What characteristic of buttercream makes it less stable in hot conditions?

The stability of buttercream in hot conditions largely depends on its fat content. Buttercream is essentially a mixture of fat, usually butter or shortening, and sugar, often combined with other flavorings or ingredients. The fat plays a crucial role in the structure and stability of the buttercream.

In hot temperatures, the butter (which is around 80% fat) can start to soften or melt, causing the buttercream to lose its shape and become overly soft or even runny. This instability is exacerbated in hot conditions, where the higher temperatures affect the physical properties of the fat, leading to a compromised texture and reduced ability to hold its form.

While sweetness, air incorporation, and texture do contribute to the overall characteristics of buttercream, it is primarily the fat content that dictates its performance, especially in challenging environmental conditions like heat.