The Care and Storage of Walnuts

storing walnutsYesterday I talked a bit about my trip to see the harvesting of California walnuts in action. I love walnuts and eat them pretty much every day, partly because they are delicious and versatile, but also because they are rich in the plant-based omega-3 fatty acid alpha linolenic acid, or ALA (I wrote about this for The Seattle Times in July).

As with other omega-3s, ALA is extremely healthy, but it’s also a more fragile oil. In other words, it can go rancid easily if not stored properly. That’s why always store my walnuts in the freezer and my walnut oil in the fridge. When we were on the tour of the Barton Ranch and Gold River Orchards processing facility near Sacramento, they confirmed that walnuts have a shorter shelf life than other nuts in this respect, so when you buy them, treat them with respect by storing them right!

Another interesting factoid I picked up is that dark-colored walnut meat isn’t rancid, it’s just been exposed to more sun. Exhibit A (a little blurry…sorry!):


Walnuts at the top of the tree tend to get the most sun, especially the side that’s actually turned to the sun. This brings out more tannins in the walnut, which also increases the bitterness. That’s good or bad, depending on your point of view.

Some people don’t find the bitterness appealing, taste wise, but the bitterness means that the walnut has more antioxidants (walnuts contain a variety of antioxidants, more than most other nuts). This phenomenon is also true with many vegetables and fruits: As we’ve bred out the bitterness we’ve lost many nutrients (read Eating on the Wild Side by Jo Robinson if you want to know more about this). In this photo, the dark nuts have been sorted out:


So, if you like bitter greens, black coffee and dark chocolate (I’m raising my hand here), then embrace dark walnuts whenever you chance upon them. On the other hand, if you break open a walnut half and the flesh is gray inside, then it has gone rancid. (One of the dietitians on the trip made up a great rhyme: “If it’s white, take a bite. If it’s gray, stay away.”)

Now go put those walnuts in the freezer!

Disclosure: My travel expenses were paid for by California Walnuts, but my (many) thoughts, as always, are totally my own.