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The perfect cup of joe might be a matter of taste, but knowing the science behind the coffee-making process could help you elevate your at-home brewing game. Today, barista champion Sam Spillman on the chemical processes behind coffee and her technical approach to the craft.

Have your own approach to coffee chemistry? Tell us at shortwave@npr.org.
This episode was produced by Chloee Weiner, edited by Rebecca Ramirez and fact-checked by Rachel Carlson.

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How To Brew Amazing Coffee With Science : Short Wave

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The perfect cup of joe might be a matter of taste, but knowing the science behind the coffee-making process could help you elevate your at-home brewing game. Today, barista champion Sam Spillman on the chemical processes behind coffee and her technical approach to the craft. Have your own approach to coffee chemistry?

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Human “sniffers” described the flavor as “raspberry notes with a hint of rose water.”

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Coffee with milk may have an anti-inflammatory effect

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Can something as simple as a cup of coffee with milk have an anti-inflammatory effect in humans? Apparently so, according to a new study from the University of Copenhagen. A combination of proteins and antioxidants doubles the anti-inflammatory properties in immune cells. The researchers hope to be…

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The Science of Coffee is a journey into coffee’s hidden microscopic secrets to help you make even better coffee at home. Across six episodes, documentary maker and coffee professional James Harper takes you deep into the world of water for coffee, coffee extraction, plant genetics, espresso technol…

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In which we metaphorically enter the UCLA Language Acquisistion Lab's recording castle, guided by linguistics researcher Dr. Megha Sundara. NPR science correspondent Sydney Lupkin temporarily takes over the host chair to talk to Sundara about all things baby babble. Along the way, we learn why babies babble, how that babbling can change with exposure to new languages - and if there are any lessons for adults. Questions about other ways we develop? Email us at shortwave@npr.org and we might answer it in a future episode!

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Short Wave - How To Brew Amazing Coffee With Science

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The perfect cup of joe might be a matter of taste, but knowing the science behind the coffee-making process could help you elevate your at-home brewing game. Today, barista champion Sam Spillman on the chemical processes behind coffee and her technical approach to the craft. Have your own approach to coffee chemistry?

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Welcome to Chemistry Connections, our names are Samhita and Hana and we are your hosts for episode 17 called the chemistry behind coffee. Today we will be discussing how chemistry affects the production of coffee.

Segment 1: Introduction to Chemistry Behind Coffee

Coffee is indigenous to countries such as Ethiopia, Brazil, India, Vietnam, Mexico, Indonesia, and Sri Lanka. Coffee beans came to be through a story of an Ethiopian goat herder named Kaldi. When the goats he took care of started to wander, Kaldi found them consuming red berries they had found, Kaldi then gave these berries to a local monk to find out what it was. The local monk gave the berries to religious individuals who found themselves with more energy after consuming them. This was then used to keep people from falling asleep during evening prayer and was later found to be coffee beans. Coffee consists of beans originated from Coffea Arabica, which actually makes up 75% of the world's production of coffee. The cultivation and trade of coffee began in the Arabian peninsula and soon started to become popular in the homes of those in the Middle East. From the Middle East, coffee spread to other countries in the 16th century to countries such as Persia, Egypt, Syria and Turkey. Flavored coffee was introduced when regular coffee was introduced in the mid 15th century. Middle Easterners would often blend coffee with different nuts and spices to enhance the flavor. Coffee is harvested in almost every tropical country within 1000 miles of the equator. Out of the 70 species of coffee that exist, only 3 are cultivated, meaning their beans are either raw, roasted, or whole for the making of coffee. During the roasting process of coffee beans, they undergo a chemical reaction introducing about 800 compounds, ⅓ of which make up aromatic compounds.

