My family eats a lot of nuts in cereal, baked goods, and pasta sauces. This means that we always have a large stockpile of nuts at home. Unlike with our stockpile of salt, sugar, and flour, storing nuts so they don’t go bad is a bit tricky.
Below is what you need to know about the long-term storage of nuts, including shelf life, drying, and storage.
Do Nuts Go Bad?
Yes, all types of nuts can go bad. Exposure to air, high temperatures, and light will cause the nuts’ fats and nutrients to degrade. Moisture will speed up the degradation process and also allow mold and bacteria to grow.
The main reasons nuts go bad are:
- Rancidity: Nuts become rancid when their fats break down. Exposure to heat and air will make nuts go rancid very quickly.
- Pests: Pantry moths particularly love nuts. Some people have problems with rodents getting into their nuts storage as well. Read about how to prevent and get rid of pantry pests.
- Mold: Nuts are prone to molds, which produce byproducts called aflatoxins. These compounds are carcinogenic and can cause liver damage. Breathing in aflatoxins can also irritate the lungs. High moisture is the leading cause of mold growth in nuts.
- Bacteria: In addition to mold, nuts can sometimes grow dangerous bacteria. Salmonella and listeria outbreaks have been linked to nuts.
- Absorbing odors: Nuts can sometimes absorb the smells of foods stored near them. While this doesn’t make them unsafe to eat, it does affect the taste. Never store nuts near chemicals or cleaning items. (1, 2)
Nut Shelf Life
Recommendations vary, but most sources say that nuts will last up to 3 months in the pantry, 1 year in the refrigerator, and 3 years in the freezer. However, the shelf life varies depending on the temperature, type of nut, and whether it is shelled, roasted, or whole pieces.
Of all the things that affect nut shelf life, the temperature has the most significant impact. Even a slight increase in temperature can drastically reduce shelf life. The table below contains shelf life data taken from various studies. Note that not all nuts were studied at all temperatures.
Shelf Life in Months Stored at Various Temperatures
|Cashews||12||No data||6||No data|
|Hazelnuts||24||12||No data||No data|
|Walnuts||12||No data||3||No data|
Nuts in Shell vs. Shelled:
It shouldn’t be surprising that shelled nuts last longer than unshelled nuts. The shell is what allows nuts to make it through the winter to sprout in the spring. If the shell is removed, oxygen and humidity will get to the nutmeat inside.
Nuts that are still in their shell will last approximately 20-50% longer than shelled nuts.
Roasted vs. Unroasted:
Like storing coffee, roasting breaks down the natural oils in the nuts and starts the rancidity process. So roasted nuts will not last as long as unroasted nuts. Some types of unroasted nuts will last 4 times longer than if they were roasted.
Whole Nuts vs. Pieces:
Whole nuts will last twice as long as pieces of nuts. This is because pieces of nuts have more surface area and thus are exposed to more air.
Which Nuts Last the Longest?
Some nuts are more fragile than others because of the types of fat they contain. For example, chestnuts can’t be stored more than a month or two, even in optimal conditions. If you want to keep nuts long-term, avoid stockpiling any which go bad quickly.
Storing Nuts Harvested from Trees
If you harvest nuts yourself, you’ll have to dry them before storing. Otherwise, the nuts will have too much moisture, and bacteria or mold could start growing.
After harvesting the nuts, immediately remove the hull so moisture from the hull doesn’t absorb into the shell. Then spread the nuts on a screen or tray somewhere with good air circulation. Make sure rain doesn’t get on them. Every few days, break open a nut. If the nutmeat is still rubbery, then it needs to dry more.
How to Store Nuts Long-Term
Nuts generally aren’t a good food for long-term storage. Even when stored in ideal conditions, they will still get rancid. It’s best not to keep nuts for more than 2 years. Only stockpile as many as you can rotate through in this timeframe.
If you do want to store nuts for 2 years (or longer), you’ll need to use one of these methods.
This is the easiest method of storing nuts long-term. The low temperature slows oxidation and mold growth. You should still put the nuts in an air-tight container or vacuum-sealed bag beforehand to protect against oxygen and moisture.
Root cellars are great for storing unshelled nuts for a year or longer. The cool temperature in the root cellar preserves the nuts.
One problem with storing nuts in a root cellar, though, is humidity. Most root cellars need to be around 80% humidity to keep vegetables fresh. By contrast, nuts need a humidity of 55-70%. This room humidity will keep the nutmeat at its ideal humidity of 4-8% (hazelnuts and macadamia nuts need higher humidity).
If you plan on storing a lot of nuts in your root cellar, consider creating a separate area with controls for lowering the humidity levels. Keep the nuts in well-ventilated rodent-proof bins.
Sealed Containers with Oxygen Absorbers
Oxygen absorbers are packets of iron that remove oxygen from the air. When you put the nuts in a sealed air-tight container, such as a Mylar bag, you create an oxygen-free storage environment.
The nuts will still eventually go bad, especially if stored in high temperatures, but they will last much longer than if stored without oxygen absorbers. It varies but expect most nuts to last approximately 2 years when stored this way at room temperature.
Store in Honey
If you only have a small number of nuts to store, you can put them in jars of honey. Because honey is a natural preservative and never goes bad, nuts can last 2+ years stored in honey — even at room temperature.
Also, see how to store honey long term.
Canning in Syrup
One other method of storing nuts long-term is to can them in sugar syrup. Sugar acts as a natural preservative. Canning also helps remove oxygen and creates an air-tight seal on the jar.
Read more about home canning here.