One of the most common questions that we're are asked is "What is the shelf life of a #10 can once it is opened?"
With all kinds of food, the shelf-life will be decreased by three things:
1. How long it has been opened
2. How much it is exposed to oxygen and moisture
3. How much heat the food has been exposed to
The higher temperature that a food is stored at, the faster it looses nutrients and taste. Oxygen and moisture will also lower the shelf-life of a food item.
Try and store your food after opening in a cool, dark place and preferably in an airtight container. Usually, the plastic lid that comes with a #10 can will be sufficient.
Most people know that freeze-dried food has a 25 - 30 year shelf-life but does that change after it's opened? The quick and easy answer is yes, the shelf-life does change once you open the can.
The in-depth answer depends on how the freeze-dried food is prepared. The freeze-drying process slowly lowers the temperature and pressure in a chamber and removes the oxygen and water from the food. Once the oxygen and moisture are extracted, it allows the food to have an extended shelf-life free of spoilage. Add oxygen absorbers on top of that and you have a can of food with a long shelf-life of 25 - 30 years.
Once you open your can of freeze-dried food, it is automatically exposed to two things - oxygen and moisture in the air. That's why it's important to use the plastic lid and lock out the moisture as much as possible from an open can of food.
You'll be able to open the can and eat the contents for 6 to 12 months. When you open the can of freeze-dried food, you won't have to refrigerate it either. It won't spoil that quickly. However, if you do prepare a dish with water, you should treat that food like any other perishable item and refrigerate it.
If you're wondering if your freeze-dried food has gone bad look for signs of exposure. If the food is chewy and gummy, usually that's a sign of overexposure.
Dehydrated food is prepared in a similar way to freeze-dried. However, the moisture is taken out more quickly which doesn't allow for easy rehydration.
Dehydrated food, if stored correctly, can last for 3-12 months in an open can.
Items like dried grains, beans, rices, etc. will last for years in an open can. As long as you keep them covered and stored correctly, they won't spoil very fast.