At a glance

• Aroma is defined as an odour whilst taste is the sense experienced by the tongue and describes sensations of saltiness, sweetness, sourness or bitterness. Flavour is a combination of both aroma and taste.
• A large number of volatile compounds are associated with flavour in coffee, a smaller proportion of which are responsible for coffee aroma.
• Experts define and describe the aroma and taste of coffee, generating profiles that differ according to type of coffee bean, geographical location, level of roasting and preparation method.
• Drinking coffee provides a multisensory experience influenced not only by the type of coffee, preparation method and any additions, but also by the environment including the drinking vessel.

Aroma, taste and flavour

Aroma, taste and flavour are closely connected concepts, however they have distinct definitions.

Aroma is defined as an odour sensed through the nose, and also through the back of the mouth where the nasal and mouth cavities are interlinked. Taste is the sense experienced by the tongue and describes sensations of saltiness, sweetness, sourness, bitterness or umami. Flavour is defined as a combination of both aroma and taste.

Taste and aroma are closely associated with each other and are both perceived by processes within the limbic brain areas that participate in emotion. Aroma plays a particular role in evoking thoughts and emotions that stem from previous experiences and memories. For example, the soft pecan nut and rose hip notes of our Ethiopian Guji can elicit an awareness of calm.

Sensory experts describe the taste and aroma of coffee in great detail and are able to differentiate between different origins of coffee beans, levels of roast and preparation methods. 

Aroma and flavour: composition of coffee

Aroma is one of the first senses experienced when preparing or consuming a coffee beverage.  However, being largely composed of ‘volatile compounds’ that easily evaporate at room temperature, aroma is also one of the most variable components of the sensory experience.

Approximately 850 volatile compounds (aromas) have been identified that are associated with flavour in coffee.  However, a small proportion of these (approximately 40 volatile compounds) with low odour thresholds and/or high concentrations are known to be the main contributors to coffee aroma.

Coffee aroma arises from different volatile compounds produced during the roasting of coffee.  Coffee oil, which makes up approximately 10% of roast coffee beans, carries the most flavour.

As such, green beans have a limited aroma profile that is often described as providing green or musty notes.  However, green beans contain a large number of precursors including sugars, other carbohydrates and nitrogen compounds, which develop into aromatic compounds during the roasting process.

Roasting triggers a series of chemical processes within the beans causing the development of volatile compounds that contribute to the aroma profile. 

Aroma and flavour descriptors

Coffee provides a complex blend of different flavours, which together produce a range of sensory experiences. The sensory profile of a cup of coffee varies according to a number of factors: the type and blend of coffee beans; geographical source; roasting method; and method of preparation. The variation in these aspects will impact the overall sensory experience obtained from a cup of coffee during both the preparation and consumption of the coffee.

Specific aroma and flavour profiles are described by sensory experts, to differentiate different types of coffees and roasts. Aroma and taste, are the overriding factors determining coffee preference. Coffee aroma descriptors include Flowery, nutty, smoky, herby, while taste descriptors include acidity, bitterness, sweetness, saltiness and sourness (see Coffee Flavour Wheel below).

The level of roasting impacts aroma profiles. Research has suggested that lighter roasts preserve the herb and fruit notes, whilst smoky and burnt aromas are increased, and acidity reduced, in darker roasts.

Our Barista Basics online course goes in to more detail about the process of tasting coffee to analyse the flavours and get the most out of your cup. We also regularly host in house cupping sessions of our new single origins.

In vitro research suggests that the release of saliva can affect the aroma experience, with results differing according to brewing method. In addition, it has been suggested that larger sips of coffee appear to generate a stronger release of aroma.

Multi-sensory interactions

The preparation and consumption of coffee provides a complex multi-sensory experience generated by the combined senses of vision, smell, taste, and touch. The experience is also influenced by temperature and the environment in which it’s consumed.

Reaching all the senses

The full sensory experience spans the period of preparation through to consumption.  It begins with the coffee aroma experienced when opening the container, to the visual cues seen when preparing the coffee, including the colour of the coffee and the presence of crema or coffee foam. Arguably, the sensory experience of enjoying a cup of coffee might even start upon entering a coffee shop or roastery and hearing the sound of a machine as research suggests that sound plays an essential role in customers’ daily interactions with products, often influencing their cognitive processes, emotions, and behaviour.

Finally, both the aroma and taste of coffee contribute to the experience of consumption. The addition of milk or sugar to a cup of coffee, not only alters the flavour profile but may also impact aroma, with research suggesting reduced levels of aroma are experienced when additions to coffee are included. Researchers have also suggested that lower fat, homogenised milks, with correspondingly smaller fat globules, can induce a more intense coffee related taste and aroma when compared to whole milk.

The multisensory experience attained when consuming a cup of coffee spans all the senses to deliver the full coffee experience, and enables one to judge the quality and pleasure of the cup of coffee. Drinking a cup of coffee without one of the sensorial cues (e.g. without sensing the coffee aroma) will reduce the impact of the other senses and the overall experience and pleasure derived from the cup of coffee.

The role of appearance

The visual appearance of coffee and how it is presented can also play an important role in the multi-sensory experience and may even impact the perceived taste of coffee. Research has suggested that the colour of the serving cup can impact the perception of taste of the cup of coffee. For example, a white mug was shown to enhance the rating of intensity of a cup of coffee, and was described as less sweet compared to coffee served in a transparent or a blue mug.

Another study on latte art revealed that an angular shape, relative to a more rounded shape, influenced people’s expectations concerning the likability, bitterness and quality of the drink. Thickening the consistency of coffee has also been associated with a reduction in coffee flavour and aroma.

Physiological effects of aroma

Anecdotal evidence suggests that sensing the aroma of coffee may have an impact on feelings of alertness, although further research is required to confirm this. Research does suggest, however, that aroma can trigger emotions and evoke memories.

Animal research has suggested that the roasted coffee bean aroma may have a stress relaxation effect in animals who were sleep deprived, but this is yet to be confirmed in humans. Further information on the role of coffee on mental performance can be found HERE.

Original Article and Research Sources: Coffee and Health.org