My PhD research explored a novel roasting method for cocoa nibs, the fluidized bed roasting, and compared it with conventional roasting. The main difference between these techniques is the heat transfer method: in the conventional technique, this is mainly conductive (from the metallic surface in contact with the food), and in the novel technique, this is almost exclusively convective (from hot pressurized air). Compared with conventional roasting, the fluidized bed technique was 12 to 16 times faster, increased the porosity of cocoa nibs, and favored the formation of one of the most important kinds of Maillard reaction products: the pyrazines. Pyrazines are odor-active compounds displaying cocoa, nutty, sweet, chocolate, roasty, and earthy notes. Moreover, the fluidized bed technique favored the formation of more intense brown melanoidins.
Lastly, my thesis demonstrated that cocoa melanoidins are potential prebiotic material that improves the balance of non-pathogenic/pathogenic species in the gut.