Assessing the Effects of Conching Parameters on the Physicochemical and Sensory Properties of Milk Chocolates

Despite the critical role of conching in the development of chocolate flow and sensory properties, objective knowledge about how individual operational parameters influence these outcomes remains limited. This gap constrains opportunities for manufacturers to increase productivity and lower energy consumption without impairing product quality. In this study, a fractional factorial design (FFD) was applied to systematically evaluate the main effects of conching parameters on the physicochemical, rheological and sensory properties of a model milk chocolate. The investigated independent variables were time (2 to 10 h), temperature (45 to 75°C), mixing speed (82 to 115 rpm) and fat content in the plastic mass (28% to 32 %) during the pasty conching stage, whereas a total of 52 response variables were assessed. Time and temperature significantly reduced Casson plastic viscosity and yield value, respectively, even though flow development was most efficient at the intermediate conditions of the investigated ranges (6 h, 60°C, 99 rpm and 30% fat). In contrast, higher fat contents in the plastic mass (32%) significantly increased flow parameters, likely due to reduced shear energy input, resulting in more viscous samples. These variations in rheology were reflected in the textural properties of the solid chocolates. The effects on most sensory attributes were relatively minor. Both time and temperature slightly increased the caramel flavour intensity, although higher temperatures contributed to the formation of particle clusters, potentially leading to a gritty mouthfeel. Despite the small sensory differences observed among samples, consumer acceptance remained consistently high across all trials, suggesting that any of the conditions within the tested ranges yielded high‐quality products. Rather than absolute optimisation, this study focussed on providing a systematic and comprehensive understanding of the main effects of processing variables on the quality of milk chocolates, a knowledge relevant to different industrial contexts and production scales.