What an adventure. Today I (unintentionally) came to the rescue of a coffee shop (which had better remain nameless). The problem? Espresso machine pulling shots too short (ie: not enough water running through the coffee.) It was also flashing its lights rather pathetically, hissing worryingly when it refilled and also beginning to leak hot water out of the side of the machine!
Pressure and temperature dials seemed normal and there was no obvious cause of the leak. So, I tried to reprogram it to increase the volume of water going through the coffee. No joy. The espresso was just dripping out, incredibly thick and black and sludgey, and a double shot took over two minutes to pour. It tasted vile and coated the roof of your mouth like bitter tar.
So I thought, maybe it’s just ground too finely. I adjusted the grind – it was very finely ground, like icing sugar, but seemed to be clumping together too. Even turning the grinder to its most coarse setting didn’t improve the espresso, so I turned it back again and ground some more in case it was a one-off blip. It was no anomaly; the second batch resulted in the grinder getting blocked as well and I had to poke the stuff out with the end of a spoon. So we decided to give the machines the benefit of the doubt, and tried to pull a shot using decaf espresso from another grinder. This shot worked perfectly!!
The Doctor’s diagnosis?
REALLY terrible coffee!
The decaf shot was what gave it away. There was nothing wrong with the espresso machine, it was the coffee going in to it that was causing the problems. On closer inspection, it was roasted really, really darkly. This picture doesn’t do it justice, but next to the decaf espresso, the beans looked black and very shiny. Rubbing ground coffee between my fingers felt really greasy – a sign of very low quality coffee (higher quality arabica has less oil content). The fact that it was blocking the grinder tells me exactly how greasy it was – coffee should not do that! And even very very finely ground coffee should never be so thick as to withstand the espresso machine pushing water through under 15 atmospheres of pressure.
In the end, we just had to throw the beans away. A different blend of espresso roasted by another company but made in the same grinder and with the same espresso machine, worked fine and poured a nice shot. The roast can make A LOT of difference!
Here is the bag of machine-breaking beans, just in case you were wondering. Take note of the roaster’s logo.