Uploaded June 2026 | Updated September 2026, 2 hours ago
I've made a cup of coffee that's somehow hot and cold at the same time.
The secret is gellan gum, a thickener produced by bacteria originally discovered in pond scum. It has an unusual property called thixotropy, which means it stays thick when still but becomes liquid when disturbed.
After plenty of trial and error, I finally cracked a reliable recipe using frozen coffee concentrate. The result is a drink where hot and cold coffee can coexist not just in the same glass, but in the same sip.
Now it's ready for the ultimate test: serving it to James Hoffmann.
I've made a cup of coffee that's somehow hot and cold at the same time.
The secret is gellan gum, a thickener produced by bacteria originally discovered in pond scum. It has an unusual property called thixotropy, which means it stays thick when still but becomes liquid when disturbed.
After plenty of trial and error, I finally cracked a reliable recipe using frozen coffee concentrate. The result is a drink where hot and cold coffee can coexist not just in the same glass, but in the same sip.
Now it's ready for the ultimate test: serving it to James Hoffmann.
