does coffee in a glass leaves its signatory on the surface?

    Some of us may use coffee coaster for our drinks. I was always wondering about that phenomenon and failed to find something on the net yet.
  10. hugo_faurand

    How to measure a quantity of grains for an instant coffee maker project?

    Hello everyone ! I have to built a coffee machine with a coffee tank (instant coffee) and a sugar tank. I'd like to measure a certain quantity of those grains. First, I wanted to make a physical model to know the debit of the grains. But I noticed that it depends on many things like the...
  11. Hemipatuca

    Appliances DIY Drum Coffee Roaster: Motor Power Help Needed

    Hello, My name is Héctor and I love coffee, I'm working on a diy drum coffee roaster. Drum + load= 50 pounds, rotation needed = 10-60 Rpm, length from 20 to 30 cm. How can I determine the motor power that can turn my drum? Can someone help me please? Thank you in advance
  12. The Physics of coffee cooling

    The Physics of coffee cooling

    The physics of how to cool down your cup of coffee or tea fastest. Sponsored by Brilliant: https://brilliant.org/HiggsinoPhysics Stirring vs blowing vs cooli...
  13. BillTre

    Is the Coffee Crisis Approaching?

    Oh, No! Climate change, habitat destruction and other things seem to be putting the the wild relatives of cultivated coffee strains at risk of extinction. This would be a threat to future breeding programs of the currently used cultivars to to enhance their resistant to diseases, drier...
  14. Greg Bernhardt

    B Why did my coffee foam over when I added milk?

    I've made coffee before hundreds of times but today I was startled when poured in a bit of cold almond milk to my very hot coffee resulting in a violent foaming over the cup. It wasn't like a slop over spill. The coffee was not boiling at that moment, but adding the cold milk seemed to create an...
  15. Richie Smash

    What will the final temperature of the coffee be?

    Homework Statement 150g of milk at 10°C is added to 150g of hot coffee at 80°C. Assume they have the same specific heat capacity. The temperature of the coffee decreases: A: to 35 °C B: to 70°C C: by 70°C D:by 35°C Homework Equations Eh= mass x (c) x ΔT Where (c) is specific heat...
  16. Meeeessttteeehh

    Operating cost for lights and coffee machines

    Had a bit of a hard time with this one. Anyone mind giving it a look over? 1. Homework Statement Find the total cost for a business that operates the following for one year. Assume that the rate is 6.4₵/kWh. · Fifteen 100 W light bulbs for an average of eight hours a day. ·...
  17. Delta2

    Caffeine Isomers and Their Effects on the Nervous System

    I noticed that different brands of espresso coffee have different effect on my nervous system. Some are really good in the sense that they wake me up and make me feel fresh and dynamic, while others do nothing, and others make me really jumpy and nervous and stressed. Why is that? I am not good...
  18. ORF

    Medical Why polyphenols make caffeine (from tea) work slower?

    Hello Why polyphenols make caffeine (from tea) work slower than caffeine from coffee? Thank you for your time. Regards, ORF
  19. C

    Finding the Cost for Operating Coffee Machines

    Homework Statement Find the total cost for a business that operates the following for one year: - Fifteen 100 W light bulbs for an average of eight hours a day - Two 15 Ohm coffee makers connected to a 120 V power supply for two hours a day each The rate is 6.4 ¢/kWh Homework Equations ##...
  20. D

    How much pressure do I need to power a keg full of coffee

    Hey everyone, I came across physicsforum.com while trying to answer a puzzling question I'm facing. I'm building a portable nitro coffee dispenser and need to know how much PSI I need to put in a small nitrogen tank to adequately dispense the beverage. Here's the facts; I have a 64oz keg that...
  21. S

    Understanding Sicilian Coffee: Is it the same as Turkish Coffee?

    As a resident of the USA, my only experience with Sicilian coffee is watching how it is portrayed in the "Detective Montalbano" series. The cups are small, which makes me think that it might be a very strong "turkish coffee" beverage. Is it?
  22. Ravi Singh choudhary

    I In which case coffee will cool faster?

