- great questions; been down that same road.... apparently the ends of the oats are 'clipped' off which then allows the hull to be rolled/beaten loose (inedible! - like vhewing a fingernail; they are Tough).... oat clippers are specialized units; the cheapest one found was 10k new (China).
.... oats may have been toasted to help remove the hull (destroys oil quality) - also there are 'hull-less' oat varieties (low yields).
.... 'brimstoned groats' (sulphured) were provided in lifeboats (even rats left them alone).
.... finally gave up and bought groats in 50 lb bags at the feed store; they also had whole, rolled, and steel cut for the same price ($18 per bag) - all were delicious (fed the whole oats to the chickens).
.... ended up bypassing oats in general; low nutrition like most grains - do enjoy them occasionally as oatmeal (steel cut - yum!).... mix in some d.e. to lengthen storage (bugs love them)
.... You are correct; the ancients Must have had a way to deal with the hulls..... :b