The hygroscopic nature of coffee grounds

The hygroscopic nature of coffee grounds

The effect of humidity on grinding coffee...

If you live in Sydney then you will have noticed how humid the climate has been recently.  Furthermore, if you happen to roast coffee you might receive a message from a friend saying:

"Hey mate. Have you ever noticed how ambient humidity seems to change coffee grounds? Not sure if it’s fascinating enough to write about but I think temperature and humidity changes coffee and coffee extract."

Many of you will know that there is a direct impact on ground coffee from ambient humidity level.  I'm going to say it again (apologies), but surface area to volume ratio is one of the key concepts from physics which has direct application in the practical world of making great coffee.  Ground coffee has a really large surface area to volume ratio and is therefore hygroscopic in nature.  It readily absorbs moisture from the surrounding air.  If ambient humidity is high then a lot of moisture is absorbed which slows down coffee extraction which can lead to burnt and bitter characters. The mitigant to this risk is that on humid days you're likely going to need to make your grind coarser.  Your mileage may vary.

I also wanted to let you know that I finally cracked the code on roasting a stock of Wilton Benitez Thermoshock processed Geisha for espresso.  It's a crazy unctuous coffee which has ridiculous mouthfeel as well as really fascinating flavour notes of marmalade, lavender and molasses.  I'll be selling it in 333 g lots and I only have four lots available... so if you're interested get in quick!

PURCHASE GESHA

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