Release of phenolic compounds from fermented cocoa powder during fast heating in a novel hot plate reactor

Abstract

This article studies the release of phenolic compounds during cocoa heating under vacuum, N2, and air atmospheres, and proposes fast heating (60 °C • s−1) as a methodology that allows the release of polyphenols from fermented cocoa powder. We aim to demonstrate that gas phase transport is not the only mechanism to extract compounds of interest and that convective-type mechanisms can facilitate the process by reducing their degradation. The oxidation and transport phenomena were evaluated both in the extracted fluid and in the solid sample during the heating process. Polyphenols transport phenomena were assessed based on the fluid (chemical condensate compounds) that was collected cold with an organic solvent (methanol) in a hot plate reactor. Out of all the polyphenolic compounds present in cocoa powder, we assessed specifically the release of catechin and epicatechin. We found that high heating rates combined with vacuum or N2 favor the ejection of liquids; then, it is possible to extract compounds such as catechin—which is dissolved/entrained and transported in the ejected liquids—and avoid degradation phenomena.