LAUSR

Abstract Cooling processes for confectionery products have been widely assessed in terms of energy efficiency and processing conditions. During cooling, chocolate undergoes a complex polymorphic phase transition and related volume reduction which enables detachment from mold wall surfaces. Up to this point no related inline/online measuring technique has been introduced to quantify relationships between transient viscosity/elasticity increase, crystallization/solidification, related product volume shrinkage, and mold wall detachment. Accordingly, this paper focuses on an approach to couple an ultrasound (US) propagation/attenuation measuring technique with oscillatory shear rheometry and measure the complex storage and loss moduli (G′, G″) during crystallization/solidification of cooled chocolate melts and additionally influenced by the degree of pre-crystallization of these melts, also denoted as tempering degree by the chocolate experts. A decrease in the degree of pre-crystallization showed a lower temperature of the crossover of G′ and G″ indicating a later formation of the solid crystal network. Such measurements were expanded to follow the solidification state into the mold wall detachment phase. There the damping reduction of the ultrasonic amplitude correlated with the observed detached area of the chocolate from the transparent mold wall. Further showing that an increase in the chocolate tempering degree lead to accelerated wall detachment.