Inline roasting hyphenated with gas chromatography–mass spectrometry as an innovative approach for assessment of cocoa fermentation quality and aroma formation potential

• Aroma formation potential of unroasted cocoa beans varies strongly.
• Aldehydes, pyrazines, aldehyde/amyl alcohol and TMP/TrMP reflect cocoa roasting degree.
• In-line roasting can be used to predict aroma formation during standard roasting.

Today, the cocoa industry is in great need of faster and robust analytical techniques to objectively assess incoming cocoa quality. In this work, inline roasting hyphenated with a cooled injection system coupled to a gas chromatograph–mass spectrometer (ILR-CIS-GC–MS) has been explored for the first time to assess fermentation quality and/or overall aroma formation potential of cocoa. This innovative approach resulted in the in-situ formation of relevant cocoa aroma compounds. After comparison with data obtained by headspace solid phase micro extraction (HS-SPME-GC–MS) on conventional roasted cocoa beans, ILR-CIS-GC–MS data on unroasted cocoa beans showed similar formation trends of important cocoa aroma markers as a function of fermentation quality. The latter approach only requires small aliquots of unroasted cocoa beans, can be automatated, requires no sample preparation, needs relatively short analytical times (<1 h) and is highly reproducible.