Chilled portafilters

Berg Wu won the WBC with chilled portafilters. What do you think? Has anyone tried it?

2016 WBC regulations state the machine will be set between 90.5°C and 96°C - I assumed cooling the portafilters was a way to ensure a lower brew water temp?

He says it was to keep the espresso from being reheated after extraction by the bottom of the basket & the spouts because his coffee had lots of delicate aromas that dissappear very quickly when heated.

For reference:

It sounds wanky, i think anything that comes out of WBC needs to be taken with a grain of salt (so to speak!).

I suspect the idea that espresso is ‘reheated’ by the bottom of the basket and sprouts is simply that - an idea.

Same goes for the suggestion that some delicate aromas could be preserved by cooling the PF. I would be surprised if statistically significant blind testing confirmed this.

If your brew water is, say 93°C, through the process of kinetics, advection, dissolution, diffusion, and a whole bunch of other physics shit that’ll make your eyes go dizzy, the temperature of the espresso emerging from the bottom of the basket will lose around 7°C, so you’d have espresso at 87°C before it hits the spouts. Those spouts, if left in the group head, will be under the brew water temperature, but not by much - it very much depends on the ambient temperature. But the spout is below the basket and group head, so you’ll lose a little more heat too, so you could argue that perhaps the spouts are around 90°C - but I’d argue that’d be at most. Here again the process of cooling begins again - the initial espresso will cool down the spout, and the cooling will only continue as more espresso moves down the spout.

The bottom of the portafilter wouldn’t reheat the espresso, the espresso would cool down the spout. But if you start with a cold spout, then the espresso would cool down - and I think that’s the effect Berg got, where the floral aspects of his espresso became more apparent.

Cooling down the espresso rings true to me. Dialing in and tasting in a 6oz room temp Capp cup (as per Pergers Reddit AMA suggestions) gives a tastier and clearer picture of the espresso in my opinion. Especially helpful when you need to taste shots quickly and don’t have time to cool them down. It would make some sense if the espresso tasted better simply because it was cooler upon drinking.

If the espresso is cooling the spout, then the spout is most certainly heating the espresso (the definition of “heat” being, essentially, energy which is transferred).

It’s worth remembering that the espresso hitting the spout is not always at 87°C (although it might be at some point during the pour), because it varies throughout the shot. If the spout is at 90°C initially, it will transfer heat to the espresso up until the point at which they are at the same temperature (assuming this happens). Very hard to model this accurately.

As for what effect cooling the PF might have on the espresso, my thoughts are aligned with @Arnhem_Coffee_Roaste and @nathanderuvo - would there be any significant change in the composition of the espresso, or is it just that taste perception is influenced by temperature?

I reckon the water would lose significantly more heat as soon as it leaves the head (obviously depending on how cool the portafilters are), and this should affect the solubility of compounds in the coffee.

This year machines were set to 93.4°C

Thanks Vadym! Out of curiosity, were competitors allowed to change them for their own routines?

Great thoughts so far! Is anybody with a super delicate floral coffee willing to do the comparitive taste taste?

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I’m intrigued enough to experiment with it this week on my test rig. If anything of noteworthiness occurs I shall share.

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Awesome! Looking forward to hearing what you come up with.

I’ve always kept the portafilters out of the machine in my shop. Never had any issues with consistency or quality, but one of the most frequent questions asked by coffee professionals has always been “Aren’t you worried about the portafilters being cold?”

Hey Josh. Under WBC Rules competitors are not allowed to modify the equipment provided. that includes changing head temperatures. :slight_smile:

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Good to know, thanks Boris! I wonder if that will change sometime soon, especially now. It would be very interesting if they allowed temperature and pressure adjustments next year…

Portafilter is cooler, therefore ground coffee going into the portafilter will not begin to warm as it would if the portafilter was warm from the machine and will change rate of extraction.
The tips being cooler may help to cool espesso before it hits the cup for easier tasting by judges.

wouldn’t it be better to pull the cups out of a chiller rather than chilling the tips of the portafilter? if it’s about cooling the espresso I feel like a cold cup will be more effective no?

I doubt it for many years to be honest. The comp has been tightening up on equipment (cue only Mahlkonig grinders) and the logistics in changing pressure and temp in between every run through.

So I’ve completed my less-than-scientific experiment with chilled baskets and entire portafilters. I tried freezing them in addition to simply chilling them in a refrigerator. All tests were allowed a minimum “soak” time of two hours although I found that, for the baskets alone, 10 minutes in the freezer was more than sufficient.

And the results?
Insignificant change in the final cup. No better and no worse than dropping the brew temp at the boiler. If anything, it adds to the routine and, therefore, I’ll have to dismiss it as a viable “shopworthy” change to our technique.