Did anybody try that method? I just used an ice cube, the result was interesting (a bit closer to espresso in caffes which use flat burr grinders and less similar to the normal taste of my conical Niche, plus more chocolate notes). Even though I took out the ice cube immediately after brewing, most of it melted (my brewing is longer because of using the ramp down profile), slightly turning my espresso into americano, haha!

You can find these balls on Amazon by searching "stainless steel ice ball" or "whiskey stone". There are 2.5 and 4 cm diameter balls (I believe, we need 4 cm).

Stainless steel cubes can be used too:
A comment below the last video:

Yeah it was quite interesting. I heard/saw the cold slows down the loss of some flavour notes otherwise lost due to heat and I guess time in pulling a standard shot.

It did preserve some notes I did not pick up as a standard shot, and it was smoother and creamier mouthfeel.

while this method actually ends up having combination of extra chilled droplets (direct contact to ball) and hotter droplets (flows above the direct contact liquid), what it ends up doing is compacting flavor (molecules expands as it heats up).

on that compacted flavor and vs tongue sensitivity with liquid closer to body temp..

doesnt it mean everyone drinking too hot of a shot such that the tongue can no longer discern flavor and therefore we should slightly wait and let cool the espresso before taste testing?

wouldnt that also mean if the espresso taste bad when cold means those flavors are actually there but not noticeable by ur tongue when its too hot because the molecules are too spread out and thin ultimately implying that the pulled shot was bad?

I always keep my cups in the fridge, otherwise the espresso is so hot that I can feel the hotness more than the taste of the coffee. At first I thought I was the only one doing this, but then I found a video on YouTube where it was advised to use chilled cups. I absolutely don't understand those who heat the cups on top of the machine, because this only exacerbates the problem. However, if you use a frozen ball, then it is probably better to heat the cups so that the drink is not completely cold.

I wonder if the material makes any difference. I'm thinking of buying steel or granite balls.

Well espresso will degrade if you let if sit for too long. And too hot of a drink will mute flavours as we know from making pourover.

These two where the reasons why I stopped preheating my cups and use thick porcelain for espresso. After my espresso is done it takes around 30-40s extra for me to have it at a warmish perfect drinking temperature which does a lot of what this technique covers.

iyayy wrote:doesnt it mean everyone drinking too hot of a shot such that the tongue can no longer discern flavor and therefore we should slightly wait and let cool the espresso before taste testing?

wouldnt that also mean if the espresso taste bad when cold means those flavors are actually there but not noticeable by ur tongue when its too hot...

Yes and yes.

Could just be me, but rapid-fire jargon has a suffocating effect on the logic and reasoning centers of my brain. There's a tendency to just let it slide, however, "volatile compounds"?? I brew with water around 200F, using beans that were roasted to over 420F...

I see at least three things going on:
1) It has already been pointed out that our sense of taste is very temperature sensitive. I saw no mention/reassurance that the samples were temperature equalized. If they're not within a few degrees of each other, all bets are off IMHO.
2) The surface area of the brew is significantly expanded as it coats the ball/cube/whatever. That provides a much shorter path for gasses to escape the liquid. I'm a huge fan of that, as the less carbon dioxide in my cup the better.
3) The coffee passing over the stainless-steel surface may react in a manner similar to the not-fully-established effect stainless steel has with onions and garlic. There might be yet other reactions from granite, copper, mithril, adamantium, or vibranium.

At least for pour over, I have seen a surprisingly big effect, with samples ±1C from each other. There's something happening unrelated to drinking temperature. I'd welcome more empirical comments - it's not very difficult to try it

Update: so a quick test with 2 consecutive shots, second one with a 2" stainless ball in the cup dropped to 31C/88F - way below my preferred drinking temperature. The first shot was sitting around a still somewhat pleasant 38C/100F.. After pouring it into a third cup the shots were within 0.5/1F from each other. It feels more challenging to compare shots than pour over, but there was a big taste difference. Could it be due to shot-to-shot variation? Maybe, but it sure tasted like they were dialed in differently. Preferred the regular shot that wasn't chilled rapidly.

I don't think I've got enough room to place the stainless ball inside a strainer on top of the cup, but would recommend that for those who do. Not a fan of cold espresso.

How about holding a spoon upside-down in the stream before it hits the cup? That would significantly increase the surface area of the espresso and (perhaps) help it shed more CO2 from the shot - without over-cooling it too much.

Well I found a cocktail strainer and ramekin combo that fit, keeping the stainless ball above the level of liquid. That cooled the shot down to 41C/106F - better, but still on the low side for my preferences. This time I was able to match a regular shot within 0.5F. Medium instead of light roast, still preferred the regular shot.

Edit: another trial, dark roast and room temperature stainless ball. Couldn't discern any difference between the shots, I don't think surface area or very limited cooling has much if any effect. Of course, these are just one-offs, would be nice to read other people's impressions. That said, this methods doesn't appeal nearly as much to me for espresso as for pour over - because the small amount of liquid easily drops too low in temperature.