Are all green coffees the same? What influences flavor in any given coffee? The factors are myriad and there\u2019s not really one definitive answer that will tell you <\/span>exactly<\/span><\/i> what produced a given flavor in a specific bean or brew.<\/span>\u00a0<\/span><\/p>\n However, there are plenty of known quantities in the world of coffee flavor and aroma we can explore together.<\/span>\u00a0<\/span><\/p>\n Flavor, as we perceive it, is related to three distinct sensory experiences that happen more or less simultaneously. On our tongues, we experience texture and weight, something we often describe as \u201cmouthfeel\u201d or \u201cbody.\u201d Our tastebuds also distinguish between primary flavor characteristics of sweet, salty, sour, bitter, and umami (savory).<\/span>\u00a0<\/span><\/p>\n However, it\u2019s our noses that do the heavy lifting when it comes to much of what we describe as flavor. Taste, as it pertains to specific descriptors like \u201cchocolate,\u201d \u201corange,\u201d or \u201cjasmine\u201d et al., is the result of retro-nasal olfaction. Thus, flavor in coffee can be accurately attributed to aromatic compounds.<\/span>\u00a0<\/span><\/p>\n Numerous <\/span>studies<\/span><\/a> and scientific <\/span>journals<\/span><\/a> and <\/span>publications<\/span><\/a> make mention of the fact that coffee contains over 1,000 flavor compounds (known to science as VOC, or \u201cvolatile organic compounds\u201d), though there are <\/span>some who argue<\/span><\/a> that fewer than 50 may be primarily responsible for distinguishable flavors.<\/span>\u00a0<\/span><\/p>\n These compounds are divided into various groups, like aldehydes, acids, furans, phenols, and pyrazines. There\u2019s a convenient list of many influential aromatic chemicals in a recent (2023) food science journal <\/span>publication<\/span><\/a> in Vietnam, and their flavor affiliations.<\/span>\u00a0<\/span><\/p>\n More than any other factor in coffee\u2019s flavor development, there are three primary sources for differentiated tastes in high quality specialty coffee: post-harvest processing, roasting, and brewing.<\/span>\u00a0<\/span><\/p>\n We\u2019ve rambled and written <\/span>lengthy<\/span><\/a> treatises on the flavor of <\/span>fermentation<\/span><\/a>, the <\/span>continuum of flavor<\/span><\/a>, and I don\u2019t think we need to retread all that territory here.<\/span>\u00a0<\/span><\/p>\n Assuming a coffee is handled with care from the start to finish of its journey from tree to port, then there is no greater impact a producer can impart on a coffee\u2019s flavor than that of post-harvest processing. Washed coffees and naturals, honeys, anaerobics, coferments, and any other treatment from the raw fruit to prepared, dried parchment\/pod each have dramatic consequences on the taste of a coffee resulting from varying degrees of microbial and human intervention.<\/span>\u00a0<\/span><\/p>\n Natural coffees are expected to taste fruity as a baseline flavor; some may range from delicately peachy to bombastically berry-like. Cuppers usually avoid overly nutty and bland naturals on the one hand, and winey, boozy, vinegar-like, or composty natural on the other.\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n Washed coffees represent the majority of specialty coffee produced in the world, and are expected to taste clean, mild, and sweet. A typical generic specialty washed coffee from Central America might be caramelly and nutty, while African washed coffees are frequently thought of as being more citric and floral. Generally, traditional washed coffees may taste fruity but rarely dive deeply into berry-like flavors, tasting closer to stone fruit and citrus types of fruit flavors.<\/span>\u00a0<\/span><\/p>\n Wet hulled coffees usually taste a little earthy and herbal, while anaerobically fermented coffees frequently are associated with slightly boozy, funky flavors and elevated fruit notes.\u00a0<\/span>\u00a0<\/span><\/p>\n Coffee, in most modern service environments, is roasted before brewing. It\u2019s an inherently assumed characteristic of enjoying a cup. While many folks can recognize the difference between light and dark roasts, there is <\/span>plenty of craft to be explored<\/span><\/a> when it comes to the fine nature of flavor manipulation.