Making Walnut Oil

I spend several hours daily now picking walnuts and laying them out in a designated room to dry. Some days “just” one bucket, other days more. And since we did not eat all walnuts from last year yet, I have been thinking about how to process them in a useful way. And I have decided to try to make walnut oil. I have wasted two kg of low-grade walnuts and one kilo of moderately good ones trying to devise a process that works and I did come up with one in the end.

The first try cost me three hours of work, 700 ml of acetone, and resulted in barely 50 ml of oil from 1 kg of shelled walnuts. Not good.

The second try cost me five hours of work, 1400 ml of acetone, and resulted in roughly 150 ml of oil from 1 kg of shelled walnuts. Better, but still not good at all. This second try also resulted in me having a still now. I might make separate posts about that after I test its newest iteration – the first iteration was not very good at recovering the acetone from the solution (acetone is just too volatile) and after I modified it, I found out I don’t necessarily need it anymore.

Because the third try resulted in roughly 500 ml of oil from 1300 g of shelled walnuts after three hours of work and without the use of any chemicals and with minimum use of elektrimcity. And with walnut oil costing around 40€ per liter, that is financially viable since the next batch should be finished faster – I have a functioning process now and there won’t be any fumbling next time.

So, here goes the process:

  1. Drying the shelled walnuts at 45 °C in a fruit dehumidifier for 12 hours. This step is necessary now because the walnuts are freshly collected from the garden and when ground, they do not release oil but make a paste from which the oil is very difficult to extract. My first attempts at drying the nuts for a shorter time (2 h at 80°C or roasting 5 min at 190°C) did not work, thus me trying to extract the oil with acetone. I learned that the important thing is to get the walnuts completely dry, the shelled kernels should rustle when agitated.
  2. Running the dried walnuts through a meat grinder. This picture is from my first attempt but it is representative of how the shredded nuts looked after first grinding in my final attempt too. I am using an old hand-cranked meat grinder because I did not want to use my mom’s kitchen robot for experimentation. I probably won’t use it for this anyway, grinding the nuts is a bit harder than grinding meat and I fear the robot could get damaged. This old thing was made in times when tools were made to last and not break a month after the warranty expires.

    © Charly, all rights reserved. Click for full size.

  3. Running the dried walnuts through the meat grinder again. This time they started to expel some oil already.

    © Charly, all rights reserved. Click for full size.

  4. And finally, I run the thoroughly shredded kernels through another nearly antique kitchen appliance – a hand-cranked juicer. This resulted in 550 g of highly compressed dry matter with some oil residue, and the rest was oil mixed with some fine particles.

    © Charly, all rights reserved. Click for full size.

  5.  Leaving the oil to settle out the particles. It will probably take a few days. I will skim the oil from the top in the meantime and add water for the particulate matter to drop into. I may use the still again to refine the oil further, using some chemicals again, but it can wait for later. For now, I just wait for it to settle. Here you can see how it settled after 24 hours.

    © Charly, all rights reserved. Click for full size

I was not particularly careful about Hi Jean this time. The first 1000 ml of walnut oil (including oil from the first three experimental runs) will be refined and boiled for use as a food-safe wood finish and not for direct consumption. I do not have personal experience with walnut oil yet but allegedly it has advantages over linseed oil. It has a lower viscosity and thus seeps easier into the wood. It dries quicker. And it does not yellow with age as much as linseed oil does so it should not discolor the wood as much as linseed oil does, making it useful for lighter woods as well as dark ones. I intend to make several end-grain cutting boards at some point in the future.

However, I have cleaned all the appliances thoroughly now and next time I am making the oil, I will also make 1 l of cold-pressed oil – or maybe even more – for consumption. Walnut oil is a bit of a luxury foodstuff so we have no experience with its culinary use either but I am sure we will find some use for it in our kitchen should we have it. And an advantage of 1 l of oil is that it takes a lot less storage space than 5 kg of unshelled walnuts or 3 kg of shelled ones. Making it does not cost nearly as much as even cheap cooking oils do in financial terms, picking and drying the walnuts has to be done anyway, so there is only some work on top of that. And whilst it is not easy or quick work, I do have more time than money and I need the exercise anyway.



  1. Tethys says


    I wonder if walnut oil contains the insect repellant and preservative compounds like walnut roots,bark, leaves and wood?

    Maybe a filtration step through cheesecloth or a paper coffee filter would render a non-cloudy end product without much added labor or expense?

  2. says

    @Tethys, I forgot to write that, but filtering is a definitive no-no. Trying to filter the debris with cheesecloth or a coffee filter was a huge mess and a complete waste. The fine particulate clogs up both the cloth and the paper in seconds completely tight and it does not filter out at all. The only result was oil-soaked rags/papers and a loss of material. It might work if I had rigged up vacuum-powered filtering, but definitively not under normal conditions. Even the fine sieve that I have added to the juicer clogged up pretty fast.
    @GAS, My labor ain’t worth spit. I don’t like that, but that’s the truth. And since a liter of walnut oil costs about 40,-€ and I could easily press 4-5 liters a day if I did nothing else, it is worth it. Not to mention that I enjoy doing these things and I take such work as a replacement for empty exercise at the gym.