Segment 2: The Chemistry Behind Chemistry Behind Coffee

As the beans go into the roaster, there is a decrease in temperature with the reaction being endothermic, meaning it is absorbing energy and that energy is used to evaporate water. Le Chatelier's Principle is used to explain how, once a reaction is at equilibrium, it can be stressed by changing variables in which case it is no longer at equilibrium. The reaction will shift to undo the stress placed on the reaction. We can use Le Chatelier's Principle to support that considering there is a decrease in temperature as the beans go into the roaster, the tendency of the reaction will be to go towards the side where there is no heat, which is the product in this case because the reaction is endothermic, meaning the heat is located on the side of the reactants. The result of this is that the reaction will want to increase the temperature because of that disturbance to return the reaction to a state of equilibrium. The bitter taste of coffee is produced during the roasting process. Heat and atoms have the ability to change the flavor of coffee while it is roasting but the biggest player in the staling of coffee is oxygen. When a solution comes in contact with oxygen it changes the molecular structure. Oxygen pulls away electrons from the other molecules. Since there are an uneven number of electrons, the molecules become unstable. They then begin to react with other molecules around them and this is an example of an intermolecular force called covalent bonding. Covalent bonding occurs between polar molecules that share electrons unequally. It is also an example of an intermolecular force, which is a force that holds molecules together and covalent bonding is one of the stronger ones. Coffee goes stale and reduces the aroma or flavor of coffee. This process doesn't have to happen with the air that's being trapped in the coffee machine but it can happen with the water that's added to the ground coffee. Also, Oxidation occurs more at a high temperature. This is relevant when talking about the staling of coffee. The reason behind the staling of coffee has to do with oxidation. Oxidation is the process by which oxygen loses electrons. The oxygen reacts with the hydrogen, so that water is created. The hydrogen ion by itself makes the coffee more acidic. When the water is first being added to ground coffee, the hydrogen reacts with the oxygen, and the pH of the coffee rises, making it less acidic. Many different acids exist in ground coffee, some of which include phosphoric acid, malic acid, and acetic acid. Acids give off their hydrogen ion in a reaction known as a hydrolysis reaction. A lower pH means a higher acidity while a higher pH means a lower acidity. The pH of the original coffee is between 5.0 and 5.4 ( so its acidic) but its acidity can drop to 4.6 if it is kept hot for 2-3 hours, which is also why it's advised to drink coffee fresh.

Segment 3: Personal Connections

My family and I buy different kinds of coffee beans from Starbucks. My sister and I go to Starbucks at least twice a week, so I was interested in why and how different flavors are created with the explanation of chemistry. I found it interesting how different flavors of coffee were invented at the same time as regular coffee. Everytime my sister and I go to stop and shop we buy different flavored syrups and creamers to enhance the taste of our coffee. Knowing little about the coffee world, and being an avid coffee drinker, I wanted to know more about coffee beans and how they were produced to become such a staple in American households. I was surprised to learn that 75% of the world's coffee actually comes from coffee arabia and originated in the Middle East. Along with this, it was a topic both Samhita and I were passionate about so we would both be interested in learning more about coffee, its background, and its chemical aspects. This topic is important to us because it's something that most people consume many times every day. It's important that people know what they are consuming. Chemistry is all about explaining how the world around us works and learning about the chemistry of coffee is one way to bring together the chemistry we have learned this year and apply it to our everyday lives.

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.
https://cen.acs.org/articles/85/i38/Tweaking-Coffees-Flavor-Chemistry.html https://www.reagent.co.uk/the-chemistry-of-coffee/ https://www.zmescience.com/science/domestic-science/science-scientists-public-30012015/ https://handground.com/grind/the-chemistry-of-grinding-coffee-beans#:~:text=The%20Maillard%20Reaction%20is%20responsible,that%20give%20coffee%20its%20brightness. http://www.madehow.com/Volume-3/Flavored-Coffee-Bean.html https://www.intechopen.com/books/coffee-production-and-research/a-detail-chemistry-of-coffee-and-its-analysis https://www.coffeechemistry.com/chemical-changes-during-roasting
Music Credits

Warm Nights by @LakeyInspired

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Chemistry Connections - Chemistry of Coffee

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Chemistry Connections Episode #17 Welcome to Chemistry Connections, our names are Samhita and Hana and we are your hosts for episode 17 called the chemistry behind coffee. Today we will be discussing how chemistry affects the production of coffee.