<\/span>\u00a0<\/span><\/p>\n Roast degree, however, more than any other aspect of the process, remains critical in determining a substantial portion of the flavor profile of any given coffee. Research <\/span>published first<\/span><\/a> in <\/span>Beverages<\/span><\/i> in 2020 and <\/span>rewritten<\/span><\/a> for the audience of <\/span>Roast<\/span><\/i> Magazine later that year found that of the variables use to manipulate time and temperature in roasting, none of them mattered as much in terms of flavor than the final roast color.<\/span>\u00a0<\/span><\/p>\n Light roasts tend to highlight a coffee\u2019s acidity, and can showcase delicate floral and fruit flavors. Medium roasts lean more towards caramelized sweetness and a balance of the characteristics of the bean and the influence of the roasting process. Dark roasts typically offer fuller bodied brews with lower acidity and heightened bitterness, with roasty or smokey flavors dominating the experience.<\/span>\u00a0<\/span><\/p>\n However, beyond final roast degree, more subtle but still important flavors can develop depending on the particular approach a roaster takes (the roast profile). Shorter, hotter roasting styles often favor acidity over body, while slower roasting might showcase smoother body while sacrificing acidity. Roasting equipment, airflow, and <\/span>type of heat<\/span><\/a> transfer (conductive, convective, or radiant) may impact flavor as well.\u00a0<\/span>\u00a0<\/span><\/p>\n Check out our <\/span>Roast Glossary<\/span><\/a> for more information.<\/span>\u00a0<\/span><\/p>\n Finally, the preparation of the actual beverage is critically important to flavor. While the majority of professionally brewed coffee typically falls within a narrow range of parameters, it\u2019s possible to make coffee with a very broad variety of brew specs.<\/span>\u00a0<\/span><\/p>\n The coffee center at UC Davis has done <\/span>extensive<\/span><\/a> research on the topic of extraction science. After reviewing and updating the \u201cbrewing control chart\u201d they identified clusters of consumers who preferred various types of brewed coffee beverages, from the high-acidity fruity coffee lovers, to those preferring simple, sweet coffees, to those that loved bitter, heavily extracted brews, they were able to manipulate a particular coffee and roast simply by altering brew ratio, total dissolved solids, and extraction percentages.<\/span>\u00a0<\/span><\/p>\n If the science of extraction isn\u2019t your strong suit, that\u2019s ok. Simple choices like the type of brewing device (filter drip or pour-over, immersion methods like French Press, or espresso) each impact variables like perceived sweetness, acidity, body, and bitterness. Each have their own \u201cideal\u201d brewing parameters, and you can bet that regardless of the method you choose, you\u2019ll find different flavors depending on how finely you grind, how much water you use compared to coffee, and what type of filtration (if any) is employed.<\/span>\u00a0<\/span><\/p>\n If we were to generalize a couple of basic principles based on different brew types, we might expect a few of the following characteristics. Filtered coffee, especially pour-overs, tends to be clean and emphasize acidity and sweetness over body, easily showcasing fruit and floral notes. Immersion-based brew methods, like a French press, often leave a higher lipid concentration in the resulting brew, leaning more towards full mouthfeel and body, with less nuanced fruit or floral character. Espresso, of course, is highly concentrated by comparison and dialing it is an art and craft unto itself, but it will always be much stronger than filtered drip. And cold brew, particularly the common practice of steeping coarsely ground coffee over a long period of time, emphasizes viscosity and acidity, but can be diluted to drinking strength with the addition of water.<\/span>\u00a0<\/span><\/p>\n Brewing involves a surprising number of variables, and it\u2019s one of the unique things about coffee compared to many other specialty foods and beverages, in that its final preparation is often up to the consumer. Variables like water temperature and mineral content, grind size, water-to-coffee ratio, filter type, and even the number of pulses or use of a bloom during pour-over and drip coffee brewing can substantially impact flavor.