  3. Tethys says

    Any labor that produces a valuable end product is worthwhile. Walnut oil is expensive because it is very labor intensive for less yield than other seeds that humans use to make oil. It takes many years for walnut trees to mature and bear nuts.

    Oddly enough, a television show (Chateau DIY)
    I watched last night mentioned that there is a Walnut Mill on the grounds of the featured Chateau in France, so clearly running them through a mill was a good first step. I am very jealous of that old food mill! I’ve been looking for something similar to process my yearly crop of cornelian cherries.

    A bit of research shows that pressing the mace is involved in the process, much like cheese gets pressed. If you could easily produce food grade quality, artisanal walnut oil, why wouldn’t you? It could be a highly profitable side business, and you already have the crop literally falling out of the trees. I’m sure an oil expeller and a press would be easy enough to procure, or rig up from things you have in the shop.

  4. moarscienceplz says

    “Walnut oil is a bit of a luxury foodstuff so we have no experience with its culinary use”.
    I make a red cabbage slaw with dried cranberries, pistachios, and walnut oil. WO is delicious, but very strong. I only use a couple of teaspoons in a recipe that uses half a large cabbage head. Also, it oxidizes and goes rancid very quickly. Do your best to keep it away from light, heat, and air.

  5. flex says

    Cool stuff. I’ve been thinking that for my black walnuts I might be able to build a husker similar to your nutcracker, but with a cavity to hold the unhusked walnut that has a husked-walnut size hole at the bottom and a plunger the size of the hole on the other arm. So when the arms are pressed together, the walnut is forced through the hole but the husk stays behind. Commenter rwiess @7 in the previous walnut thread got me thinking about that.

    I wonder if I crushed the shells and nuts at the same time would the nut pieces sink in water. That may be an easy way to separate them, leaving only small bits of nuts but since I’d be using them for baking that wouldn’t matter.

    Not that I’m likely to do that anytime soon anyway. I’ve got lots of other projects queued up, the first one is to build some more worktables so I have someplace to work on projects.

    But there is another point I’d like to discuss, or at least make aware. That’s the value of labor. I think that’s one of the most difficult concepts within economics; in a lot of ways it’s ill-defined. But at the same time it’s one of the core concepts.

    TL/DR version: The value of labor not in the market cannot be accurately measured with money. Also, pleasure cannot be measured using money.

    I actually agree with Marx that all value derives from labor. Even picking a pretty leaf from a tree, or a pretty shell from the seaside, requires labor. Not much, but some. The problem is in translating the value derived from labor into the tool we use to measure value, i.e. money. Typically this problem is solved using the market. The value of the labor is what someone else is willing to pay for it. There are certainly some problems with this solution, because typically the people who can afford to pay for labor need the labor less then those who need to exchange their labor for goods to survive. This imbalance is the basis for capitalism.

    However, there is a bigger problem in economic theory, Specifically, what is the value of labor if it isn’t placed on the market?

    Some economists suggest that labor should be a standard rate, say $15/hr. So that a person can calculate the value for any labor they do, and can determine if it would be cheaper to hire someone rather than do the work themselves. I think you can see the flaw in that already…. If the person making the calculation isn’t earning $15/hr during the time it takes to do the work, then the calculation doesn’t make sense. Since I don’t think this is very clear, let’s give an example… Let’s say I need to drywall a ceiling. If I do it it will take me about 12 hours of work, assuming my labor is worth $15/hr and we are not concerned with materials, that’s a cost to me of $180. Now I can hire someone to do it, and it will only take him 6 hours because he is highly skilled, but his labor rate is $25/hr. Yet, that means it will cost me $150 in labor. So that’s a clear savings of $30. Right? Not really. That only works if I am doing something else which earns me $180 in those 12 hours. If, during one of those 12 hours (which could be spaced days apart) I’m not earning $15, then the benefit to be to hire someone else drops. If I get $15/hr for only 11 of those hours, but I can’t sell my labor for $15 for that last hour, then my cost drops to $165. If no one is paying me for my labor, then those 12 hours of work I put in is a lot cheaper than the $150 I would pay to hire someone else.

