How long will apricot kernels keep and why is this information important?
An apricot kernel's state of health plays a major role in its nutrient content. The length of time out of the shell and exposed to open oxygen will dictate how long they'll last once in your possession. Oxidation is not only the number one enemy to vitamins, it also causes nut and seed oils to go rancid at room temperature.
There are several factors that influence an apricot kernel's shelf-life. After apricot stones (whole seed, shell and all) have been removed from the fruit and allowed to dry naturally, they will keep for, at least, 3 years at ambient temperature (room temperature) if stored dry. The shell preserves the seed and protects it from environmental contaminants and oxidation. Once cracked and exposed to oxygen, the shelf-life begins, as does the process of rancidity. How the kernels are stored from this stage will dictate the shelf-life.
At refrigeration temperatures and stored sealed, either in an oxygen barrier bag or some other air-tight containment, the shelf-life will be approximately 2 years. However, how long ago the kernel was cracked must be taken into consideration. For this reason, a good rule of thumb is to halve the shelf-life, as it can seldom be known when the kernel was actually cracked from the shell. This is particularly true of imported nuts and seeds. Imported seeds are often well on their way to rancid, if not rancid already. A study conducted a few years ago (which I'm presently trying to find to reference directly) found that most imported nuts and seeds sold were, on average, at least, two years old before they made their way into the consumer's home.
When stored sealed and refrigerated, the process of rancidity is greatly slowed. At room temperature, an average shelf-life will be about 6 months to be safe. That said, nuts and seeds should always be stored refrigerated to prolong their life, their nutrient spectrum, and prevent them from going rancid. This will also prevent pest infestation, such as the dreaded pantry or meal moth.
Apricot kernels can be stored in the freezer, contrary to conflicting information elsewhere. Freezer storage has no impact on amygdalin levels; however, sub-zero temperatures will effectively kill living seeds, as the embryo can't survive prolonged periods of freezing. Once frozen, it's best to keep them frozen, as they are now dead and will enter a state of decomposition at warmer temperatures. They can be used straight from the freezer without concern of defrosting. Dried apricot kernels have very low moisture content, so they will never freeze solid and they will last indefinitely in this state. That said, my belief is that raw, living seeds are always best. Living seeds retain their full spectrum of nutrients, including those yet discovered.