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Enter for a chance to win any merch item of your choice, including the new shirt -> patreon.com/chemforyourlife Or buy the new shirt right now!-> chemforyourlife.com/store -------------------------- Bonus Episode: Question and Response 46 In this month's bonus episode, Melissa and Jam respond to comments and questions about rubber, cold brew coffee, crystals, greenhouse gases, and more. Thanks to our monthly supporters * Suzanne Phillips * Venus Rebholz * Lyn Stubblefield * Jacob Taber * Brian Kimball * shadow * Emerson Woodhall * Nichole Criss * Kristina Gotfredsen * Timothy Parker * Steven Boyles * Chris Skupien * Chelsea B * Bri McAllister * Avishai Barnoy * Hunter Reardon ★ Support this podcast on Patreon ★ Check out our website at chemforyourlife.com Watch our episodes on YouTube Find us on Instagram, Twitter, and Facebook @ChemForYourLife. Want to start your own podcast? Use Transistor and you'll have the best podcast platform available. We use it and we are totally in love with it.

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Chemistry For Your Life - How is brewing coffee chemistry?

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Enter for a chance to win any merch item of your choice, including the new shirt -> patreon.com/chemforyourlife Or buy the new shirt right now!-> chemforyourlife.com/store -------------------------- #123 The long overdue cracking open of the door into the chemistry of coffee! First, the chemistry of what happens when you brew coffee.

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The World Atlas of Coffee: From beans to brewing - coffees explored, explained and enjoyed

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Amazon.com: The World Atlas of Coffee: From beans to brewing - coffees explored, explained and enjoyed eBook : Hoffmann, James: Kindle Store

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The Science of Caffeine: The World's Most Popular Drug

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Everything you've ever wanted to know about coffee | Chandler Graf | TEDxACU

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How to Make Coffee: The Science Behind the Bean

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How to Make Coffee: The Science Behind the Bean [Kingston, Lani] on Amazon.com. *FREE* shipping on qualifying offers. How to Make Coffee: The Science Behind the Bean

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Coffee Flavor Chemistry [Flament, Ivon] on Amazon.com. *FREE* shipping on qualifying offers. Coffee Flavor Chemistry

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Espresso Coffee: The Science of Quality [Illy, Andrea, Viani, Rinantonio] on Amazon.com. *FREE* shipping on qualifying offers. Espresso Coffee: The Science of Quality

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The term 'coffee' comprises not only the consumable beverage obtained by extracting roasted coffee with hot water, but also a whole range of intermediate products starting from the freshly harvested coffee cherries. Green coffee beans are, however, the main item of international trade (believed s...

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Coffee - Production and Research presents a diversity of important issues related to coffee, with an emphasis on the science of coffee growing. Coffee is one of the highest value commodities traded worldwide. Cultivated and consumed widely, it generates progress for both the economy and society. Divided into six sections, this book examines two coffee species of commercial importance, Coffea arabica L. and Coffea canephora Pierre ex. A. Froehner. Chapters cover such topics as biotechnology, growing, harvesting, post-harvest handling, quality, chemistry, commercialization, and byproducts of coffee.

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Coffee - Production and Research presents a diversity of important issues related to coffee, with an emphasis on the science of coffee growing. Coffee is one of the highest value commodities traded worldwide. Cultivated and consumed widely, it generates progress for both the economy and society.

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There's a lot going on in your cup of coffee. All those complex and varied taste sensations, the aroma, the 'mouthfeel' or texture of the brew-they all contribute to your overall experience of consuming the drink. And those elements are each the result of some interesting underlying chemistry.

From the farm to your cup, there are many processes that affect the chemical composition, flavour and sensory experience of the beverage you finally get to sip. Generally, the fruit from farmed Coffea plants, called coffee cherries, are harvested, then the outer layer of the cherry is removed in a fermentation process or by drying, revealing the seed or the 'green bean'. The next step, roasting the beans, is also an important process for a number of chemical reactions such as the Maillard reaction (really a series of reactions) and caramelisation, further changing the chemical structure and flavour profile of the beans. As soon as the roasted beans are ground ready for serving, the inside is exposed to air and even more chemical reactions take place.

