How Does Processing Affect The Chemical Composition And Flavour Of Coffee? Why do sun-dried beans taste different from washed beans? What makes the sweetness of honey-treated coffee more pronounced? Raw bean processing has a huge impact on the flavour, aroma, and fullness of coffee and is an important differentiator for many people when choosing coffee beans. In this article, we look at the chemical changes that occur during processing and how these changes affect the flavour of the cup. Flavors and aromas of coffee from origin Roasting develops the flavour and aroma of the coffee, and the aroma compounds are created by a number of chemical reactions in the raw coffee bean. The degradation of monosaccharides and polysaccharides during the roasting process results in sweetness and caramelized aromas. Conversely, the degradation of hydroxycinnamic acid (a phenolic compound) produces aromatic notes. The conversion of hydroxy amino acids such as threonine and serine into volatile compounds called pyrazines and pyrroles produces the characteristic flavour of coffee roasting. But what does this have to do with processing? Treatment affects the chemicals that are released from the raw beans when they enter the roaster and, therefore the aroma of the coffee produced by the roast. How does the processing method affect the chemical composition of the coffee? The coffee fruit usually has two seeds, the outer seeds are covered by an endocarp and pectin layer, and the outer layer has a pulp and peel. The flesh of the coffee fruit itself contains a large amount of sugar. There are different traditions and innovations around the world, but coffee is usually treated by sun or water washing. With the sun treatment, the coffee is exposed directly to the sun, skin, and flesh. The honey treatment is somewhere in between, where the flesh and skin are removed before drying, but some pectins are retained for processing. The treatment method affects the flavour and aroma because of the sugar changes in the pulp left on the sun or honey-treated coffee, which significantly changes the chemical composition of the raw beans. These changes are reflected in the final sweetness and fullness of the coffee, so let's take a closer look at what happens. An easy and quick caffeine calculator: https://roastercoffees.com/caffeine-calculator Sprouting When the coffee fruit is harvested at maturity, it means that the seeds inside the fruit are about to start sprouting. Germination activates some polysaccharide enzymes, which means that the natural sugars begin to break down. Researchers have found that the enzyme activity of washed coffee is higher than that of sun-treated coffee. This means that some of the aroma compounds and free sugars formed during the roasting process are broken down during the washing process, making washed coffee more refreshing than sun-tanned coffee. It contains fewer aroma compounds but more acidity. Fermentation Due to the fermentation of the sugars in the pulp, sun-dried coffees are sweeter than washed coffees. Sun-washed coffees undergo fermentation, but because the pulp and pectin have been removed, the enzymes used in sun-washed coffees are much lower. During the fermentation process, microorganisms change the proteins, carbohydrates, and chlorogenic acids. More aromatic compounds are produced in sun-dried coffee. The result is the sweetness in the coffee, and the fruity, floral, and caramel notes that can eventually be found in the coffee. In contrast, washed coffee is cleaner and allows the drinker to recognize the flavour of the particular coffee. The honey process involves removing some of the pulp to allow the pectin around the beans to ferment better, which results in a honey-treated coffee that is more pronounced in sweetness, creaminess, and nuttiness than a sun-dried coffee. Fermentation can have a significant impact on the flavour, aroma, and body of the coffee, but the fermentation process needs to be carefully controlled. Over-fermentation can produce too much acetic acid and phenolic compounds, making the final coffee bitter or acidic. Furthermore, the dense and diverse microorganisms present in coffee can lead to inconsistent and unpredictable fermentation results. Beans that have undergone a longer germination period and a shorter fermentation time may have a poorer flavour profile, as both stages help to enhance the flavour of the coffee. The effect of processing on the roasting technique While we have seen the effects of processing on the chemical composition of raw beans, processing also affects the compounds transformed into aromas when roasted. It is important to understand the effects of processing when roasting. Sun-treated coffee retains more sugars and is more sensitive to heat during the roasting process. Simple sugar molecules degrade quickly during roasting and produce an unpleasant burnt flavour. This means that roasters need to be more careful with the roasting curve, especially at the beginning of the roast. Washed coffee is one of the most common and popular processing methods, giving a clean flavour and allowing the taster to enjoy the flavours of the region and variety more distinctly. But there are also many who prefer the sweetness and fruitiness of the sun and honey process. You now have a little idea of how the treatment affects the flavour of whatever coffee you choose. 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