Where does “blanch” come from?

Blanch comes from Old French blanc, from Frankish blank, ultimately from Proto-Indo-European bʰel- meaning to shine or gleam.

blanch (English): To grow or become white; To take the color out...

Definitions

Step	Language	Word	Meaning
1	Old French	blanchir
2	Old French	blanc	white
3	Late Latin	blancus	white
4	Frankish	blank	bright; gleaming, white, blinding; bright,...
5	Proto-Germanic	*blank	—
6	Proto-Germanic	blankaz	bright, shining, white, gleaming, blinding
7	Proto-Indo-European	bhleg-	to shine, white; to shine, burn, scorch