I'm always open to reading more on this topic, but what is it that you're trying to say? Europeans weren't largely white in the 1400's?
As far as I know Europeans invented the concept of race to begin with as part of distinguishing themselves.
Well two things really, firstly that 'European' is essentially a meaningless term until quite late and that without that you can't have a characteristically 'European' colonialism. The south of Spain, for example, looked very different from, say, the north of Italy.
Up until then most of the endeavours we'd recognise as being colonial in character were by white Europeans on white Europeans. Even then, most colonial endeavours in the middle ages involve a displacement of a local elite with a foreign elite who eventually (if not immediately) lost ties with what we would consider the 'core' and then assimilate in to the local culture in the 'periphery'.
I'm not aware of any racial justification for colonialism in the high middle ages (you might get it later, but I'm not that familiar with it). You'd be far more likely to put it in religious terms e.g. the Angevins attempted to justify the conquest of Ireland by arguing that the Irish were pagans who needed bringing in to the Christian flock. Although you can easily see how that can be transformed in to racial justification, even the crusades were preached on the basis of religion and not race (Joshua Prawer and Ronnie Ellenblum are probably the two biggest names in the crusades as proto-colonialism, but I have to admit there is a lot of more recent scholarship on this that I haven't caught up with) which could just as easily be diverted against the white Cathar heretics in the south of France during the Albigensian Crusade or Lithuanian pagans in the Baltic ones as it could against Muslims in the Holy Land.
There's indisputably colonialism going on in the middle ages, but it doesn't look like the sort of colonialism you're talking about or easily fit the models we see in the early modern period.