I recently upgraded from a cheap machine to the Breville home barista. However, since I bought it I've been struggling to make a good espresso.

The home barista has a pressure gauge that shows a pretty large sweet spot for making a good espresso. Below this point is under-extracted and over is obviously over-extracted. I am constantly getting over extracted coffee. I've used single and double baskets and have the same issue with both. I'm not overfilling it with coffee, have tamped everywhere from solid pressure to almost no pressure and have tried numerous grind settings on the machine to try with a coarser grind.

Unfortunately the results are the same every time - waiting 10+ seconds for an espresso coming out in drips and having a poor texture.

Any tips/ideas on steps to take to fix this?

Thanks.

Too fine a grind?

Ooops! Disregard. I didn't see the comment about adjusting the grind.

Sounds like you tried everything (coarser grind, less tamper, etc).
May be a machine problem. Wanna try posting some pictures or a video?

jboo wrote:I recently upgraded from a cheap machine to the Breville home barista. However, since I bought it I've been struggling to make a good espresso.

The home barista has a pressure gauge that shows a pretty large sweet spot for making a good espresso. Below this point is under-extracted and over is obviously over-extracted. I am constantly getting over extracted coffee.

Are you basing extraction solely upon the brew pressure gauge? That is incorrect. Low brew pressure does not necessarily imply underextraction, and overextraction does not necessarily result from high brew pressure.

If you provide more details about your machine, grinder, and coffee, it might be easier to help. (As far as I know, Breville does not make a "home barista" model.) Breville espresso machines feature preinfusion, so a 10 second delay prior to seeing the first drops is not that unreasonable.

Espresso production is basically the same thing that chemists do when they do column chromatography. There are hundreds of compounds in coffee. Some of them bind strongly to the ground coffee bean particles, some weakly. The first material that comes through a shot contains mostly compounds that are very weakly bound. As more and more solvent, in this case water, passes through the material materials that are more strongly bound begin to elute.

Two things seem to happen when roasted beans age: (1) many compounds in the coffee are destroyed by reaction with air. (2) For reasons I do not understand, the particles seem to bind less strongly to things that are absorbed on them. The deterioration also results in the need to grind finer to prevent the water from just running through.

One can notice the chromatography effect on drinking a cup of espresso that has not been stirred. There are different flavours all the way down the cup!

Impurities in the water also influence things. The really important one is bicarbonate ion. (Essentially all the other major impurities in tap water are present in higher concentration in coffee beans than in worst tap water!) There are many organic acids in ground and roasted coffee. These acids typically have pKa of about 4.8. This means that coffee with a pH of 4.8 will have most organic acids about half ionised. If the pH of the coffee were 5.8, there would be 10 times as much anion (ionised acid) as free acid. Thus pH, acidity, has a profound effect on taste. Bicarbonate is a pH buffer that tends to raise pH and thus increase anion fraction.

More alkaline water tends, however, to result in more bitter espresso, because free amines are basic and converted from alkyl ammonium salts to free amines as water becomes more alkaline. Alkaline water is less likely to extract amines in the first place.

Alkaline water also tends to result in converting insoluble acids into their anions during the espresso production process. These are more apt to end up in the espresso with alkaline water.

I am a voice crying in the wilderness, but I advocate starting with very pure water (good reverse osmosis or distilled) and adding potassium bicarbonate to it. This does not reduce Ca or Mg in the espresso because there is more Ca and Mg in the beans than in the water! What it does do is decrease the hydrogen ion concentration (raise pH of both the extracting water and of the final espresso.) Unlike relying on companies to produce bottled or municipal water with a constant composition I set the bicarbonate ion concentration myself. Furthermore the concentration does not keep changing during a session from scale deposition which removes bicarbonate so that there is less bicarbonate as the session goes along.

I keep a bottle of 10% KHCO₃ in my espresso making area. Often 100 ppm KHCO₃ is good. This involves simply adding 1.0 mL of the solution to each litre of pure water. I can add more or less to taste.

One can use NaHCO₃ too, but one can not make a 10% solution of it. I have used 5% NaHCO₃ before I started using the K salt.