The entire coffee-making process contributes to the chemical composition and the flavour complexity of the final product, starting with the coffee plant itself and even the soil it's grown in. Image adapted from: Rodrigo Flores via Unsplash; CC0

Every brew you or your barista concocts will have a different chemical composition and provide a slightly varied sensory experience. Let's take a look at some of the key constituents that affect the taste and flavour of coffee.

Alkaloids (caffeine and trigonelline)

Caffeine, an alkaloid, may well be the reason you like to drink coffee. Alkaloids have a stimulating effect on the central nervous system, increasing alertness, and are extractable in water. They have a bitter flavour in their original form.

Caffeine contributes to the strength, body and bitterness which are characteristic of coffee. This may be why the flavour isn't quite the same in decaf coffee. Depending on the species and variety, caffeine makes up 0.6 to 4 per cent of the bean. Roasting does not reduce the amount of caffeine.

Trigonelline is an alkaloid found in coffee beans at slightly lower concentrations than caffeine. It starts to decompose at 160°C so in the roasting process (which is hotter-up to 200°C), more than half the trigonelline is lost, in the process producing aromatic compounds that create sweet, caramel and earthy aromas.

The roasting process is integral for changing the coffee bean chemical structure and creating important flavours and aromas. Image adapted from: Juan Pablo Arenas via Pexels; CC0

Volatile compounds

Volatile compounds are organic compounds that evaporate at room temperature. These are responsible for much of coffee's aroma and generally come about from reactions during the roasting process, but storage may impact them too. They may be grouped by their odour, such as earthy odorants, fruity odorants or spicy odorants.

Chemists are continuing to isolate which volatile compounds create certain attributes of coffee. For example, furan compounds are usually responsible for a sweet, malty aroma and pyrazine compounds contribute nutty, earthy, roasty, green aromas. Investigating all these compounds is a work in progress, as there are more than 1000 volatile compounds found in a typical cup of coffee. They are volatile by name and nature-they tend to fly away before there is time to measure them!

Acids

Green beans have a high level of acidity compared to roasted beans. Acids in coffee include citric, malic, chlorogenic and quinic acids, among others-all of which have a tart flavour and tend to balance the sweetness and bitterness of coffee. The products of broken-down acids are often involved in the Maillard reaction and produce a wide range of compounds including the very bitter-tasting and brown-coloured melanoidins. Thus, the darker the roast, generally, the more bitter the bean will be.

The crema floats on the top of an espresso due to the high content of lipids. Image adapted from: Burst via Pexels; CC0

Lipids (coffee oil)

Most of a green coffee bean is made up of lipids, or coffee oil. During roasting, the lipids move from inside the bean to the surface. Once extracted into the coffee brew, they provide the crema-that creamy, flavourful part floating on the top of an espresso. The oils carry volatile compounds and fat-soluble vitamins. They contribute to the mouthfeel and texture of a brew.

Knowing the chemical intricacies of coffee helps the industry to manipulate parts of the process to obtain a certain taste, aroma or mouthfeel. It is also useful for identifying potential health impacts and effects of coffee. The growers, harvesters, transporters, processors, roasters, baristas and many other people in between have a hand (whether deliberate or not) in influencing how the chemistry will change the end product. No wonder coffee has a lot of character-so much has gone into each cup.

This article was written by Olivia Congdon, Communications Officer, Australian Academy of Science, and has been reviewed by the following expert: Professor Kate Jolliffe FAA Professor of Chemistry, University of Sydney

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A Detail Chemistry of Coffee and Its Analysis

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This review article highlights the detailed chemistry of coffee including its components; chemical constituents like carbohydrates, proteins, lipids, and caffeine; aromatic principles; oil and waxes; and minerals and acids. The high extent of caffeine can be found in the coffee plants; hence, in the second part of the study, various analytical methods are designed for the proper identification, separation, optimization, purification, and determination of caffeine present in coffee, tea, and marketed coffee. These analytical methods are appropriated for the separation and quantification of caffeine. The various analytical methods include spectroscopy methods like UV, IR, and NMR spectroscopy; chromatographic methods like paper, TLC, column, HPLC, and gas chromatography; and hyphenated techniques like LC–MS, GC–MS, and GC–MS/MS. This article compares and contrasts the amount of caffeine by various analytical methods.

