Are you liking at the raisins for yeast nutrition? Better to look at actual nutrient protocols.
"For raisins to be a significant source of YAN for yeast fermentation, you'd literally have to add them to your mead by the POUND- and not by the handful."
I rinse my raisins (or other dried fruit, depending on recipe) in hot water twice to rinse off any residues and then snip soak them in almost boiling water to sanitize/rehydrate them. Then roughly chop them and the water in a sanitized blender.
I've never had any problems with infection or fermentation