Aroma-active volatiles and rheological characteristics of the plastic mass during conching of dark chocolate

Yvonne Guckenbiehl, Anna Martin, Eva Ortner, Isabell Rothkopf, Ute Schweiggert-Weisz, Andrea Buettner, Susanne Naumann-Gola

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Chocolate conching is a highly complex, thermomechanical process that transforms the aroma and flow properties of a dry starting material. Different conched plastic masses of dark chocolate were characterized. Rheological characterization of plastic masses was performed for the first time using a closed cavity rheometer (CCR). In free cocoa butter derived from the plastic masses, acetic acid, benzaldehyde, (R,S)-(±)-linalool, 2,3,5,6-tetramethylpyrazine, and 2-phenylethanol were quantified by stable isotope dilution analysis (SIDA) and gas chromatography-mass spectrometry. During the conching process, the amount of free cocoa butter increased possibly due to de-agglomeration. The complex viscosity of the plastic mass decreased as a function of conching time. Regarding aroma refinement, the concentrations of all five aroma-active volatiles decreased with increasing conching duration, albeit to varying degrees. The level of acetic acid showed the most pronounced decrease of about 60%, whereas linalool exhibited the lowest decrease in concentration, up to 26%. Overall, a lower polarity or boiling point of the aroma-active volatiles was linked to a stronger decrease in concentration during conching. These data illustrate the influence of conching on texture and the respective aroma changes, which deepens understanding of the conching effect on the sensory quality of dark chocolate.

Original languageEnglish
Article number112063
JournalFood Research International
StatePublished - Dec 2022
Externally publishedYes


  • Aroma concentration
  • Chocolate flavor
  • Chocolate texture
  • Closed cavity rheometer
  • Free cocoa butter
  • Plastic conching


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