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  • QA 210
    Question:
    Does espresso coffee contain less caffeine than traditional brews?
    Background:
    Is it true that espresso coffee contains less caffeine than the American (coffee) as a result of the way it is percolated?
    Asked by:
    Consumer - Mexico
    Answer:

    Yes, in the sense that the espresso process releases less caffeine than do the traditional brewing methods.

    To clarify, the following is partly based on the excellent publication 'Espresso Coffee - The Chemistry of Quality' - edited by Andrea Illy and Rinantonio Viani, and on information from other industry experts. *

    • Although caffeine is very soluble in hot water, maximum extraction from the cell structure is only obtained by percolation (brewing) methods that maintain lengthy contact between hot water and coffee grounds.
    • The extraction time for espresso is considerably less than for traditional brewing methods.
    • Data suggest that as a result the extraction or release of caffeine from coffee grounds is incomplete in espresso, due to the short time available with the espresso method to extract caffeine from the cellular structure of the coffee grounds.
    • However, the function for caffeine extraction is not straight but is an exponential regression, meaning it starts with a fast release and then the release slows down dramatically; i.e. the main caffeine amount will be extracted quickly and only relatively small amounts will be extracted by prolonging the brew.
    • Consequently, compared to other popular brewing methods, the caffeine concentration in espresso is below what is found in brewed Roast and Ground coffee (R&G). However, the main difference in caffeine content is principally due to the quantity of the drink, i.e. the cup size, rather than to the type of extraction. Obviously precise measurements will vary depending on the cup size and the blend composition of the different brews.

    NB: Although the espresso process accentuates many distinct flavours and aromas found in the coffee bean (as stated in sections 12.09.04/05 of the Coffee Guide), the authors also point out that caffeine has to be extracted from within individual cells. This does not happen easily in very short percolation processes. It is therefore worth pointing out also that, contrary to popular belief, the 'kick' associated with certain types of espresso (like 'ristretto' for example **) is not due to additional caffeine extraction but rather to a higher concentration of flavour compounds.

    * ISBN 0-12-370670-X of Academia Press Ltd, 24-28 Oval Road, London NW1 7DX

    ** Ristretto (also called a "corto") is a very "short" shot of espresso coffee. Originally this meant pulling a hand press faster than usual whilst using a smaller amount of water than for a regular shot of espresso. Since less water came in contact with the grinds for a shorter time the caffeine extracted in reduced ratio to the flavourful coffee oils. The resultant shot could be described as bolder, fuller, with more body and less bitterness. All of these flavours are usually attributed to espresso in general, but are more pronounced in ristretto. Because of this exaggerated flavour, ristretto is often preferred by espresso coffee lovers. Today, with the hand press out of favor and modern automated machines generally less controllable, ristretto just means using less water; a normal (double) espresso shot is typically around 60 ml (2 fl oz), while a (double) ristretto is typically 45 ml (1-1.5 fl oz). Quote adapted from Wikipedia - www.wikipedia.org

    Posted 15 January 2009
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