Spoiling alert!

[Granger]

left out food turns stale and takes quality/fep hit

I vaguely remember people have asked for FEP-free food so they won't destroy their characters development opportunities when doing heavy labour, food spoiling through reducing the FEP would solve this (let it sit for a while until it is FEP and satiation free).

Regarding the mechanics: cellars and caves could slow the process, but no area should completely stop it. Food should be best fresh, drying meat on racks to keep it from spoiling (for a while) could be a thing though.

New Object: Ice Box (made from boards and insulation like straw)
Halts the spoilage while being stocked with ice (made from compacting snow) that slowly thaws away in it while preserving the contents. Similiar to compost bins and worms (no extra inventory for the ice needed) with thawing modeled through reducing the quality of the ice (reaching zero would thaw and vanish the item, giving an incentive to get good ice as it lasts longer), so you could decide on trading capacity (by adding more ice) to prolong the time till you have to come back and restock. Ice (as should snow) should melt somewhat quick outside Ice Boxes while in them only one piece would be consumed to protect the rest.

Some more options to obtain ice (or snow, as the ingredient) would be helpful to not shaft people outside the mountain range that much, possibly ice spires could be repurposed (giving ice for cooling instead of an overpowered curio booster) and be spread through L1 instead of the snow biome.

[tyrtix]

Some ways to preserve food in the past.

Smoked/salted/dried meats, also sausages and seasoning in general were a good way, especially for meat and fish.
Pickled/in oil preservation for eggs, mushrooms and a lot of vegetables.
Barrels of flour lasts for very long times (making baking products very good for use in long terms), apples and many fruits were both dried or preserved in barrels with hay or sand.
Cheese is a very long standing product, also oil preserved, and we already have olives, linen and pumpkins for oil production, by using a fruit press or mill.
The need for fresh or, better, preserved food makes more products available, more need for work and a LOT less ability to build a LOT of alts very easily, and more products available makes more tradable items.