Back in these days salt was a very important asset for preservation of food. In this game, especially if you have a city with "lake" tiles, you can grow a city very fast and get tons of food, but most of this food, fish, would go bad and spoil. The same with meats you get from butchers house. I think salt, and spices, can be used as goods to represent this. A building called the preservation hut or whatever the community decides is better will be introduced to the game. The professional "food preserver" will work this building. There will be a mallus in the form of reduced efficiency of food storage. This mallus does not apply towards food that is being eaten by citizens turn by turn. Perhaps -10% efficiency beginning and scaling up the greater the rate of food surplus. The idea is that food in We The People can grow colonists too fast in some ideal cases (multiple food resources) and it can be overpowering and much more efficient than getting colonists from crosses. In my capital I have 55 foods surplus a turn and the city is growing like a weed. Each citizen working at this building must use salt or spices, and while they work, they contribute towards reducing this mallus. A city that has many workers on this building will still grow fast. Combined with the health concept in this game I believe there will be a good balance between growth of cities by food surplus and the other sources of crosses and buying them from Europe. Thoughts?