    Just Qualitative Analysis: There are many ways of cooling a coffee cup. But here I want to understand about concept of fins. So I am using a spoon to enhance the heat transfer rate. Put the spoon vertically in the cup. We have two ways to put the spoon, other one is upside down. I am curious to...
  23. Sophia

    Tea, coffee and your favourite cups

    So the autumn equinox and colder weather are here. In this time of year, people feel the need to warm up with hot drinks. What's your favourite one? Are you a tea or a coffee person? Or perhaps you prefer cocoa or hot chocolate? Do you care about the specific brand and preparation method? Have...
  24. phillovix

    I Many Worlds Interpretation and Coffee

    Hey there. Based on the many worlds interpretation, is: Everyone simultaneously having coffee with everyone else? Has everyone already had coffee with everyone else? Are these possibilities occurring 'somewhere' continuously? Do these possibilities only occur one at a time, or does the...
  25. jim mcnamara

    What's the Chemistry Behind Your Cup of Coffee?

    http://www.ift.org/~/media/Knowledge%20Center/Publications/Books/Samples/IFTPressBook_Coffee_PreviewChapter.pdf Is an overview of coffee chemical analysis. I biffed a comment the other day about the caloric value of black coffee. So I did some reading. The article is aimed at at Food...
  26. S

    Coffee + Sugar = Extra Calories?

    I am a big physics enthusiast, and I apply my learning as much as possible. Today, my literature teacher introduced this idea that when coffee and sugar are combined, new calories are born. For instance, coffee (0 kcal) + sugar (100 kcal) = 150 kcal? Unfortunately, I only pursued physics and...
  27. B

    Uniform Circular Motion of coffee cup

    Homework Statement Kim has her coffee cup on her car's dash when she takes a corner with radius 4 m and 20 km/h. What is the minimum coefficient of static friction which would allow the coffee cup to stay there without slipping? Homework Equations Can someone show me the steps in how they...
  28. Y

    What is the coffee ring of toluene and hexane?

    When we drop a coffee droplet and wait for it to evaporate, there is a coffee ring left. Because there is coffee dissolved in the solution, and when water can evaporate into the air, the coffee cannot evaporate and it will stay. Therefore, if we drop one DI water droplet onto the substrate...
  29. M

    What type of power cord can I use to fix a coffee maker?

    Hello everybody, I am trying to replace a power cord from a CBTL coffee machine. The cord, which was accidentally cut, has the following description. svt 300v, 18 awg, 105C. I have tried different shops around LA to find the power cord, but the best I was able to find was svt, 300v, 18awg, 75C...
  30. S

    MHB Coffee Addiction: How Much Is Too Much?

    "I hear you drink a lot of coffee." "Yeah, about ten cups a day." "Golly, don't it keep you awake?" "No, but it helps."
  31. mattyboson12

    Designing Disposable Fold-Flat Coffee Cup w/Integrated Lid

    Hi, I am a 2nd year student studying Mechanical Engineering. As part of our design module we are doing a feasibility analysis into a 'disposable Fold-flat cup with an integrated lid' which is to replace existing coffee cups. I understand their are some patents for similar products which would...
  32. N

    Coffee/caffeine and genius within

    I would like to know how many geniuses didnt drink caffeine in a daily basis if any when they did their major work? Or current geniuses? Ive heard rumours that Tesla didnt drink coffee after realizing it affected his imagination, but I don't know if he continued drinking it later on. I read...
  33. C

    Can I Send Her Notes From Class?

    I asked this girl out for coffee 2 days ago and she said yes. Yesterday she e-mailed me and said that she was sick and couldn't make it to class. I told her I hope she feels better soon. Do I ask her if she wants to go out later this weekend or wait a bit, I want her to know I am interested but...
  34. gauss44

    Coffee cup, bomb calorimeter: Open, closed, or isolated?

    Is a coffee cup usually considered to be a closed system? Why or why not? Does it matter that steam or hot coffee may be evaporating? (I think the steam is usually considered to be an insignificant amount of matter, allowing classification to be a closed system, but am unsure.) Is a bomb...
  35. Dennis Roscoe

    Is the Neutron Intermediary Decay W- Boson Related to Gravitational Effects?

