Fat, moisture, and ethanol migration through chocolates and confectionary coatings

The migration of fat, moisture, and ethanol is a common problem with chocolate-coated confectionery products. Migration of one of these components into the coating leads to visual and sensory defects such as sugar or fat bloom, making the product unacceptable to the consumer. The migration rate depends on the structure and composition of the coating. The migration of each of these species can be slowed to a certain extent by proper tempering of the coating, because proper tempering will give a structure that resists migration. In the continuous lipid phase, these chemical species migrate mainly through the liquid portion. Thus, the migration rate depends on the amount of liquid oil present in the product. Migration can be delayed either by reducing the liquid fat content or by immobilizing the liquid phase. The actual mechanisms for the migration processes are speculative, and a more thorough understanding is necessary to better abate quality deterioration. Armed with this understanding, a manufacturer would know a priori the effect of changing the ingredient or process. A few methods for control have been suggested, but have found limited application. Mathematical models have been proposed to predict the migration behavior, but their application is hindered because of the simplified assumptions employed. There is a need for developing better models that combine mass transfer with the phase behavior to be able to accurately predict the migration process. This review discusses the current understanding of fat, moisture, and ethanol migration through chocolate coatings and also includes a brief description of the theoretical aspects governing migration.