Phenomenological model for predicting the “Conching Degree” of chocolate

In chocolate manufacturing, the conching process is one of the main stages during which rheological and sensorial characteristics of the chocolate are developed. Additionally, it is one of the most extensive stages, which reflects the high levels of energy consumption and limited capacities of the equipment used in production plants. To reduce operating time guaranteeing the desired chocolate quality, it is necessary to understand the phenomena that govern the dynamic behavior of the conching process. Thus, the aim of this work is to construct a phenomenological based semi-physical model to predict an indicator of the chocolate's sensory quality, namely “Conching Degree” (CD). The CD is calculated using the concentrations of two key volatile compounds: tetramethylpyrazine (TMP) and benzaldehyde (BA). Concentration profiles of TMP and BA, as well as moisture content (H%), are predicted by the model for the duration of the conching process of a semi-sweet chocolate. The chocolate quality is validated analyzing the chocolate's sensory profile. The obtained results allow to establish a model for predicting of the CD of the product with a value of 0.60 (mg∕kg)⁻¹ during 750 min of processing with an error rates of less than 10%. According to the sensory results, a greater CD improves the general quality and increases the chocolate notes in the product. Furthermore, we propose that reducing the conching time from 750 to 630 min does not significantly modify the sensory quality of the product, and results in the optimization of 100 h processing per month.