The science behind your Nespresso: crema unveiled
Coffee is more than just a beverage: it is a complex sensory experience, composed of the look, the aroma, the taste, and the lingering after-notes. Creating the perfect coffee experience is a science in itself.
The extraction system at the heart of every Nespresso coffee machine manages every variable to ensure optimal aroma and flavour extraction, including the formation of the crema. The crema is formed naturally upon extraction, resulting from a perfect balance of water pressure, temperature, coffee quality, freshness and coffee grinding. The dense, hazelnut-coloured foam layer that forms on top of an espresso coffee is immediately eye-catching prior to consumption, while its smooth, creamy texture contributes to the feel of the coffee once in the mouth.
At Nespresso we see crema as more than just a textural aspect of coffee; it is an integral part of the overall coffee drinking experience. Given the important role crema has in the enjoyment of a cup of Nespresso coffee, Nespresso scientists decided to collaborate with colleagues from the Nestlé Research Centre to more fully understand what factors contribute to a high quality crema.
How crema shapes perception
We first examined how the physical structure of crema affects our perception of coffee aroma. Crema is commonly understood as acting as a “lid” that quickly traps the aromatic compounds in the coffee so these can be savoured throughout the coffee consumption. The results, however, proved the opposite.
In the first minutes after extraction, crema actually helps liberate the more delicate aromas of a coffee, allowing us to perceive notes above the cup such as fruity, floral and fresh roasted. It is only as the crema settles, after some three minutes following extraction, that it functions as a seal to keep the aromas in the cup.
The amount and quality of crema also affects the in-mouth flavour perception. As expected, research showed that less crema yields a lower intensity of aromas and flavours perceived, both above the cup and in the mouth. However, beyond a certain point, increasing crema quantity does not significantly improve the perceived aroma or taste of a cup of coffee.
How crema shapes expectation
Delving deeper into the interaction between crema and the coffee tasting experience, we then examined how crema impacts not only our perception of the coffee, but also our expectations of coffee quality. The correlation between expectation and actual tasting is very important: if a coffee’s actual taste does not match our expectations, as consumers we could be easily disappointed. On the other hand, if the crema brings our expectations in accord with our actual coffee tasting experience, then our satisfaction will be increased.
Seven espressos were prepared from the same Nespresso Grand Cru coffee. While they had the same final taste, the quantity and colour of their crema varied. This was achieved through either increasing the pressure to amend the crema or by filtering to reduce it. It was found that a higher crema quantity increases the expectation of coffee smoothness and premiumness. The thicker the crema, the better the coffee quality was expected to be.
Interestingly, when evaluating the crema created by a typical cup of Nespresso coffee, consumer testers found their coffee experience enhanced, as their expectations were well matched by the sensory experience they had when drinking the coffee itself.
Advancing coffee expertise
With these first-time scientific studies on crema, Nespresso opens the door for further research on aroma sensory perception. The results of the studies have been published in scientific journals, and aspects presented by Nespresso and Nestlé scientists this September in Switzerland at Eurosense 2012. Held every two years by the European Sensory Science Society, this international conference brings together the world’s leading food scientists to explore the latest developments in sensory science and consumer research.
Research on coffee expertise
Research on coffee is central to Nespresso. We always aim to increase our understanding of our products and to find ways to ensure the highest quality of our coffees from the tree to the cup. Nespresso has a wide research network through four Nestlé Research Centres and external collaborations in coffee producing countries and in Europe.
Impact of crema on the aroma release and the in-mouth sensory perception of espresso coffee. Barron D, Pineau N, Matthey-Doret W, Ali S, Sudre J, Germain JC, Kolodziejczyk E, Pollien P, Labbe D, Jarisch C, Dugas V, Hartmann C, Folmer B, Food & Function, 2012 Sep 22; 3(9):923-30.
- Influence of foam structure on the release kinetics of volatiles from espresso coffee prior to consumption.
Dold S, Lindinger C, Kolodziejczyk E, Pollien P, Ali S, Germain JC, Perin SG, Pineau N, Folmer B, Engel KH, Barron D, Hartmann C., Journal of Agricultural and Food Chemistry, 2011 Oct 26; 59(20):11196-203.