    Hi All, If you are in the Milwaukee area, here is a great way to spend a few hours on a Saturday afternoon. COFFEESHOP ASTROPHYSICS Sat Dec 6 2014 2pm @ 224 W. Bruce St, Milwaukee WI 53204 Welcome to CoffeeShop Astrophysics! These are a series of free informal public lectures aimed at anyone...
  36. R

    Finding the Final Temperature of Hot Coffee in a Cold Cup

    Homework Statement (c11p34) You pour 160.0 g of hot coffee at 75.0 oC into a 230.0- g glass cup at 24.0 oC. If they come to thermal equilibrium quickly, what is the final temperature (in oC, enter deg in asnwer box)? Assume no heat is lost to the surroundings. Homework Equations (I don't even...
  37. Ygggdrasil

    Caffeine & Obesity: Scientists Explore Impact on Brown Fat

    Scientists studying obesity have had great interest in brown fat, adipose tissue that actually helps burn fat (for example, to generate body heat in the cold). Studies suggest that higher levels of brown fat correlate with lowered risks for obesity and diabetes, and scientists are studying...
  38. enorbet

    Odd Thermal Reaction of Coffee Grounds

    Greetings While on an elk hunting trip in the mountains we awoke to roughly 2 feet of snow. Everyone wanted coffee and nobody had brought any conventional coffee tools. A cowboy boiled water in an aluminum pot just dumped coffee grounds in the water. Naturally a lot of those grounds floated...
  39. J

    How does hot water brew coffee?

    I wondering what actually happens when you brew coffee (or tea) with hot water. Every source I can find simply talks about how long you need to brew it to "draw out" the flavor or "release" the caffeine. I'm interested in what's actually physically happening to the coffee grounds that makes it...
  40. lisab

    Coffee in the Navy: A Survival Guide.

    Doc Al's recent thread on the effects of coffee on naps got me to thinking: How do you like your coffee? You can check as many categories as you want!
  41. J

    Caffeine and Adenosine: Exploring the Science Behind Coffee Addiction

    I've been performing a little experiment on my self lately. I would routinely drink 1-2 cups a day, so I decided to give it up to see what would happen. Even after two weeks of letting my body forget about the addiction, I feel much more unmotivated and tired. Then I started thinking about how...
  42. A

    MHB Linear Equations - Cost per Pound of Coffee Beans

    My problem is: A coffee house blended 18 pounds of espresso flavored coffee beans with 17 pounds of vanilla flavored coffee beans. The 35 pound mixture cost \$306.50. A second mixture included 19 pounds of espresso flavored coffee beans and 15 pounds of vanilla flavored coffee beans. The 34...
  43. B

    Interesting phenomena of boiled water and my coffee.

    Hello, whilst making my coffee this morning (more like this afternoon, but hey I'm a student), I noticed something that I thought was cool and I'm interested in hearing what you guys think may be happening and/or what you have to say about my ideas. So, I have these 'coffee filters' that are...
  44. M

    Drag Lab Using Coffee Filters

    Homework Statement We are given 3 coffee filters. Using a stopwatch and a meter stick, make measurements to predict how long it would take for those filters to fall down a stairwell. Come up with an experimental method to predict this time. During the lab, we will be told the number of...
  45. B

    Minimizing melted ice in my home-made iced coffee

    Hello - first post to PF. I was making my iced coffee this morning as usual by pouring hot, freshly brewed coffee atop a large cup of ice. I then began to wonder about the thermodynamics of this situation. Will the dV/dt (V=volume, t=time) affect how quickly the ice melts? As I pour in the...
  46. C

    Does coffee help your scientific learning?

    I haven't been drinking coffee for a couple of years due to avoiding any substance that alters psychology significantly. But now I'd like to accelerate studying for a while. Will coffee help me? And what are the best practices about it?
  47. C

    MHB Cost per Pound of Coffee Beans

    A coffee house blended 12 pounds of espresso flavored coffee beans with 11 pounds of vanilla flavored coffee beans. The 23 pound mixture cost \$166.50. A second mixture included 17 pounds of espresso flavored coffee beans and 18 pounds of vanilla flavored coffee beans. The 35 pound mixture cost...
  48. S

    Comparing Coffee Maker Circuits | Are They the Same?

    Are the two circuits attached the same? "Circuit diagram" is the original schematic file, and "circuit" is the one I tried creating online. Are they the same? I am doubtful of the overlapping of the wires and also the power sources. Thanks so much!
  49. K

    Coffee Filter Lab: Finding n for the Drag Force

    If an object of mass M falls under the influence of gravity and a drag force Fdrag, we may write Newton’s Second Law as Ma = Mg - Fdrag Where a is the acceleration of the object and Mg is the weight of the object. The drag force has the general form: Fdrag = bv^n Where the drag...