I have caffeine-content question: all other factors being equal, does a long shot have more caffeine than a short one?

My specific situation is this: I have a Nespresso Essenza machine. I typically make a 4 oz shot using Nespresso's "Ristretto" capsule. Nespresso says that the "Ristretto" capsule contains 65 mg of caffeine; and the Ristretto capsule is designed to make either a .85 oz ristretto shot or a 1.35 oz espresso shot.

BTW, I am planning on buying a semi-automatic and grinder in the near future, so I'm also wondering how this issue would apply to long vs. short shots in that situation, as well as how it might apply to cafe crema vs. espresso shots.

Thanks for anyone's help.

Tim

Caffeine is water soluble. The longer the coffee is in contact with water, the more caffeine is extracted. That is why an espresso contains less caffeine than a brew or press pot. The longer steep times extract more caffeine.

I've heard that explanation before. However, I've also heard that caffeine is one of the faster dissolving molecules in coffee, and thus fully extracts into even the most under-extracted cup. If the latter is true, caffeine amount would be the same for a certain coffee dose (assuming same coffee, same roast), regardless of brew ratio (or even method).

Can anyone confirm?

Adapted from a better version of this figure espresso caffeine amount referencing Petracco, M. (1989) Physico-chemical and structural characterisation of espresso coffee brew. In: Proceedings of the 13th ASIC
Colloquium (Paipa), pp. 246±61. ASIC, Paris, France. From the Illy book as mentioned below.

x=ml, y=mg caffeine for a double ristretto, if I recall correctly. Apologies for errors and edits as sent from my phone.

So, what are the numbers on each axis?

That appears to be similar to Figure 8.4 of Illy, Viana, and Liverani, Espresso Coffee: The Science of Quality, Second Edition, 2005, who also reference Petracco, 1989, where the axes are Beverage Volume (ml) along the bottom and Cumulative Caffeine Weight (mg) along the side.

25 ml ~ 0.85 fl.oz
40 ml ~ 1.35 fl.oz.

So if the coffee and extraction parameters are similar, this suggests that the 40 ml shot has perhaps 20% more caffeine than the 25 ml shot.

Pulling that to 4 fl.oz. (~120 ml) looks like it is getting you into the saturation point. I would guess from the data presented that you're not seeing a lot more caffeine extracted than at 40 ml. (The quadratic model they fit has long since turned south.)

Hey aeclectic, Jeff, ChrisC & cannonfodder, thanks for your input. I got much better answers from you than I got from Nespresso. I'm really looking forward to using a semi-automatic machine soon. Cheers,
Tim

Something that is not mentioned here is despite the fact that an espresso normally has less caffeine than a regular cup of coffee the caffeine in an espresso is more concentrated and hits you all at once.

opother wrote:Something that is not mentioned here is despite the fact that an espresso normally has less caffeine than a regular cup of coffee the caffeine in an espresso is more concentrated and hits you all at once.

If something's hitting you all at once it's not the caffeine...
http://www.springerlink.com/content/g4204112562h13k6/