[SuziQ]

My grandmother never used panko crumbs.

She probably made her own bread crumbs, which wouldn't have been as tiny and fine as the stuff you buy in the grocery store. The nice thing about panko is that it is rather coarse, so it doesn't absorb liquid, or likely, oil, the same way that regular bread crumbs do, so the coating stays nice and crunchy!

[Overtaxed]

She used plain all purpose flour.