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Why Are Walnuts Bitter ? Here’s How To Remove The Bitterness

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Walnuts are a common ingredient during the cold season, but especially in the fall months. Once the cold kicks in a little, your walnut tree is dropping fruit left and right. So naturally, you’re going to pick up all of those beauties and use them. Once you start cracking them, you realize a few of them are kind of bitter.

Why are walnuts bitter ? Is this something normal or are they going off ? Do walnuts even go bad ? Let’s take a look.

walnut bitter

Why are walnuts bitter ?

Walnuts are bitter because the brownish skins enveloping the nut itself are full of tannins, an antioxidant that is naturally bitter. Some walnuts have more tannins than others, and this is not a bad thing. The skins can be removed to tone down the bitterness.

Another reason walnuts may be bitter is when they get older and start to go off. A slight bitterness is normal, but overly bitter walnuts are definitely going bad and almost turning rancid. If you notice your walnuts are too bitter, it’s best to throw them out.

Keep in mind that walnuts may absorb scents from storage, so be careful to store them in something airtight, so they don’t pick up another taste.

How to remove walnut skins and the bitterness

Walnuts skins are fairly easy to remove, and the process through which this happens actually makes them delicious. Walnuts are great on their own, perfectly raw and fresh, but a little cooking helps them out.

You have two options when it comes to removing walnut skins: roast or blanch them. Do not try to do this with fresh, raw walnuts because the skins are stuck to the nut and won’t come off easily.

To blanch walnuts, bring a pot of water to a boil. Once it’s boiling, add in your cracked walnuts. Do so gently, so you don’t splash hot water all over yourself. Let the walnuts simmer for about a minute, then remove them from the water. Pop them in the oven to dry faster, or just allow them to cook until perfectly dry.

The skins should now come off easily, of the walnuts are completely dry. If they’re wet, the skins will stick to your fingers. 

Read also: How Long Do Walnuts Last ?

To roast walnuts, preheat your oven as high as it goes. Set your cracked walnuts on a baking tray, with baking paper on it. Make sure all the walnuts are in a single layer. Transfer the tray to the oven, and turn the heat down to low. 

Allow to sit for 5 minutes, then turn walnuts over, allow to sit for another 3 minutes. If you see the sides of the walnuts going dark brown to black, you’ve gone too far.

After the walnuts are done roasting, let them cool completely before touching them. Then, bring a clean paper towel and start rubbing the walnuts together in the towel. The skins should dislodge very easily, as the oil on the walnut will separate the skin from the nut. 

Whether you’re blanching or roasting walnuts, don’t expect 100% of the skins to come off. A small piece here and there may still be stuck to particularly deep nooks and crannies. Even so, the walnuts should taste much better.

Do walnuts go bad ?

Yes, walnuts can go bad, it takes about a year for that to happen. Walnuts need their shells intact in order to store well, and if you’ve shelled them you only have a few weeks to use them up. Oxidation leads to the natural oils in walnuts turning rancid, and this can happen if you keep the walnuts in sunlight, and in a warm environment. 

How to store walnuts

To store walnuts, you need a cool, dark, dry storage place and an airtight container, if the walnuts are shelled. If they still have their shell on, walnuts can easily be kept in brown paper bags, to keep a slight bit of airflow. 

walnut bags

What to do with leftover walnuts

Leftover walnuts are easily used in different types of desserts, though you can add them to savory meals as well.  Here are a few ideas on what to do with them:

  • add chopped walnuts to the Thanksgiving turkey stuffing
  • chopped walnuts in any pie or pastry with chocolate, vanilla, or caramel
  • ground walnuts in any cake batter, cookie dough, pie filling, cheesecake biscuit layer
  • use ground walnuts are a nice decoration for a more rustic-looking cake
  • ground walnuts are great to use as dirt or sand in an edible diorama
  • walnut milk is a real thing, just like almond milk

If you’re out of food to make, you can try a few ideas for shell-on walnuts. For example painting them silver or gold and using them as decorations for Christmas is a great way to make your holidays a bit more special. 

Or you can use whole walnuts and construct your own table candle holders, or even tealight holders in some really nice fall and winter themes. With a bit of fake snow and an evergreen twig or two, you can get some nice results.

In any case, walnuts are a treat and we recommend you use them up whenever you’ve got the chance.


So the bitterness comes from the skin, in order to remove it, you have to remove the skin. Check first to see if the walnuts are still good because if the bitter taste comes from the fact that they are bad, then you can’t save them.

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