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Necessary Equipment

Cupping Glasses Cupping vessels shall be of tempered glass or ceramic material. They shall be between 7 and 9 fluid ounces (207 ml to 266 ml), with a top diameter of between 3 and 3.5 inches (76 - 89 mm). All cups used shall be of identical volume, dimensions and material of manufacture, and have lids.

Sample Preparation

Roasting

The sample should be roasted within 24 hours of cupping and allowed to rest for at least 8 hours.

The roast level for cupping shall be measured between 30 minutes and 4 hours after roasting using coffee ground to the SCA Standard Grind for Cupping and be measured on coffee at room temperature. The coffee shall meet the following measurements with a tolerance of ± 1.0 units:

Agtron "Gourmet": 63.0

Agtron "Commercial": 48.0

Colortrack: 62.0

Probat Colorette 3b: 96.0

Javalytics: same as Agtron measurement using either "Gourmet" or "Commercial" scales

Lightells: same as Agtron measurements using "Gourmet" scale

RoastRite: same as Agtron measurements using "Gourmet" scale

The roast should be completed in no less than 8 minutes and no more than 12 minutes. Scorching or tipping should not be apparent.

Sample should be immediately air-cooled (no water quenching).

When they reach room temperature (app. 75º F or 20º C), completed samples should then be stored in airtight containers or non-permeable bags until cupping to minimize exposure to air and prevent contamination.

Samples should be stored in a cool dark place, but not refrigerated or frozen.

Determining Measurements

The optimum ratio is 8.25 grams of coffee per 150 ml of water, as this conforms to the mid-point of the optimum balance recipes for the Golden Cup.

Determine the volume of water in the selected cupping glass and adjust weight of coffee to this ratio within +/- .25 grams.

Cupping Preparation

Sample should be ground immediately prior to cupping, no more than 15 minutes before infusion with water. If this is not possible, samples should be covered and infused not more than 30 minutes after grinding.

Samples should be weighed out as WHOLE BEANS to the predetermined ratio (see above for ratio) for the appropriate cup fluid volume.

Grind particle size should be slightly coarser than typically used for paper filter drip brewing, with 70% to 75% of the particles passing through a U.S. Standard size 20 mesh sieve. At least 5 cups from each sample should be prepared to evaluate sample uniformity.

Each cup of sample should be ground by running a cleansing quantity of the sample through the grinder, and then grinding each cup's batch individually into the cupping glasses, ensuring that the whole and consistent quantity of sample gets deposited into each cup. A lid should be placed on each cup immediately after grinding.

Pouring

Water used for cupping should be clean and odor free, but not distilled or softened. Ideal Total Dissolve Solids are 125-175 ppm, but should not be less than 100 ppm or more than 250 ppm.

The water should be freshly drawn and brought to approximately 200º F (93ºC) at the time it is poured onto the ground coffee. Temperature needs to be adjusted to elevation

The hot water should be poured directly onto the measured grounds to the rim of the cup, making sure to wet all of the grounds. The grounds to steep undisturbed for a period of 3-5 minutes before evaluation.

Sample Evaluation

Sensory testing is done for three reasons:

To determine the actual sensory differences between samples

To describe the flavor of samples

To determine preference of products

No one test can effectively address all of these, but they have common aspects. It is important for the evaluator to know the purpose of the test and how results will be used. The purpose of this cupping protocol is the determination of the cupper's perception of quality. The quality of specific flavor attributes is analyzed, and then drawing on the cupper's previous experience, samples are rated on a numeric scale. The scores between samples can then be compared. Coffees that receive higher scores should be noticeably better than coffees that receive lower scores.

The Cupping Form provides a means of recording important flavor attributes for coffee: Fragrance/Aroma, Flavor, Aftertaste, Acidity, Body, Balance, Uniformity, Clean Cup, Sweetness, Defects, and Overall. The specific flavor attributes are positive scores of quality reflecting a judgment rating by the cupper; Defects are negative scores denoting unpleasant flavor sensations; the Overall score is based on the flavor experience of the individual cupper as a personal appraisal. These are rated on a 16-point scale representing levels of quality in quarter point increments between numeric values from 6 to 9. These levels are:
Quality Scale
Theoretically, the above scale ranges from a minimum value of 0 to a maximum value of 10 points. The lower end of the scale is below specialty grade.