    A closely related way to measure is the ‘opportunity cost’, which is a term of art which compares alternatives. There are a lot of situations where it makes sense to look at opportunity costs, but most of them are dealing with constrained resources. E.g. I have enough lumber to make three chairs or one table. I am definitely going to build either chairs or a table. If I sell what I produce, and the chairs sell for $20/each while the table sells for $50, I should build chairs because I will make $10 more in gross profit. But I can also say that because of the resource constraint I lost the $50 I would have made from building a table. I have two opportunities, one worth $50 and one worth $60, the opportunity cost is the value of what I didn’t choose. Much like the example above, the opportunity cost of labor is the cost of what could have been earned otherwise. But, as is pretty evident, if a resource is not constrained no opportunity need be lost. If Charly has the time and materials to make walnut oil, and that doesn’t interfere with other activities he wants to do, no opportunity is lost and no opportunity cost is incurred.

    Another tool economist’s often use is equivalent value. If, to use the above example, walnut oil sells for 40 Euros/liter, then if Charly makes 1 liter of walnut oil, he has created value of 40 Euros. Clearly there are problems with this method of calculating value too. Let’s assume that Charly doesn’t need to buy any equipment, but can use what he already has and only needs to purchase things which may be consumed in the process, things like the energy to dry the nuts, the cleaning supplies to sanitize the equipment, etc. Let’s say the combined cost of consumable materials is 2 Euros. But Charly can make 5 liters in 8 hours of work. Under the equivalent value idea, Charly’s labor is worth (40 -- 2) * 5/8 = 23.75 Euros/liter/hour for making walnut oil. But, at the same time the manufacturers of walnut oil to sell at groceries stores are probably not paying that much to make walnut oil. So, by that reasoning it is cheaper for Charly to buy rather than make.

    These different measures are useful, for their purposes. But they are really not well designed for trying to figure out the value of labor which is not on the market.

    I don’t know of a good measure which can be used to estimate the value of labor when it is not on the market. Even when labor is on the market, the amount of money it commands varies widely. Value itself is a very tricky subject. We use money to measure value, but at the same time none of us assign value equally.

    I’m not saying that what Tethys and Great American Satan are saying is wrong. It’s how we are taught to look at things. We measure value with money, and labor has value. But labor which is performed to create something for personal use, which is not going to be put on the market, is kind of a special case and it is really hard to assign an accurate value to it. Because there may also be value in the enjoyment of performing the labor, and you can’t measure enjoyment with money.

  6. says

    @flex, whoa, I did not expect a dissertation on the value of labor! Anyhoo, my labor ain’t worth shit. And I am exhausted all the time to do anything worthwhile. I have zero motivation to do anything, I have to convince myself to breathe.

    A thingamajig similar to the Nutkraken with a hole and a plunger should work for de-husking walnuts. We do have such a thingamajig, a small one, for removing cherry pits. And the same principle is used for removing olive stones as well so I see no reason why it should not work on walnuts,

    I am not entirely sure that water will help to remove meat from the shell, however. Both meat and the shell float in my experience. As I said, black walnuts are a definitive PITA. although the shells are very pretty and make wonderful ornaments.

  7. Jazzlet says

    Charly I am envious again :-)

    I mostly use walnut oil to flavour walnut bread, a couple of tablespoons to half a kilo of flour, more if I’m short on actual walnuts (I’d add 125g to that amount of flour). Walnut bread is excellent with cheese or preserved meats, it makes good toast which is superb with morello cherry jam or any preserve wmade from a sour fruit. I also use walnut oil in salad dressings, though sparingly as it is strong.

  8. flex says

    Heh, no one expects the wall-o-text.. I won’t apologize, because if I felt I needed to apologize I wouldn’t have written it in the first place. But I’ve been thinking about this for years. Labor is undervalued, and still haven’t found any economic theory which suggests a way to value it accurately. Few economic models even acknowledge the difficulty, and the few that do either gloss over it or say that eventually labor will not be valued because automation will do everything (driving the value of labor to zero). Saying the future will be roses doesn’t help the workers today. Your labor may not be marketable, but it has value.

    But that’s not what your post is about, and I shouldn’t drop another wall-o-text.

    As I think about it, if I didn’t care for the nut solids and just want the oil I could just dry the meat and shells at the same time and press them together. It would probably be a bit more labor, but it may be easier than trying to shell and separate the meat from the shells.

    But I’d like the save the meat for baking. I’ve got a recipe for black walnut cookies brought over from eastern Europe by my great-great-great-grandmother that I would like to to try. I’ve made it with store-bought black walnuts, but it would be nice to use the nuts from the trees around the house.

    I guess I’ll need to do it the hard way, when I get around to it.

    Which is why we love your posts, you seem to get around to doing the things we think we’d like to do ourselves. And you do a better job than we would, and are more creative in how you do them. I really look forward to reading your posts.

  9. says

    @flex, I do not think you could press the meal together with the shells. Black walnut has very hard and thick shells that tend to crack into big and sharp pieces, Those would completely clog up pretty much any crank-operated device pretty quickly.
    For best separating of meal from the shell, I recommend drying the de-husked walnuts for several days at least. Dried shells are less springy and easier to crack and dried meal shrinks inside the shell and is easier to tease out when the shell is cracked.

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