Factors That Influence Coffee Quality And Flavor

As coffee lovers, we know that there is a really broad range of characteristics that you can find in coffee. From earthy tones to sweet fruit flavours, to floral and tea-like aromatics, but what determines which of these characteristics will be found in your cup?Today we shall highlight ten important factors that determine what you’ll taste in your carefully brewed cup of coffee.


For the best tasting coffee, always buy 100% arabica beans. Arabica beans are usually flavor rich, while robusta beans have more caffeine and less flavor and are cheaper to produce. The exception to this rule is that some very good espresso coffees will have small amounts of the highest quality robusta beans on the market.


Coffee demands the perfect balance of sunlight, rain and temperature to produce the highest-quality beans. The climate of a region controls the length of the growing season and whether cherries ripen at optimal times. Even small variations in temperature and rainfall can make a big difference in the quality of the harvest. Soil provides many of the minerals and nutrients that the coffee plant absorbs, and these in turn affect flavor, body and acidity. Cooler temperatures allow cherries to ripen more slowly, developing fuller flavor.


Terroir is the influence of where the coffee is grown. We all know that coffees from Kenya generally taste pretty different to coffees from Brazil. We also know that coffees from nearby areas can have similarities. These are the results of the influences of terroir. Of course the specific elements of a terroir that are responsible for the impact on coffee flavour are numerous and complex, but altitude, climate, soil type, soil micro-biome and topography are some of the important factors. Paying attention to where your coffee comes from, and what some of the defining characteristics of that terroir are is helpful if you want to understand your coffee better.


The best coffees come from regions where farmers have implemented farming practices and techniques that coax the best flavors from the bean. Proper fertilization, irrigation, pruning and care encourage the development of high-quality coffee. These practices have a huge impact on the taste of the coffee you drink. Everything from the use of chemicals to planting patterns ultimately affect the nature of the crop. One particularly important practice is picking. Coffee is best when it is picked at optimal ripeness, but since coffee cherries don’t ripen at a uniform rate, for the best results, cherries must be picked by hand, by labourers who are trained to pay attention to the ripeness of the fruit they are harvesting. Once coffee cherries are harvested, they must be processed immediately to avoid mold or rotting.


There are three main ways of processing coffee cherries, and each contributes very different qualities to the finished coffee.

Dry or natural processing: The coffee cherries are spread out to dry on rooftops or platforms in the sun for seven to ten days. During the drying phase, the cherries must be raked and turned regularly to prevent the development of mould, which would contribute “off” flavors. Once the skin and fruit have become brittle, they are removed from the bean, usually by hand. These coffees tend to have fuller body, thicker viscosity and more restrained acidity with an earthy taste. They also exhibit wild, rich fruit flavors that are seldom found in washed coffees.

Washed or wet-processed coffees: This more modern style of processing involves briefly fermenting the coffee cherries and then removing the seeds from the fruit or pulp. This method has an advantage in that with the outer, fruity layer, some of the risk of spoilage is removed. Wet-processed coffees generally have a cleaner profile with brighter acidity and light to medium body.

Pulp natural or semi-washed/honey-prep processingis a hybrid method where the coffee cherries go through the first step of the washing process to remove the outer skin, but are allowed to dry with the fruit pulp clinging to the parchment layer covering the bean instead of immediately undergoing fermentation and washing . Pulp natural coffees tend to taste cleaner than dry-processed coffees but are perceived to have more body and muted acidity than fully washed coffees. They frequently exhibit sweetness, especially honey, brown sugar and caramel flavors, and a level of fruitiness that falls between that of wet- and dry-processed coffees.


Coffee cherries are sorted immediately after harvest to remove unripe and substandard berries. During wet processing, beans that float are removed and discarded, adding a second layer of sorting. Regardless of the processing method used, beans may be sorted again for size, shape and color before milling and packaging. Each sort removes coffee beans that don’t meet particular standards, leaving only the highest-quality beans to make it into your cup.


While green coffee beans don’t stale as quickly as roasted coffee beans, they will lose flavor over time. The way they are stored before, during and after shipping can significantly affect cup quality many importers prefer coffee shipped in alternative containers which protect the beans from moisture, odors and other outside factors that can affect the flavor. Coffee stored in a warehouse for months or, in some cases, a year or more, will not be as flavorful as coffee that is fresh from harvest. With proper packaging, whole bean coffee can be stored up to 4 weeks in valve-seal bags and still be full flavored, though aiming for drinking within 2 weeks is ideal. For freshness it is better to buy vacuum packaged containers with expiration date and valves that allow CO2 to escape while keeping oxygen out of the bag to ensure freshness.


Roasting affects coffee flavor profoundly. Heat causes chemical changes within the coffee bean, caramelizing the sugars and bringing out the flavors of the acids and other elements present. The same coffee will taste completely different at a light roast level than it does at a medium or dark roast level.  After sourcing and selection, the roaster helps to realise the full potential of the coffee by carefully crafting a roast profile that will suit that set of beans. The roaster has to fine tune variables like roast time, charge temperature, rate of rise, drum speed, air flow & cooling speed, while responding to data like temperature logs, first and second crack timing, and most importantly sensory experience.


Single origins are becoming increasingly popular, probably because they allow the drinker to experience the fruits of the coffee farmer’s labour quite literally. Even so blending can be a masterful craft in its own right. In its basic forms, it can ensure a more consistent flavour experience throughout the year as the inputs to that blend change with the season. At its best, a blend can be a unique taste experience, whose flavour is more than just a sum of those of its component parts.


One mistake that new coffee lovers make is assuming that the exact same brewing parameters will bring out the best in every coffee. Your brewing variables need to match the coffee your brewing as well as the brew method. The method may even need to be tweaked to respond to ambient conditions like heat, humidity and altitude. Even in a simple manual brew method, changes in brewing variables can be the difference between a decent and a delicious cup. Some important variables are:

Grind size and uniformity

The finer a coffee is ground, the more surface area there is and the larger the grind, the smaller the surface area.  The optimum grind (coarseness) is somewhere between the two extremes. If you get a cup of coffee produced from a quality bean but it is too weak and insipid, the coffee may have been ground too coarsely. If the coffee is unacceptably bitter, perhaps the grind is too fine, with too-high levels of organic acids being extracted.

Water Temperature

Temperature strongly influences solubility and rates of extraction. The solubility of caffeine is moderately affected by temperature and the solubility of the organic acids is strongly affected by temperature.

Extraction Time

The ideal cup of coffee is one that has maximum caffeine and maximum volatile oils while limiting the bitter organic acids, 4 minutes should be just about perfect for the perfect brew. If extraction takes only two minutes you will have a coffee high in caffeine but weak in flavour, aroma and bitterness. If extracted for too long, say to 8 minutes, the coffee will contain high amounts of organic acids, which can make it unacceptably bitter.

Coffee-to-water ratio

This is perhaps the most subjective of all tests. Too little coffee even with all variables optimised the coffee will taste weak. Too much coffee and the resulting brew will be too strong and overpowering. The generally accepted rule of thumb is approximately 10g of coffee to 200ml of hot water. Be sure to use clean, fresh water and equipment free of oil residues from the last brew.