Evaluation Procedure Samples should first be visually inspected for roast color. This is marked on the sheet and may be used as a reference during the rating of specific flavor attributes. The sequence of rating each attribute is based on the flavor perception changes caused by decreasing temperature of the coffee as it cools:

Step #1 - Fragrance/Aroma

Within 15 minutes after samples have been ground, the dry fragrance of the samples should be evaluated by lifting the lid and sniffing the dry grounds.

After infusing with water, the crust is left unbroken for at least 3 minutes but not more than 5 minutes. Breaking of the crust is done by stirring 3 times, then allowing the foam to run down the back of the spoon while gently sniffing. The Fragrance/Aroma score is then marked on the basis of dry and wet evaluation.

Step #2 - Flavor, Aftertaste, Acidity, Body, and Balance

When the sample has cooled to 160º F (71º C), in about 8-10 minutes from infusion, evaluation of the liquor should begin. The liquor is aspirated into the mouth in such a way as to cover as much area as possible, especially the tongue and upper palate.Because the retro nasal vapors are at their maximum intensity at these elevated temperatures, Flavor and Aftertaste are rated at this point.

As the coffee continues to cool (160º F - 140º F), the Acidity, Body and Balance are rated next. Balance is the cupper's assessment of how well the Flavor, Aftertaste, Acidity, and Body fit together in a synergistic combination.

As the coffee continues to cool (160º F - 140º F), the Acidity, Body and Balance are rated next. Balance is the cupper's assessment of how well the Flavor, Aftertaste, Acidity, and Body fit together in a synergistic combination.

Step #3 - Sweetness, Uniformity, and Cleanliness

As the brew approaches room temperature (below 100º F) Sweetness, Uniformity, and Clean Cup are evaluated. For these attributes, the cupper makes a judgment on each individual cup, awarding 2 points per cup per attribute (10 points maximum score).

Evaluation of the liquor should cease when the sample reaches 70º F (21º C) and the Overall score is determined by the cupper and given to the sample as "Cupper's Points" based on ALL of the combined attributes.

Step #4 - Scoring
After evaluating the samples, all the scores are added as describe in the "Scoring" section below and the Final Score is written in the upper right hand box.

Individual Component Scores

The attribute score is recorded in the appropriate box on the cupping form. On some of the positive attributes, there are two tick-mark scales.

The vertical (up and down) scales are used to rank the intensity of the listed sensory component and are marked for the evaluator's record.

The horizontal (left to right) scales are used to rate the panelist's perception of relative quality of the particular component based upon their perception of the sample and experiential understanding of quality.

Each of these attributes is described more fully as follows:

Fragrance/Aroma | The aromatic aspects include Fragrance (defined as the smell of the ground coffee when still dry) and Aroma (the smell of the coffee when infused with hot water). One can evaluate this at three distinct steps in the cupping process: (1) sniffing the grounds placed into the cup before pouring water onto the coffee; (2) sniffing the aromas released while breaking the crust; and (3) sniffing the aromas released as the coffee steeps. Specific aromas can be noted under "qualities" and the intensity of the dry, break, and wet aroma aspects noted on the 5-point vertical scales. The score finally given should reflect the preference of all three aspects of a sample's Fragrance/Aroma.

Flavor | Flavor represents the coffee's principal character, the "mid-range" notes, in between the first impressions given by the coffee's first aroma and acidity to its final aftertaste. It is a combined impression of all the gustatory (taste bud) sensations and retro-nasal aromas that go from the mouth to nose. The score given for Flavor should account for the intensity, quality and complexity of its combined taste and aroma, experienced when the coffee is slurped into the mouth vigorously so as to involve the entire palate in the evaluation.

Aftertaste | Aftertaste is defined as the length of positive flavor (taste and aroma) qualities emanating from the back of the palate and remaining after the coffee is expectorated or swallowed. If the aftertaste were short or unpleasant, a lower score would be given.

