Effect of fermentation method, roasting and conching conditions on the aroma volatiles of dark chocolate

Abstract

The combined effect of two cocoa fermentationmethods – heap and tray – and different roasting and conching conditions on aroma compounds of dark chocolate were investigated. Dynamic headspace sampling/gas chromatography-mass spectrometry (GC-MS) was used to isolate and identify aroma volatiles. Odor-active volatiles were detected and identified by gas chromatography-olfactometry/GC-MS. Fermentation method, roasting and conching conditions influenced mostly the levels of aroma volatiles identified. Principal component analysis based on a reduced data set of 16 important odorants resulted in a total variance explained by two principal components of 81% accounting for fermentationmethod, roasting and conching conditions. The levels of most important odorants were generally higher at high roasting temperature (150C) but decreased significantly (P < 0.05) with increased conching duration from 6–10 h at 80C. Roasting at high temperature (120C or 150C), coupled with short-time conching (6–8 h) or no conching, makes the difference between heap- and tray-fermented samples more pronounced