Quote from Daniel Decatur Emmett, one of the greatest composers of minstrel songs, born in 1815....
"In the composition of a 'walk around'(by this I mean the style of music and the character of the words), I have always strictly confined myself to the habits and crude ideas of the slaves of the South. Their knowledge of the world at large was very limited, often not extending beyond the bounds of the next plantation; they could sing of nothing but everyday life or occurrences, and the scenes by which they were surrounded. This being the undeniable fact, to be true to the negro peculiarities of song, I have written in accordance."
Minstrelsy was very popular on both sides of the Atlantic in the early 18th century. Eventually even black musicians were performing "minstrel" acts, going so far as to apply burnt cork to blacken their faces if they weren't black enough! Although it assumed the prejudices & stereotypes of the time, I think it does a disservice to both the black & white musicians involved to say it was simply a mockery of the slave songs. If imitation is the sincerest form of flattery, then talented white performers were certainly scouring the plantations for what they thought were the "hottest" musical ideas of the times, and if the slave songs of the time weren't good, who'd a been listenin'?
Most of the minstrel songs I've come across (and this includes Stephen Foster's material) deal with slave emotions of a sentimental and tender order. I think, as perverse as it may seem to modern sensibilities, that blackface minstrelsy was a powerful force in the softening of white public opinion toward the Negroes. How can you deny the humanity of a people when you're laughing at the foibles of their love affairs and filial relations?
Some names to look for in your research...
Dan Emmett, Charles Matthews, George Washington Dixon, Thomas Dartmouth (Daddy Rice) Rice, Joel Walker Sweeney and E.P Christy (the "old" Christy minstrels).
Frank in the dark, dark swamps.