At first, I thought food preservation would be difficult to explain in a fantasy world.  My mind got stuck on refrigeration and pasteurization, which are more modern.  Yet, humans have been preventing food from going back since 12,000 BC.  So, it wouldn’t be surprising for a fantasy world to do this without magic.  For anyone who wants to make it more detailed, here are a bunch of methods we have in our world:

• Dehydration–  This is the first type of preservation found in human history and originated in the Middle East.  Meat was dehydrated to prolong it’s viability.  Later, people would perfect this on fruits.  At first, this was done using the sun, but fire would eventually be used instead.  This is also considered the earliest version of:
• Curing– This is done with meat to slow spoilage and sometimes make the food taste better.  Smoking is one version, which adds phenols to enhance the flavor.  Some believe this was stumbled onto accidentally throughout human history until it was figured out for good.  Salting is the other version and involves burying the meat in a container of salt.  Many germs that lead to food poisoning require moisture to survive, so this destroys them.
• Pickling– This is one of the forms of fermentation, which involves the food being put in a liquid where bacteria create lactic acid.  Various liquids can be used such as vinegar, salt water, and wine.  Unlike curing, this method is used on a variety of food types and not just meat.
• Sugaring– This is a weird one because some sites put it under fermentation and others under dehydration.  The method is that you put the food into a container of honey or a sugar-based liquid.  Microbes are drawn out by the sugar, which kills them.  This technique was more popular in regions where they didn’t have enough sun for dehydration or access to pickling liquids.  It is also what led to the creation of jams, jellies, and preserves.
• Cooling and Freezing– While there wasn’t refrigeration like we have today, ancient people did notice that food lasted longer when kept cold.  This will at least slow down the growth of harmful bacteria, but freezing could result in food lasting an entire winter.  Some methods were the creation of ice houses solely for food, burying meat in the nearby snow, and keeping caught fish within running, cold water.
• Boiling– This is self-explanatory and used primarily for liquids, but also the solid food put in them.  For example, a stew that is heated long enough will kill off all the bacteria in the meat.  That’s pretty much it.  You boil the liquid until all of the bad stuff inside is dead, which is typically when it’s been bubbling for a while.
• Canning and Jarring–  This method is more technologically advanced than the previous ones, but it’s viable for a fantasy world.  You don’t need magic for a person to create a container with a solid seal.  The real trick might giving them a way to get all of the air out of the containers without magic, but you can research all of the ways we do it in our world.

I’m sure there are more methods of food preservation, which can help stop a person from asking why the heroes aren’t getting food poisoning.  Hope people enjoyed this quick list of the common ones.