What causes the over-crystallization of chocolate?

The answer focuses on how allowing chocolate to drop below the acceptable working temperature leads to over-crystallization. Chocolate is a delicate mixture that requires careful temperature control to maintain its smooth, glossy texture and prevent unwanted crystallization. When chocolate cools too much, especially below the recommended working temperature, the cocoa butter within it can start to crystallize in an uncontrolled manner. This results in a grainy texture, dull appearance, and can affect the overall mouthfeel and quality of the final product.

Maintaining chocolate within an optimal temperature range is critical, as it allows for the proper formation of stable cocoa butter crystals, contributing to the desirable characteristics of tempered chocolate. The other options, while they involve aspects of chocolate handling that can affect its quality, do not directly address the specific issue of over-crystallization in the same way that falling below the acceptable temperature does.