I followed a red velvet cupcake recipe found online with lots of good reviews. I sifted the sugar because it was lumpy, then creamed butter and sugar as directed in the recipe. I used a stand mixer to prepare the batter, during and after finishing the batter, I used a spatula to clean the sides and bottom. However, when putting the batter in the cupcake liners, I noticed some white lumps. After baking, some of these white bubbles "surfaced and burst". I sampled one and found that it was crystallized sugar. Why would this happen if the sugar was sifted? It´s bothering me because I followed the recipe as written, measurements and preparation was done according to good baking practice. Argh!
Even if you cream the sugar and butter really well, if it is then not incorporated properly into rest of the batter when eggs, flour and liquid are added, they will rise to the top and burst. The only way to avoid it is to ensure you mix properly. In a stand mixer, sometimes stuff gets stuck right in the bottom of the bowl or on the beaters. You either have to mix that in, or avoid it completely when scooping out your batter.