🤓 Specialty Coffee’s loveable science mascot and all-round good guy Christopher Hendon
posted what you might call an AMA
in the Barista Hustle Facebook group this week prompting any and everything science-y to be thrown his way.
The following is a… distillation… of that thread 👉😉👉.
Questions are summarised in bold with Chris’ shortened response is beneath. Direct quotes are in quotation marks.
What’s the situation with transgenic agriculture?
You could try to modify a coffee leaf to resist something like rust (roya), but the leaf is also where the delicate process of photosynthesis happens, and you don’t want to screw up photosynthesis. It’s too early to speculate whether we’re skilled enough to avoid long term problems.
Coffee is hygroscopic (soaks up water). Is this why parameters change during a bar shift?
Every small variable in coffee seems to matter, and it’s nearly impossible to separate humidity from other variables like temperature. There’s only one way to find out: do a proper experiment.
When is best to consume a coffee after roasting in relation to ageing, degassing, and oxidation?
CO2 continuously leeches out from the dense coffee cells from the moment it’s created during roasting. CO2 could be dissolved into brewing water, reducing the pH - whether this tastes good to you is up to you. Same goes for all the other compounds that are slowly escaping the bean.
Oxidation is a separate issue. It will happen, but only if you store the coffee in an environment with plenty of oxygen. Lowering the storage temperature will significantly slow this effect.
Ageing is a process which can see the reaction of fats and other unsaturated hydrocarbons, and oxygen rich molecules, undergo chemical reaction which yields new molecules that could only be obtained with time (ie. very slow).
All together, this is very anecdotal and personal. It’s best for you to test and taste and form your own opinions.
When roasting, does the temperature or the time matter more for chemical reactions?
Hitting a certain temperature is the key for most reactions, but they don’t necessarily happen straight away. Once you’re at or above that temperature, applying more heat will make that reaction happen faster.
Why don’t all grinders use the same number scale?
There’s way too many variables to make this work. Also, “It’s phenomenal how useless the grinder settings are”.
Can we quantify the chemicals in a coffee that are making specific flavours?
We could use high level analytical techniques. These might be useful.
It’s hard to tell whether the biological response you are having is due to the presence of one molecule, or two acting together, or 30. You can definitely draw some fun correlations between flavour descriptors and chemistry.
Has there been any research/thought on the importance of dissolved oxygen and its impact on brewing?
“No idea why dissolved oxygen would make any difference given it is non-reactive with most things. More importantly, its content in average water is like, <1 ppm.”
A big thanks to Chris for being a knowledgable, generous, and humorous host.