Relationship between chocolate microstructure, oil migration, and fat bloom in filled chocolates

Abstract

Fat bloom is one of the main quality problems in the chocolate industry. A bloomed chocolate product is characterized by the loss of its initial gloss and the formation of a gray-whitish haze, which makes the product unappealing from a consumer point of view. In the industry, most of the fat bloom related problems arise in filled chocolate products, like pralines and chocolate-coated biscuits. In these products, oil migration is considered the main cause of fat bloom development. It leads to the dissolution of solid cocoa butter crystals in the chocolate shell which may recrystallize with the formation of undesired crystals. These give rise, upon growth, to visual fat bloom. When looking at the available literature, most of the studies elucidate the possible mechanisms of oil migration and the subsequent fat bloom formation using model systems. These model systems are sometimes too distant from the real industrial applications and the important role of the microstructure of the products are often neglected, although it plays a crucial role in migration-induced fat bloom development. The main objective of this review is to describe the relationships between chocolate microstructure, oil migration, and fat bloom. Practical applications: This review can be used as a base for the development of microstructural strategies to retard oil migration and fat bloom development in filled chocolates. An important strategy to retard oil migration and migration-induced fat bloom is the creation of more dense structures. By creating denser structures, the overall mobility is reduced leading to a decrease in the rate and extent of oil migration. Also, more dense structures hinder recrystallization and Ostwald ripening, thereby delaying the migration-induced fat bloom development. As fillings are less standardized and not bound by legislation, modification of the filling composition and microstructure offers more opportunities in delaying fat bloom. The main objective of the review is to describe the relationships between chocolate microstructure, oil migration, and fat bloom, as illustrated in this scheme. The numbers indicate the four parts that are discussed in this review

Ability of crystal promoters to delay fat bloom development in heat‐resistant compound chocolate with or without the presence of crystal inhibitor

“…In cocoa butter, the use of symmetrical disaturated TAGs, with a higher tendency to form the β V polymorph, is recommended and is associated with the anti‐bloom effect by avoiding the β V →β VI transition (Smith et al ., ). The nucleation agents with specific crystal habit may induce crystallization of fats in the desirable polymorphic forms (Delbaere et al ., ). By optimising the TAG composition to have the same polymorphic form as the desired polymorphic form, fat bloom can be inhibited.…”

“…This suggests that by adding STS bloom formation was retarded by twice the length it took for non‐addition of the crystal inhibitor. In chocolate, the similarity between the rigid structure of STS and cocoa butter TAGs triggers the co‐crystallization of STS with cocoa butter and constrains the crystal lattice in the β V polymorph, thus preventing the transition into the β VI polymorph (Delbaere et al ., ). In hydrogenated palm kernel oil‐based compound chocolates, Berger (), cited by Weyland & Hartel (), claimed that STS improved bloom stability by stabilizing the β’ form of the vegetable fat.…”

Effects of Fat Polymorphic Transformation and Nonfat Particle Size Distribution on the Surface Changes of Untempered Model Chocolate, Based on Solid Cocoa Mass

“…These are also similar to the peak positions reported for polymorphic form V in the above‐mentioned literature. From day 6, the peak intensity of form V became stronger and the characteristic peaks sharpened as an indication of postcrystallization processes such as “Ostwald ripening” (growth of large crystals at the expense of smaller crystals) (Delbaere, Van de Walle, Depypere, Gellynck, & Dewettinck, ).…”

Deliciosos Polimorfos

“…Existe una amplia comunidad científica internacional dedicada, en parte, a la búsqueda de una solución para evitar el fenómeno del Fat Bloom, el cual significa uno de los quebraderos de cabeza más tormentosos para los chocolateros. Todavía no se ha encontrado una solución evidente que pueda evitarlo completamente, aunque ya existen diseños de aditivos que permiten retardarlo (Delbaere et al, 2016). Lo que está claro es que la ejecución de un buen proceso de temperado del chocolate, que le otorgue una microestructura robusta y compacta y el cuidado de la temperatura de almacenamiento son aspectos cruciales para evitar la aparición de Fat Bloom.…”