Brown butter is butter that has been heated until the water content has boiled off and the remaining liquid has turned brown. It is often called for in cooking and baking, for example in recipes for financiers.
Discussions of the process typically explain the brown color as browning of the milk solids in the butter due to the Maillard reaction. However, even when these milk solids are removed, as is done in most recipes by filtering or careful pouring, the brown color remains.
I believe I understand how the flavor components of the brown butter survive filtering - the volatile products of the Maillard reactions remain dissolved in the liquid fat - but is there a similar explanation for the brown color? Or is it down to the coarseness of the filters allowing small suspended particles through with the liquid?
Any details on the particular compounds responsible for the color, or the chemical processes involved in creating them, would be much appreciated.