I tend to disagree. Medieval antisemitism was mostly based upon religion, i.e. Jews as Christ-killers, murdering Christian children for their matzos etc.

Colonial racism and the idea of European exceptionalism of the 19th century grew out of Darwin's theory of evolution and Spencer's 'survival of the fittest'. In those days the general idea was that the white man was the top of humanity and that it should help develop the lesser man. This idea is mostly known as the White Man's Burden. (Also a poem from Rudyard Kipling).

Modern antisemitism comes from both those ideas. The original religious antisemitism got a boost from racial-scientific antisemitism. During these days people began to see Jews as a different race. Concurrently the seeds of Zionism start to spread in the late 19th century aswell.

Feel free to ask or contribute!