Espresso extraction

I have been thinking about the way espresso tastes.  There is a long standing prejudice against acidic taste in coffee. I find it confusing, considering that the vast majority of bevvies that we enjoy every day are highly, sharply, and sweetly, acidic. What would a hot summer’s day be without a glass of ice cold lemonade? Every put a penny in a glass of Coke for kicks? White wine would never be the same without the fruit flavours, brought you by the delightful fruit acids present. And some say coffee is a fruit (technically, it’s a pit). Here’s the lowdown with ‘brightness’ and espresso.

Acidic and volatile aromatic compounds in coffee are extracted easily, therefore, first, in a shot of espresso -> followed by caramels (sweetness) -> then by bitter/astringent compounds. Think in terms of seconds. 20 seconds (sour) -> 25 seconds (sweet) -> 30 seconds (bitter), generally.
Acid without sweetness is called ‘sour’ or ‘sharp’. This is always underextraction. Acid with sweetness is called ‘crisp’ or ‘bright’.  It is responsible for fruit and floral impressions. This is a good thing.  It’s important to note the distinction between ‘sour’ and ‘acidic’ in our coffee tasting vocabulary. Sour is vinegar, acidic is like lemonade.  Acidity balanced with sweetness balanced with bitterness is just right. It’s what we are looking for. This is best.
Overly Acrid/bitter flavours rcome from overextraction (and sometimes stale coffee).
There is another rule of thumb.  The darker the roast, the less fruit (citric acid) remains, and the more bitter (chlorogenic acid) will be present in all shots. It gives a broader window through which to jump; it is more forgiving.
The lighter the roast, the narrower the window for balance, but the greater the potential to have a complex, expressive flavour which captures the nature of the origin. Pulling shots of lightly roasted coffee as espresso is like balancing on a knife edge.
If you can handle it.  I encourage you to try.
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