Chocolate Bloom

Chocolate bloom is the situation whereby fat crystals that were formed initially upon cooling a piece of chocolate, melts, migrates to the surface of the chocolate, and recrystallizes into a more stable form. This gives rise to an unstable appearance that is characterized by a dull color and grayish spots on the chocolate.
Chocolate bloom can be prevented by tempering of the cocoa fat before chocolate manufacture, and by hydrogenation of the emulsifier (usually lecithin) to a more stable form before use in the manufacture of chocolate.
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