Fresh meat, fish and some vegetables are not really edible before it's cooked. So my idea is that every household should need a set of pots and pans, made by the smith.
While acquired they may also produce salt from sea water. Then use it on fish and meat to make it last longer. Which brings me to the idea that some foods degrade over time. Fruits and some veggies rot quickly, though a few of those might be dried during the hot days in summer. Root vegetables last, longer, and so on.
-preservation of different food groups