\u00a0<\/span>\u00a0<\/span><\/p>\n You can check out our <\/span>brewing glossary<\/span><\/a> and guide to <\/span>understanding extraction<\/span><\/a> elsewhere on our website.<\/span>\u00a0<\/span><\/p>\n If we normalize for variables like processing, roasting, and brewing, then we are left with a wide world of exciting, albeit slightly more subtle flavors, from contributing influences such as origin, cultivar, and personal experience, to name a few.<\/span>\u00a0<\/span><\/p>\n I know, I know, you\u2019re furious with me for relegating this critical, coveted facet of flavor to \u201csecondary\u201d status, but please believe me when I tell you I\u2019ve tasted far too many coffees, gems of the soils in which they grew, influenced, overshadowed, or even spoiled by fermentation, roasting, or brewing techniques or errors. Inescapably, even the most recognizable coffee origins bow to the bombastic impact of the big three.<\/span>\u00a0<\/span><\/p>\n However, with thoughtful custodians of coffee at the reigns, terroir can shine. What impacts the flavor of terroir in coffee? Certainly, countries of origin often are associated with strong flavor affinities. Is that a dash of jasmine-like florals in your cup? Probably Ethiopian in origin. Do you taste grapefruit and tomato? Almost certainly Kenya. Is it reminiscent of a snicker\u2019s bar, all peanuts and caramel and milk chocolate? Wouldn\u2019t be surprised if the origin is Brazil. Are we tasting peat moss and fresh earthiness? Could be Indonesian, maybe from Sumatra.<\/span>\u00a0<\/span><\/p>\n Recently, some solid <\/span>academic research<\/span><\/a> points to a potential contributing factor in each of these cases\u2026 local microbiomes. While local soil and available nutrients, variations in rainfall, and degrees of shade all play pivotal roles on that great stage of terroir, it might be the invisible activity of bacteria and yeasts who command the largest presence in the cup.<\/span>\u00a0<\/span><\/p>\n Certain coffee trees have genetically programmed flavors, some more easily distinguishable than others. There are two main commercial species of coffee trees: arabica (which tends to be milder and sweeter) and robusta (which tends towards bolder and more bitter flavors).\u00a0<\/span>\u00a0<\/span><\/p>\n Within the arabica species, hundreds if not thousands of <\/span>varieties have been cultivated worldwide<\/span><\/a> over the course of coffee\u2019s history. Among the most remarkable in the cup include the Gesha variety, known for its intense floral characteristics. Other similarly floral and unique Ethiopian-landrace descendent trees include Chiroso, Pink Bourbon, Sidra, Java, and Wush Wush.<\/span>\u00a0<\/span><\/p>\n Other cultivars with common flavor associations might include SL28, often regarded as high in citric acidity with mild savory herbal notes, Catimors and Sarchimors, which are typically less fruity and more nutty than their 100% arabica counterparts, and Pacamara, known for its unique savory-onion-like characteristics.<\/span>\u00a0<\/span><\/p>\n On a long enough timeline, <\/span>eventually<\/span><\/a> all coffees will taste the same\u2014stale, flattened, faded, papery, dusty. Time marches on.<\/span>\u00a0<\/span><\/p>\n The quest to preserve freshness (and therefore, its flavor), particularly in the last twenty-or-so years of specialty coffee\u2019s story, has evolved to include a multiprong approach. Recognition of <\/span>seasonality<\/span><\/a> has created more sophisticated annual patterns of trade, and not just the ripeness of a coffee cherry, but its proximity to the peak of harvest season can be correlated with freshness and quality of flavor.<\/span>\u00a0<\/span><\/p>\n Understanding the importance of moisture and water activity in the role of aging has led to better controls at origin and preservative packaging like GrainPro and Ecotact bags to help mitigate the migration of a green coffee\u2019s water content. Storage environments are increasingly subject to climate controls, including in some instances employing a <\/span>deep freeze<\/span><\/a>!<\/span>\u00a0<\/span><\/p>\n None of these strategies will stop the spinning wheel of time, but each in their own way acts as a preservative to help keep coffee as fresh as possible for as long as possible, before the flavors of age creep in.