New Textures of Chocolate Are Formed by Polymorphic Crystallization and Template Effects: Velvet Chocolate

Abstract

We report new types of chocolate textures with a soft mouth-feel (velvet effect) formed by controlling the crystallization and polymorphic transformation of cocoa butter (CB) with thermal treatment and template effects. A quick spray of molten chocolate liquor on chilled substrates (normally formed chocolate or metal) caused the crystallization of metastable forms of CB, which transformed to a stable form during subsequent heating processes. Cryo-scanning electron microscopy and confocal interferometric scanning microscopy were employed to observe the surface structures of the velvet chocolate. We characterized the domain sizes of the βV form for the CB crystals in velvet chocolate, which were much smaller and exhibited a lower melting temperature and softer mouth-feel than those in normally tempered chocolate. Polymorphic crystallization and transformation of CB were monitored in situ by X-ray diffraction by changing the temperatures of the substrates. It was obvious that the velvet effect was induced solely by decreasing the temperature of the substrates below 16 °C, because crystallization of the metastable γI form and subsequent transformation to βV of CB are prerequisites for forming velvet chocolate. The chocolate substrate was much more effective than the metal substrate in forming the velvet chocolate because of the template effect.