Coffee Data Science
Don’t Buy a Cheap DeLonghi Espresso Machine
A data driven review
I didn’t set out to tell you that this machine was a terrible machine. I had the opportunity to try it out, and I honestly wanted to use all my espresso knowledge to see how I could get the very best espresso out of it. I thought many people might buy this machine as an introductory espresso machine, and maybe there were a few things you could improve to make the most of it.
However, I was unable to progress, and I have now become convinced this machine won’t make good espresso. I’m convinced its design doesn’t allow for improvements, and it wastes coffee.
The DeLonghi machine, pictured here, costs about $250. It uses a pressurized portafilter, and the assumption is that you should be able to get decent espresso out of it, at least for espresso based drinks.
First, I removed the pressurized part of the portafilter. That can cover for deficiencies in the shot. To be able to understand this better, I needed the raw performance, but it turns out with or without the pressurized part, it still performs terribly. Maybe the pressurized portafilter is only to make fake crema.
While I was at it, I imaged the shower screen and the filter basket to better see how they would perform.
Using image processing, I measured the hole sizes, and I found that the shower screen has a few clusters of larger holes as does the filter basket. This means its design is inhibited from performing well.
I cleaned the machine because it was used, and the pattern on the shower screen matched what I had imaged.
Metrics of Performance
I used a few metrics based to quantify coffee extraction. I typically include taste metrics, but based on the smell of the shots, they would have all been terrible and difficult to distinguish from one another.
Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY).
Intensity Radius (IR) is defined as the radius from the origin on a control chart for TDS vs EY, so IR = sqrt( TDS² + EY²). This metric helps normalize shot performance across output yield or brew ratio.
Equipment/Technique
Coffee Grinder: Niche Zero
Coffee: La Prima Bar
Shot Preparation: Regular and Staccato
Other Equipment: Atago TDS Meter, Acaia Pyxis Scale
Shots
I pulled a few shots with some variations, and I even tried to dial in the shots. I know pre-infusion is important, so I was able to use the how water function to divert water flow (using the steam wand) for 10 seconds to give the shots some of the benefits of pre-infusion. This was planned from the beginning, and I knew I was aiming for the best shots out of the gate. This steam wand trick is something I read you could do for a Gaggia Classic.
The shots looked okay for the machine, but they were similar to my super-automatic.
From the top of the puck, the indentions from the shower screen showed where the water was coming from. Typically, looking at a puck from the top doesn’t show such clear evidence of a shower screen issue.
From TDS/EY measurements, the shots weren’t going anywhere fast. I suppose pulling a longer shot might have helped, but I’m not convinced by the channeling I saw. I have a lever machine shot just to give a comparison. All the shots were around a 1:1 ratio.
The shots were running fast, so I went finer. However, the shots still ran in a similar amount of time. I looked at the pucked from the bottom, and all I saw was slow flow around the outside ring of the filter basket. This indicates water was running through the center and channeling straight down.
I made adjustments to the shots, but it didn’t seem to impact performance. I suspect this is caused by both the shower screen and the filter basket. Whatever the case, I decided to cut my loses. If you have such a machine, I’m sorry your machine is a piece of garbage. I wonder if fixing these two things could help the machine, but that is not what one expects from $250 purchase.
It isn’t you, it’s the machine.
If you want good espresso on the cheap, don’t. For good espresso, you need good beans, a good grinder, and a good machine (in that order). There are options now to get a decent setup for close to this price (like Flair Espresso and a hand grinder), but don’t buy this DeLonghi and aim to level up if you like it. This machine could single-handily ruin your espresso experience because it might seem like you just can’t figure out how to make espresso well when it isn’t you, it’s the machine.
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Further readings of mine:
Collection of Espresso Articles