Fraunhofer Institute for Process Engineering and Packaging IVV, Giggenhauser Str. 35, 85354 Freising, Germany; Chair of Aroma and Smell Research, Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestr. 9, 91054 Erlangen, Germany.
Fraunhofer Institute for Process Engineering and Packaging IVV, Giggenhauser Str. 35, 85354 Freising, Germany.
Food Res Int. 2022 Dec;162(Pt B):112063. doi: 10.1016/j.foodres.2022.112063. Epub 2022 Oct 20.
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.
巧克力精炼是一个高度复杂的热机械过程，它改变了干起始材料的香气和流动性能。不同的巧克力精炼塑性体进行了特征描述。首次使用封闭腔流变仪（CCR）对塑性体进行了流变特性表征。从塑性体中提取的游离可可脂中，采用稳定同位素稀释分析（SIDA）和气相色谱-质谱法定量分析了乙酸、苯甲醛、（R，S）-（±）-芳樟醇、2,3,5,6-四甲基吡嗪和2-苯乙醇。在精炼过程中，游离可可脂的量可能由于解团聚而增加。塑性体的复合粘度随精炼时间的延长而降低。就香气精炼而言，所有五种香气活性挥发物的浓度随着精炼时间的延长而降低，尽管降低程度不同。乙酸的含量下降最明显，约为 60%，而芳樟醇的浓度下降最低，最多为 26%。总的来说，香气活性挥发物的极性或沸点越低，在精炼过程中浓度下降的幅度就越大。这些数据说明了精炼对质地和相应香气变化的影响，加深了对精炼对黑巧克力感官质量影响的理解。
