How does the grinder affect the taste of espresso? [moved from Quebec board]
Excuse my ignorance, but how does the grinder affect the taste and how much?
I use a cheap grinder for my drip coffee and my cheap espresso machine. I get much better results than anything pre-ground. I would in fact argue that cheap whole beans ground on a simple grinder is better that any ground coffee regardless of price.
I am however curious to know how much more I could extract with a better grinder.
Coffee is said to lose about half its aroma and flavour-producing compounds within 48 to 72 hours of grinding. And the process starts within 15 or 20 minutes. That's why fresh ground, even with an inadequate grinder, almost always gives you better results than preground from a professional grinder.
The main problem with inexpensive grinders, especially for espresso, is inconsistency. A whirly blade grinder produces everything from dust to chunks. The dust overextracts (harsh, bitter coffee), the chunks underextract (weak, sour coffee).
Uneven grind also creates waterflow problems like channelling in the portafilter, resulting in uneven extraction. It's not just a question of grind, either: even properly ground coffee needs to be tamped to avoid these problems.
Uneven grind also affects crema production, as crema is highly dependent on the extraction of oils, proteins and sugars from the grounds. Less than optimal extraction = less crema.