There isn’t an easy way to build a playlist, at least I haven’t found one. This is the next best thing, links to pages that gather all the episodes on selected specific topics. I hope to keep adding to these.
Bread
All of the micro-episodes on the history of wheat and bread, originally broadcast as part of the Dogs Days of Podcasting challenge
Coffee
Episodes have featured coffee culture, coffee history, coffee economics and even coffee taxonomy. But not how to brew the best cup, because some things are sacred.
Philosophy
Questions of taste, good taste, ethics, and other things that might reasonably be thought of as philosophical in nature.
Seeds and breeding
Gathering together the episodes that deal with seeds, plant breeding and the need to conserve and use agricultural biodiversity.