Prufrocker: The Blog

The short history of bitterness, acidity and sweetness

I was invited to Brno in the Czech Rep. for the launch of Industra Coffee and there was a day of speeches, workshops and BMX and Calligraphy. Here is a summary of the speech I gave.

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Industry Coffee, Brno, Czech Republic.

I was invited to Brno in the Czech Rep. last weekend for the launch of Industra Coffee and there was a day of speeches, workshops and BMX and Calligraphy. Here is a summary of the speech I gave. It’s called “The short history of bitterness, acidity and sweetness.”


My first adult coffee was a latte with two sugars from a family Newtown roaster and a secret blend. In my first share house I was awoken every morning by my house mate’s local Mocha-Java blend hurtling around a little spice grinder followed by a gurgling stove top finale. The language we used to describe the coffee was very traditional and rather masculine. Bold, swarthy, potent, robust, intense. We were enthused but it sure was BITTER.

SWEETNESS was never mentioned in our conversations.

Here is a quick explanation of why:

The Very Short History of Roasting for the SECOND WAVE:
Cheap defective coffee could be improved by increased evaporation of acids from darker roasting. If coffee is strip-picked and processed with a minimum of quality controls there will be a big mixture of underripe and over ripe cherry. The underripe component will be very high in sour tasting citric acid. The overripe component is likely to have higher levels of sour and ferment tasting acetic acid. This is the acid we call vinegar. Acetic acid is also produced during the fermentation stage in processing and actually greatly increases during roasting right up until the medium roast level, up to 25 times according to This was then significantly reduced with darker roasting through evaporation. The reduction in sourness was traded in for an increase in bitterness as mildly bitter chlorogenic acid breaks down into very bitter and astringent quinic acid (the acid found in malaria pills and tonic water) and cafeic acid (linked to anti-cancer properties). This high level of bitterness could be balanced by the natural sweetness of milk and the creaminess of steamed milk would restore smoothness to very astringent espressos. Milk would also help to disguise flavour taints from past crop coffee through dilution if dark roasting wasn’t sufficient to eradicate these inconsistencies. They needed very big cups in the second wave.


I moved to London and got a job as a trainee with Gwilym Davies and Jorge Fernandez, co-managers of Monmouth at the time. At my job interview, Jorge asked me what my favourite pasta was and I said Gnocci. Years later Gwilym told me that’s what got me the job.


High times with triple ristrettos (quadruple really, 30g doses), Fernandez and Wells and the UK’s first Synesso. Think dry hopping and craft beer and you will understand what was going on at F and W. They were balancing bitterness with acidity. And they were attempting to feature enzymatic and sugar browning aromas in preference to dry distillation aromas. Dry distillation aromas seem to become more apparent at higher extraction levels or if you aspirate strong shots. By using lots of coffee, they were bottling up a huge amount of aromatics into each cup but were intentionally taking a good deal less out of the cake. By all reports this was a global phenomena. US West coast was upping the doses, like wise down under. This was direct-action to combat roastiness.

(Ben Kaminsky observed in his recent brewing classes that roasty flavours are masked at high concentrations above 10% TDS. He pointed out however if you cup espresso roasts considered to be lightly roasted at around 60g/L they are noticeably roasty.) So extra coffee was the way forward for us at the time as we weren’t well enough connected with roasters to have input on batch profiles like we can now. Nor did we have the cupping skills or terminology to even identify or articulate what roasty flavours were.


Gwilym is on the carts reading Scott Rao and Jim Seven and he gives me a job after my semi retirement from amateur punk music.
Not including Lungo.


Improved Barista skill with greatly refined albeit estimated dosing techniques like (NSEW and Stockfleths) help increase consistency. An increased sensitivity to machinery and the beginnings of a scientific ethos of trial and error emerges.

Square Mile start roasting in East London and as well as putting a welcomed roast date on the bag Anette and James become a hub of knowledge, inspiration and a source of clean sweet coffee.


‘Just a bloke on a boat’ takes the WBC

Barista Jessie Fay becomes convinced the groups on the lever machine aren’t calibrated, and feeling the grind-on-demand doser isn’t accurate, she starts weighing every single dose and yield to prove it to us. (We could have used a Scace 2 looking back. Well Rome wasn’t built in a day.) Weighing coffee doses wasn’t something new but realising the simple solution to yield variations Jessie has hit upon, weighing every dose  and yield (more than 50 broken scales later) becomes standard practice at Prufrock. This was something new.

The Penny University with Square Mile.
A journey with brewed coffee  highlights to us the importance of recipe – we transfer what we learn across to espresso.


Refractometry implemented at new Prufrock Leather Lane and we start to use an RO system. The combination of much softer water and 20% extraction yield hard limit type grinders and still relatively high doses and our shots are demonstrated to be consistently under extracted. The espresso isn’t as SWEET as we want it but now we know it. And we know it isn’t as BITTER as it used to be. It’s just tasting a bit sour sometimes and missing the body we were used to from all those triple rizzies.

We start dropping the dose again and grinding finer.

We switch to 18g VST baskets and start lengthening our shots which increases sweetness. We adjust our espresso brew formula to 55% down from the 66% we used to use.


Increased collaboration with Nuova Simonelli and the use of a remarkably temperature stable T3 espresso machine helps us understand optimal extraction targets and Gwilym begins to explore grind morphology and size distribution on the Mythos project.


Along side refractometry we place renewed emphasis on objectively assessing taste.

The daily ‘online’ dialling in journal is made available to students on our courses, our suppliers and various coffee people that have a collaborative spirit (an idea given to us by Coffee Mania in Moscow).

Ben Kaminsky gets his coffee shots on an EK grinder to 22% extraction yield. He is fining up to take it higher and he states “sweetness only goes up from here”.

Petra Vesela sensory judge from the WBC final in Melbourne holds sensory calibrations with our senior baristas and our dialling-in journal becomes an empirical resource in ‘training the business’ (J.Hoffmann), necessary in case you lose some beloved staff…

November 2013
Petra Streleka, former Prufrock barista and Adam Obratil, former Taylor Street Barista set up in an arts collaborative in Brno calling themselves Industra Coffee.  Petra describes this environment as a “Business Incubator”.

9:30am November 22nd 2013

Opening Day Industra Coffee
Whilst dialling in Adam Obratil asks me, “Should we serve Square Mile’s Salaca Or should we serve this fruity bomb?” referring to the Recuerdo Nicaraguan Maracaturra hybrid. This is a seachange from my early communications in coffee.

This cafe is a summit for me in the third wave. Great equipment. Real empowerment from dynamic, sociable owners that are baristas and voracious researchers of coffee. They have a T3 and an EK grinder, an RO system and lots of training. They have Villabos on the menu which is wind resistant and more suited to unseasonal weather and life at very high altitude in a changing climate. They’ve got Jara from Double shot in Prague at their party who sold out of Los Lajones Bamboo Geisha at 2500m in two hours (leaf-rust free zone?) and Taylor St legend Dominik Janda helping on the brew bar. They sell coffee by variety and they haven’t stopped making drinks on their opening day for the last 8 hours and their coffee is still less than the price of a pint. They’re in a Czech Icecream factory that is still operational. Their coffee is ripe. Their lives are sweet.