<\/span>\u00a0<\/span><\/p>\n Roasted coffee, too, will stale over time. While freezing is an option we\u2019ve explored, and recommend, many roasters prefer to encourage their customers to use coffee within a few days to weeks of the roast date, and employ various types of coffee <\/span>packaging<\/span><\/a> to help preserve the flavor of freshly roasted beans.<\/span>\u00a0<\/span><\/p>\n (This section contains substantial excerpts from my book <\/span>Green Coffee: A Guide for Roasters & Buyers<\/span><\/i><\/a>, used with permission)<\/span>\u00a0<\/span><\/p>\n The most detrimental cup characteristics are recognizable in the cup, nearly-impossible to roast over, and trainable to taste. These primary sensory defects are ferment, mold, phenol\/rio, and potato, and each are related to green coffee handling. An additional secondary defect, quakers, can be identified after roasting.<\/span>\u00a0<\/span><\/p>\n Ferment<\/span><\/b>\u00a0<\/span><\/p>\n Ferment as a sensory defect is the overly fruity, winey, acetic\/vinegar-like flavor most frequently found in washed coffees which have undergone some degree of \u201cover-fermentation,\u201d where microbial activity extends beyond the fruit pulp and into the green coffee seed. It\u2019s usually restricted to a few beans (sometimes identifiable as stinkers or sours) in the batch (perhaps an unstirred pocket of the fermentation slurry), but it could apply to an entire lot which perhaps was left in the tanks too long.<\/span>\u00a0<\/span><\/p>\n \u201cOverfermented coffee\u201d presents a higher than-usual concentration of ethyl esters, and it has been proposed that the \u201cferment\u201d flavor defect, and what cuppers mean by the term \u201cover-fermentation,\u201d is the result of microbes macerating not just the pulp around the coffee but penetrating to the seed itself. This can also appear visually as brownish sours or stinkers.<\/span>\u00a0<\/span><\/p>\n Mold<\/span><\/b>\u00a0<\/span><\/p>\n Mold\u2019s basic sensory character is roughly equivalent to the smell of a musty basement or the flavor of bread mold. It can occur\u2014perhaps more than most other sensory defects\u2014in degrees which can make detection difficult; I\u2019ve worked with many professional tasters who struggle to identify it in low concentrations. As with other primary defects, it may affect a small number of beans in a batch, or the whole lot, and may have occurred at the wet mill, dry mill or during transit or storage.<\/span>\u00a0<\/span><\/p>\n Not all molds are toxic, but an especially high-profile mycotoxin known as Ochratoxin A (OTA) has been detected in coffee. Generally, lower grade commercials, instants and decafs have been the primary source of this kind of contamination in coffee, though that hasn\u2019t stopped well-known brands from touting their toxin-free alternatives. What they\u2019re selling is, in my researched opinion, more about peace of mind than it is <\/span>about clean product<\/span><\/a>.<\/span>\u00a0<\/span><\/p>\n Phenol \/ Rio<\/span><\/b>\u00a0<\/span><\/p>\n Coffee and most other plants are full of phenols. In coffee, tannins in the fruit and chlorogenic acid in the seed are the primary contributors. Phenolic compounds are rich in antioxidants and generally considered as healthy for human consumption.<\/span>\u00a0<\/span><\/p>\n However, the phenolic sensory defect\u2014identified readily by flavors of iodine, band-aid, or \u201chose water\u201d\u2014seems to be primarily the result of either bacterial infection during growth or drying, and drought-conditions. The International Trade Centre (ITC) identifies Carbolic Acid and Hydroxybenzene as synonyms for the defect.<\/span>How Science Explains Coffee Flavor<\/span>\u00a0<\/span><\/h2>\n
Primary Factors – Processing, Roasting, and Brewing<\/span>\u00a0<\/span><\/h2>\n
Post Harvest Processing<\/span>\u00a0<\/span><\/h3>\n
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<\/p>\nRoasting<\/span>\u00a0<\/span><\/h3>\n
Brewing<\/span>\u00a0<\/span><\/h3>\n
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<\/p>\nSecondary Coffee Flavor Factors<\/span>\u00a0<\/span><\/h2>\n
Terroir \/ Origin<\/span>\u00a0<\/span><\/h3>\n
Tree Type<\/span>\u00a0<\/span><\/h3>\n
Freshness, Staleness, Storage Conditions and the Slow March of Time<\/span>\u00a0<\/span><\/h3>\n
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<\/p>\nSensory Defects and Flaws in Green Coffee<\/span>\u00a0<\/span><\/h3>\n