Acidity | Acidity is often described as "brightness" when favorable or "sour" when unfavorable. At its best, acidity contributes to a coffee's liveliness, sweetness, and fresh- fruit character and is almost immediately experienced and evaluated when the coffee is first slurped into the mouth. Acidity that is overly intense or dominating may be unpleasant, however, and excessive acidity may not be appropriate to the flavor profile of the sample. The final score marked on the horizontal tick-mark scale should reflect the panelist's perceived quality for the Acidity relative to the expected flavor profile based on origin characteristics and/or other factors (degree of roast, intended use, etc.). Coffees expected to be high in Acidity, such as a Kenya coffee, or coffees expected to be low in Acidity, such as a Sumatra coffee, can receive equally high preference scores although their intensity rankings will be quite different.

Body | The quality of Body is based upon the tactile feeling of the liquid in the mouth, especially as perceived between the tongue and roof of the mouth. Most samples with heavy Body may also receive a high score in terms of quality due to the presence of brew colloids and sucrose. Some samples with lighter Body may also have a pleasant feeling in the mouth, however. Coffees expected to be high in Body, such as a Sumatra coffee, or coffees expected to be low in Body, such as a Mexican coffee, can receive equally high preference scores although their intensity rankings will be quite different.

Balance | How all the various aspects of Flavor, Aftertaste, Acidity and Body of the sample work together and complement or contrast to each other is Balance. If the sample is lacking in certain aroma or taste attributes or if some attributes are overpowering, the Balance score would be reduced.

Sweetness | Sweetness refers to a pleasing fullness of flavor as well as any obvious sweetness and its perception is the result of the presence of certain carbohydrates. The opposite of sweetness in this context is sour, astringency or "green" flavors. This quality may not be directly perceived as in sucrose-laden products such as soft drinks, but will affect other flavor attributes. 2 points are awarded for each cup displaying this attribute for a maximum score of 10 points.

Clean Cup | Clean Cup refers to a lack of interfering negative impressions from first ingestion to final aftertaste, a "transparency" of cup. In evaluating this attribute, notice the total flavor experience from the time of the initial ingestion to final swallowing or expectoration. Any non-coffee like tastes or aromas will disqualify an individual cup. 2 points are awarded for each cup displaying the attribute of Clean Cup.

Uniformity | Uniformity refers to consistency of flavor of the different cups of the sample tasted. If the cups taste different, the rating of this aspect would not be as high. 2 points are awarded for each cup displaying this attribute, with a maximum of 10 points if all 5 cups are the same.

Overall | The "overall" scoring aspect is meant to reflect the holistically integrated rating of the sample as perceived by the individual panelist. A sample with many highly pleasant aspects, but not quite "measuring up" would receive a lower rating. A coffee that met expectations as to its character and reflected particular origin flavor qualities would receive a high score. An exemplary example of preferred characteristics not fully reflected in the individual score of the individual attributes might receive an even higher score. This is the step where the panelists make their personal appraisal.

Defects | Defects are negative or poor flavors that detract from the quality of the coffee. These are classified in 2 ways. A taint is an off-flavor that is noticeable, but not overwhelming, usually found in the aromatic aspects. A "taint" is given a "2" in intensity. A fault is an off-flavor, usually found in the taste aspects, that is either overwhelming or renders the sample unpalatable and is given an intensity rating of "4". The defect must first be classified (as a taint or a fault), then described ("sour," "rubbery," "ferment," "phenolic" for example) and the description written down. The number of cups in which the defect was found is then noted, and the intensity of the defect is recorded as either a 2 or 4. The defect score is multiplied and subtracted from the total score according to directions on the cupping form.

