Influence of roasting and conching on aroma volatiles of chocolate

Abstract

The effect of different conditions of roasting and conching on the aroma volatiles of dark chocolate produced from heap-fermented Ghanaian cocoa beans was studied. Eleven dark chocolate samples including two control samples were produced with different combinations of roasting and conching conditions.Volatile compounds of the samples were isolated by dynamic headspace sampling and identified by GC-MS. The levels of most aroma compounds increased with high roasting temperature but the same were reduced as conching duration was increased from 6-8 h. Roasted unconched control sample had higher levels of most aroma compounds than the other samples. A Principal Component Analysis (PCA) Plot based on the GC-MS peak areas of aroma volatiles identified in samples explained more than 78% of the variation in the samples due to a combination of roasting and conching conditions. This indicates that both roasting and conching had an influence on the levels of aroma volatiles in the chocolate samples.The presence of some known heatgenerated compounds such as furanic compounds and a pyrrole in the unroasted control sample suggest the formation of such temperature-generated compounds during the high conching temperature of 80 "C