Why does my roast and espresso taste bitter?

So yesterday I ground up my coffee, I ground it to extract 60ml espresso over 20 seconds. There might be a more technical way of phrasing that, but until I discover it I will use that.

As expected from the appearance there were a few beans which had been over roasted, whilst it was drinkable, it was very bitter, had I bought it from a cafe I'd have been disappointed.

I was desperate to find a reason that perhaps it wasn't just my roast, I re-checked the grinder and all was fine, I pulled another shot, same taste, so I admitted defeat. I was able to comfort myself with the fact it was my first roast, and I think in the circumstances (no proper equipment, experience or mentoring) I'd done alright. I know, I know, a bad workman always blames his saucepans..

So I journeyed online to educate myself further on what causes and how you can prevent bitter tasting coffee. Here's what I found..

Up until recently there hadn't been much research done into what makes coffee bitter, but as peoples passion for the drink has grown and coffee is more popular than ever around the globe people have taken interest, they want to know everything there is to know about this wonderful common man's gold.

Dr Thomas Hofmann, from the Technical University of Munich has a PhD in food chemistry and molecular sensory science and I imagine Heston Blumenthal's mobile number. In his initial lab research he found that caffeine, often considered the guilty chemical, only makes up for 15% of the coffee's bitterness, noting that levels of the bitter tasting chemicals were just as high in decaffeinated brews.

He puts the bitterness down to the roasting and extraction; he trained a panel of tasters to taste and put in order levels of bitterness, through this panels work they have been able to deduce that the longer a coffee is roasted for the harsher the taste shall be, roasting a bean into the second crack will produce in coffee well suited for espresso but also much more likely to be bitter.

There are two compounds that he puts this bitter taste down to; Chlorogenic Acid Lactones (CAL) and Phenylindanes (PHL). Neither of which can be found in unroasted green beans. CAL is made up of 10 chemicals which can be found in Light - Medium roasts. PHL is found in Dark espresso roasts, it is this compound that when added to the CAL compounds produced the harsher taste.

He goes on however to say the extraction will also have a large impact on the taste, I don't think we need PhDs in food chemistry to say that an espresso machine will produce a fuller flavour and to some a more bitter coffee than a french press or a filter. He does explain though that this is due to the fact that both the CAL and PHL are extremely heat sensitive, and so the high heat levels of an espresso group and the pressure emphasise the flavour of these bitter compounds.

His research now is extending to if it is possible through alternative harvest or washing methods you can reduce the presence of these chemicals later in the process. I wish him luck with his work, however hope he never does find an answer. This battle between the natural occurring chemicals and the roasters and baristas is what drives me to be in this business.

Finding the perfect balance between roast time, temperature, grind density and extraction is the art of our work.

Roast #1 "Tabaconas Valley"

Today my first kilo of green beans arrived, I spent a few days researching which bean was going to be my first, it's hard to know what you are looking for when you are stumbling around the web, but when I saw these beans I was fairly certain they'd be a good starting place.

These beans are from North Peru, in the Tabaconas Valley, due to deforestation in the area there are few places left for native wildlife to live, many of these birds and other creatures have now migrated to the coffee plantations. So not only on top of the already excellent ethical attributes of the plantation itself this coffee also has environmental benefits that are high above a standard "eco-friendly" coffee.

Onto the roasting..

125g Green Beans

I decided to start with 125grams, I used an enamel pan, hopefully soon to be replaced with a cast iron one. I pre-heated the pan on a low heat, next time this will be done on an even lower flame.

After a minute and a half I tipped in the beans and was surprised as to how quickly they began to brown. I realised it was to hot quickly, but was able to pick out the first few beans to be burnt.

"The First Crack"

I only learnt this term yesterday, the first crack is the first time you could stop roasting, this will give a very mild roast. It sounds like popcorn popping rather than a cracking noise.

It's at this point the smoke starts also, which is why I had a window open and the extractor on.

The smoke had a wonderful smell, less of coffee than you'd expect, more of roasting nuts. It's the kind of smell you might expect more at a christmas market than through a kitchen window of a city centre flat.

I decided to end my roast at 12 minutes, somewhere in the middle of the 10 - 14 minute suggestions I had seen online in blogs and youtube videos. I followed advice and removed the beans from the pan as quickly as possible and placed them in a sieve above the sink to cool and could toss and shake to remove the chaff.

After 2 minutes sitting in the sieve I put the beans in a bowl and tossed with my fingers to remove more of the chaff.

I'll now leave for 2-3 days before grinding and brewing. I'll be sure to report the flavour!