I did a little experiment, so you don’t have to, to learn exactly how each changeable variable affects the taste of espresso. Here’s what I found:

Short version: if you’re too lazy to read on: I found in general, each variable seems to under extract, or over extract the espresso in one way or another.

If you want to know the specifics, buckle up and continue on.

Equipment

Machine: Expobar Minore IV

Grinder: Baratza Sette 270wi (grind by weight model)

Basket: Pullman precision 876

Tamp: Normcore flat base

Scale: Wacaco Exagram Pro

The rules

We’re going to keep a standard recipe, but change 1 thing at a time to see what impact that has on our cups taste, which is:

Ratio: 1:2 (15 grams in, 30 grams out)

Time: 25-30 seconds roughly

Temp: 93 degrees Celsius

Pressure: 9 bar

Bean: “Ethiopia Ajere Natural” by Single O Coffee Roasters – one of the best roasters in Australia, so we’re working with quality here. Omni roast (suitable to all methods) but seems to be on the lighter side. It’s a single origin bean.

Process: Natural

Variety: Heirloom

Tasting notes: Blueberry Jam & Brown Sugar

Grind

Too fine: 15g in 30g out – 36 seconds

Taste: Disgusting! Watery, with harsh bitterness. Battery acid.

The grind was so fine it mostly choked up the machine and ran slow, however not as slow as I predicted, the pressure forced a lot of the water through a channel which resulted in the watery description

Too course: 15g in 30g out – 14 seconds

Taste: Weak and diluted, high acidity

Not terrible, but not good. It reminded me a little of pour over, much more diluted. I was picking up some pleasant flavours, but also some not so pleasant flavours and I couldn’t shake the strong lemon like acidity.

Temperature

Too cool: 85C. 15g in 30g out – 27 seconds

Taste: Pretty good! But missing something

I described this as a pretty decent shot, but more of a mild and mellow espresso, just missing something. Maybe that punch and sweetness extracted from more heat. I was picking up a Vegemite taste

Too hot: 105C. 15g in 30g out – 24 seconds

Taste: Sweetness overrun with bitterness

Compared to shot above that was pulled cooler, this one definitely produced more sweetness, but was overrun by a harsh bitterness. I think a clear indicator that you can find the right sweet spot in the middle somewhere.

Pressure

Too low: 4 bar. 15g in 30g out – 44 seconds

Taste: Not terrible. But mild and thin, no sweetness.

Obviously ran a lot slower as there wasn’t enough pressure to get through the puck quicker. The thing I noticed the most about this shot was its thin mouthfeel, and lack of crema. It didn’t really have any thickness to it. Again reminded me a little of a pour over with some nice flavours in there but overall not a great shot.

Too high: 13 bar. 15g in 30g out – 20 seconds

Taste: Weird! Unpleasant bitterness

This was the weirdest shot I tasted. It definitely was not good. Off, unpleasant, notes of bitterness, and I was picking up a really strange grassy/straw flavour

Ratio

Short/Ristretto (1:1) 15g in 15g out – 16 seconds

Taste: Good. Jammy, intense and concentrated

This was probably my favourite shot overall. It also was the first shot where I was finally starting to pick up the origins and tasting notes of the bean – jammy blueberry.

Long/Luungo (1:3) 15g in 45g out – 26 seconds

Taste: Pretty good. Soft and diluted.

Again, this is a shot I’d compare similar to a pour over. Mostly pleasant and mild, but in my opinion lacking that punch and missing something, like something is trying to get through but just can’t.

Time

Short/Ristretto (1:1) in 26 seconds. 15g in 15g out

Taste: Intense. Decent, but lacking sweetness

To be honest, I couldn’t tell too much of a difference between the 2 ristrettos, this one was pretty good as well, but lacked the sweetness that the first one had.

Long/Luungo (1:3) in 25 seconds. 15g in 55g out

Taste: Yuck. Bitter dull and bland.

I didn’t like this one. This shot was basically just diluted bitterness, I’m guessing due to the contact time of the water, and no pleasant flavours really came through at all.

I’m happy I took the time to do this experiment, and play with the variables to see for myself exactly how it affects espresso taste. I think it’s helped me learn what to change and when, and get better at dialling in to taste rather than following the traditional guidelines of the variables.

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