The Curator
Investigating how the microstructure of coffee beans evolves during the roasting process
About The Curator
The Curator are a woodroast coffee company based in Totnes, who roast specialty grade coffee beans in their bespoke Italian roaster using local and sustainable wood. We worked with The Curator to analyse their coffee beans at different stages of the roasting process usingScanning Electron Microscopy to see how their microstructure changes across the duration of the roasting process. This project was carried out as part of our fully ERDF and University of Plymouth funded Plymouth Materials Characterisation Network project.
"We were blown away by the impressive equipment in the lab...it was really amazing to be able to see the internal structural changes from the pre-roast to post-roast beans, as we're normally used to seeing just the external colour change from green to brown"
How did we do it?
At every minute during the roasting process, the roaster at The Curator removed multiple coffee beans for us to analyse - from raw beans to those that were fully roasted and ready to drink. These were brought to us at PEMC, where they were mounted onto stubs and coated in gold ready for analysis.
As we were looking at the 3D structure of these beans in the microscale, to image the coffee beans we used the secondary electron detector our JEOL IT510 LV SEM at standard working conditions for imaging.
What did we find?
We looked at these beans using the same conditions under the same instrument to make sure the results were as comparative as possible, this is called a 'comparative analysis'.
The first step of analysis was to look at the top surfaces of the beans to see how their external structure and surface textures changed during the roasting process. We found that across all the beans analysed, the top surfaces of the beans remained very similar with no clear variation in microstructure (right).
Beans in cross section
The next step of analysis was to look at the cross sections of each coffee bean to see if there were any changes in the internal structure throughout the roasting process.
We found that when looking at the raw coffee beans, their structure was very dense with few pore spaces across the cross section of the bean. Comparing this to the fully roasted, ready to drink coffee bean (left) it was clear that the fully roasted bean had abundant pore spaces likely where air has been released from the bean during the roasting process.
Coffee bean before roasting
Optimum, ready to drink
Feedback
"It has been such a pleasure to work with the team at Plymouth Electron Microscopy Centre, they have been so welcoming offering their expertise and excitement to analyse our wood roasted beans during the different stages of the wood roasting process. They invited us into the lab to analyse how the microstructure is changed during the roasting process. We were blown away by all of the impressive equipment in the lab and really enjoyed watching our beans get coated in gold! It was such a great day out and so interesting to see our coffee beans in such a different environment and zoomed in on the big screen. It was really amazing to be able to see the internal structural changes from the pre-roast to post-roast coffee beans, as we're normally used to seeing just the external colour change from green to brown during the roast."