Final Scoring

The Final Score is calculated by first summing the individual scores given for each of the primary attributes in the box marked "Total Score." Defects are then subtracted from the "Total Score" to arrive at a "Final Score." The following Scoring Key has proven to be a meaningful way to describe the range of coffee quality for the Final Score.
Total Score Quality Classification

90-100 - Outstanding - Specialty

85-99.99 - Excellent - Specialty

80-84.99 - Very Good - Specialty

< 80.0 - Below Specialty Quality - Not Specialty

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Protocols & Best Practices - Specialty Coffee Association

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Cupping Glasses Cupping vessels shall be of tempered glass or ceramic material. They shall be between 7 and 9 fluid ounces (207 ml to 266 ml), with a top diameter of between 3 and 3.5 inches (76 - 89 mm). All cups used shall be of identical volume, dimensions and material of manufacture, and have lids.

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We believe that coffee is more than just a drink: It's a culture, an economy, an art, a science - and a passion. Whether you're new to the brew or an espresso expert, whether you prefer it with or without caffeine, there's always more to learn about America's favorite beverage.

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Coffee is more than just a drink: It's a culture, an economy, an art, a science - and a passion. Whether you're new to the brew or an espresso expert, there's always more to learn about this beloved beverage.

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We're honored to of had some of our research on cold brew chemistry published in this month's issue of Roast Magazine.

The research which was independently conducted by our coffee scientist, Joseph Rivera, utilized high performance liquid chromatography (HPLC) to analyze differences between hot vs cold brewed coffee. Check out the article, it will sure surprise you.

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Explore the chemistry of coffee with our Coffee Science Certificate (CSC) program! We are the leaders in technical training, consulting and testing/analysis. Sign up for our newsletter.

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Have you ever wondered what makes up everything in the world around you? Or what exactly is the difference between solids, liquids, and gases? Have you wanted to know what causes two substances to react or change? Available only in paperback or ebook, Chemistry: Investigate the Matter that Makes Up…

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2003, Carbohydrate Polymers

Polysaccharides were sequentially extracted from green and roasted Coffea arabica beans with water (90 °C), EDTA, 0.05, 1, and 4 M NaOH and characterized chemically. Additionally, the beans were subjected to a single extraction with water at 170 °C. Green arabica coffee beans contained large proportions of 1→4-linked mannans, of which on average 1 in every 23 mannopyranose residues was branched with single unit galactose side-chains at O-6. A part of these galactomannans could be extracted relatively easy with water and EDTA. These galactomannans were found to have a relatively high degree of branching (gal:man∼1:8) and a relatively low molecular weight in comparison to the remaining galactomannans (gal:man∼1:15-24). Additionally, 1→3-linked galactans, heavily branched at O-6 with side-chains containing arabinose and galactose residues, were present in the green coffee beans, as well as smaller amounts of pectins, cellulose, and xyloglucans.

Roasting resulted in a loss of 8% of the dry weight. This could be partly explained by the relatively high percentage of sugars which was lost during the roasting process, most probably as a result of conversion into, e.g. Maillard and pyrolysis products. After roasting the extractability of polysaccharides was increased significantly. A decrease in the degree of branching as well as a decrease in molecular weight of arabinogalactans, galactomannans, and xyloglucans was observed after roasting.

2000, Journal of Biotechnology

Different mannanase preparations obtained from the filamentous fungus Sclerotium rolfsii were used for the hydrolysis of coffee mannan, thus reducing significantly the viscosity of coffee extracts. Mannan is the main polysaccharide component of these extracts and is responsible for their high viscosity, which negatively affects the technological processing of instant coffee. Coffee mannan was isolated from green defatted Arabica beans by delignification, acid wash and subsequent alkali extraction with a yield of 12.8%. Additionally, coffee extract polysaccharides were separated by alcohol precipitation and were found to form nearly half of the coffee extract dry weight. These isolated mannans as well as the mannan in the coffee extract were efficiently hydrolysed by the S. rolfsii mannanase, which resulted in significant viscosity reductions. Concurrently, the reducing sugar content increased continuously due to the release of various mannooligosaccharides including mannotetraose, mannotriose, and mannobiose. Both a partially purified, immobilised and a soluble, crude mannanase preparation were successfully employed for the degradation of coffee mannan.

View all citing articles on Scopus

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The chemistry of coffee extraction in relation to polysaccharides

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Technically produced extracts from roasted Arabica and Robusta coffees contain, just like the infusions prepared in the home, 20-36% carbohydrates, de...