Espresso Crema

  • DOI: 10.1002/chemv.201400062
  • Author: ChemViews Magazine
  • Published Date: 07 October 2014
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
thumbnail image: Espresso Crema

Espresso must be topped by a foamy, reddish-brown, consolidated surface layer called crema. This metastable foam with a specific lifetime of ≤ 40 min is a marker of quality for expresso.

What is the Crema?

Espresso Crema

It has been suggested that triacylglyceride, diacylglyceride, fatty acids, glycolipids, glycoproteins might be involved in formation and/or stabilization of the foam.

How is the Crema Formed?

How is the espresso crema formed

How Should the Crema Look Like?

Espresso Crema


stable, reddish-brown, pervaded by wispy, lighter stripes (tiger-skin effect)
consolidates itself even after vigorous stirring

chemical composition in ppm includes

  • ethylgujacol 1.2
  • 2-ethyl-3,5-dimethylpyrazin 0.9
  • 2-ethyl-3,6-dimethylpyrazin 0,8
  • 2,4-decadienal 0,7
  • 2,4-nonadienal < 0.5
  • methylsalicylat < 0.5
  • dimethyl trisulfide (DMTS) < 0.5
  • isovaleraldehyde < 0.5
  • α-ionon < 0.5
  • linaloole < 0.5
Espresso Crema

overextracted espresso

dark brown, hole or white spot in the middle
- too fine grind

- too much coffee powder

- too hot water temperature

- too long brewing time

- too firmly tamped filter cake

  • ethylgujacol 2.1
  • 2-ethyl-3,5-dimethylpyrazin 1.3
  • 2-ethyl-3,6-dimethylpyrazin 1.2
  • 2,4-decadienal 2.6
  • 2,4-nonadienal < 0.8
  • methylsalicylat < 0.8
  • dimethyl trisulfide (DMTS) < 0.8
  • isovaleraldehyde < 0.8
  • α-ionon < 0.8
  • linaloole < 0.8
Espresso Crema

underextracted espresso

light, thin, unstable

- too coarse grind

- too little coffee powder

- too low water temperature

- too short brewing time

- too old beans

  • ethylgujacol 0.6
  • 2-ethyl-3,5-dimethylpyrazin 0.8
  • 2-ethyl-3,6-dimethylpyrazin 0,8
  • 2,4-decadienal 0,3
  • 2,4-nonadienal < 0.3
  • methylsalicylat < 0.3
  • dimethyl trisulfide (DMTS) < 0.3
  • isovaleraldehyde < 0.3
  • α-ionon < 0.3
  • linaloole < 0.3

How Does the Crema Affect Taste?

After enjoying a cup of espresso with a good crema, one can actually still smell and taste it 20 – 30 min later.

Why is the Crema Important?

The crema prevents too rapid cooling, holds aroma volatiles back, and protects against hydrolysis.

Coffee Blends

In this article we are referring to Coffea arabica. From the over 60 Coffea species, also Coffea canephora (Coffea robusta) is used commercially.

Espresso Crema; Coffea Blends


[1] Ernesto Illy, Luciano Navarini, Neglected Food Bubbles: The Espresso Coffee Foam, Food Biophys. 2011, 6, 335–348. DOI: 10.1007/s11483-011-9220-5

[2] Klaus Roth, Espresso – A Feast for the Senses, ChemViews Mag. 2010. DOI: 10.1002/chemv.201000016

Article Views: 19510

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in


Margaret Holdridge wrote:

I love articles on anything to do with the "chemistry" of cooking. Thanks!

Tue Oct 07 15:38:12 UTC 2014

If you would like to reuse any content, in print or online, from, please contact us first for permission and consult our permission guidance prior to making your request

Follow on Facebook Follow on Twitter Follow on YouTube Follow on LinkedIn Follow on Instagram RSS Sign up for newsletters

Magazine of Chemistry Europe (16 European Chemical Societies) published by Wiley-VCH