Acidity and Bitterness - Alan Lobb
Last week a couple of us were fortunate enough to spend 2 days in the company of Ana and Carlos of Mio Coffee at their premises in London talking about Acidity and Bitterness as well as the Chemistry of Roasting. Mio is a coffee farm in Monte Santo de Minas, Brazil, that exports, imports, stores, and sells coffee. Their overseas HQ is in London where we visited, and they are our main supplier for our flagship coffees; Brazil Mio Peaberry and Gunpowder Blend.
The talks were driven by Veronica and Fabiana who are clearly experts in their field and we learned a lot of things about our palates.
Acidity in coffee, like many things in life, is good in moderation. We will not try to explain all the technical terms and thoughts that were shared during the day but a couple of things that we learned can be summarised.
Acetic acid in not good. If you want your coffee to taste of day old fish and chip wrappers - salty, vinegary - then acetic acid is your bag.
Malic acid -found in apples - is surprisingly good! Malic acid enhances the fruitiness and we'll try to crank up the malic acids in our future roasts and coffee choices.
Acids in general are produced during roasting - reaching a peak the longer and higher you roast your coffee.
Everyone is different when it comes to susceptibility to bitterness. Its not you - its your genes. So, like everything else in life until you are around 30 years old, you can blame your parents if coffee tastes bitter.
For more information read about the PTC test. This taught us that one of us is not super-sensitive to bitterness. Many others could not tolerate it.
The caffeine taste test was also an interesting one to do. Again, one of us could happily drink the strongest caffeine solution - others could barely swallow the least strongest. Warning - do not try the caffeine test at home kidz! Only taste caffeine in solution under strict supervision - or at least with a gallon of water as your solvent.
So, overall - what did we take away from the Acidity and Bitterness? Well, both these tastes are important in the overall coffee experience. We were blown away by the impact that malic acid can have in enhancing the natural fruit, berry, and citrus flavours in a bean. Both are manageable and controllable - through roasting, selection, processing and brewing. Both act as enhancers of the nuances and natural flavours that we want to see in our specialty coffees. But a tasters experience of both is highly subjective. In the tests - one of us identified the exact acid in each and "fell out of the acid tree and hit every branch on the way down". The other of us couldn't hit the right acid tree with a banjo. And thus it doesn’t really matter what we say - it's you that will have your own preferences, likes, dislikes and baselines against which all coffees will compete.
Chemistry of Coffee Roasting - Lewis Whitworth
Around the table sat a coffee roasting nerds keen to learn Veronica's science driven approach to roasting. Whilst we've got a pool of shared information about coffee roasting on social media, youtube videos, blogs, and veterans in the industry, to have something more rigorous with a theoretical and practical element certainly developed all our skills as roasters.
We went straight back to basics, understanding exactly what coffee seeds are; their biochemical makeup, and the radical changes that occur once heat is applied. We looked at the chemistry makeup of green coffee seeds including the contained compounds, carbohydrates, proteins, fats, water, caffeine, cellulose matrix and many more. Then we explored how these compounds change, which ones disappear, and totally new compounds that are produced once the coffee is roasted. We also learned which of these compounds like certain types of acid, like malic acid, yields a distinct desirable crisp apple acidity.
Whilst roast colour is often a prevailing standard for coffee roasters to follow when seeing how well developed, our roast is, as well as when to finish a roast, Veronica put forward another factor which apparently is just as important; roasting temperature! Whilst this claim challenged all of us at the table, she underpinned this with the latest studies and first hand microscopic coffee bean cut out examples, to demonstrate how how crucial temperature is. Going forward we'll certainly be basing our roast development on temperature as most as roast colour!
After all of the in-depth theory, we put it to the test! Veronica kindly setup a cupping session to demonstrate the taste difference between a well roasted, over developed, underdeveloped and baked coffees, and how different roast profiles can yield undesirable characteristics. Lead by Veronica is a qualified Q-grader, took the cupping experience to professional levels; the timing, weight of coffee, exact temperature, quality of water, and just the overall attention to detail. We were left with precise answers on why the coffee tasted the way it did.
Afterwards we used the Ikawa sample roaster, and tested different roast profiles on the same coffee to see the changes first hand. Not only could you smell it the difference, but we were paying close attention to colour changes as well. This was more to see how even the slightest change at one phase of the roast, lays the foundation for the next phase of roast development, and how different coffees require unique roast profile, given they redpond to heat very differently.
A big thanks to Veronica, Ana, Fabiana, Carlos and everyone at Mio for hosting a deep dive into some fundamentals of true specialty coffee! We can't rate these guys enough - https://mio.cafe/
