A bowl of golden squash soup swirled with dark green pumpkin seed oil beside a chicory salad with walnut halves, a small heap of roasted hazelnuts and a scatter of green pumpkin seeds on an oak table

Nut and seed oils: The Complete Guide

Published 30 Sep 20267 min read

The nut and seed oils in this guide are pressed from the kernel and bottled to taste of it. Their makers suggest walnut, hazelnut and pumpkin seed oils for dressings, drizzles, baking and finishing. Two of the three have a home region with written rules. Walnut oil from the Périgord is a French appellation, and pumpkin seed oil from Styria has been protected under EU rules since 1996. The hazelnut oil in this guide comes out of the French milling tradition: La Tourangelle, which dates itself to 1867 in the Loire Valley, now makes it in California. For a first dish, see the nut and seed oils recipe guide.

From kernel to press

Périgord walnut oil, Styrian pumpkin seed oil and La Tourangelle's roasted nut oils are all pressed mechanically, not extracted with solvents. The kernel is ground to a paste, the paste may be heated, and a press squeezes out the oil. The heating step decides the style, and the specification for the Périgord appellation puts it in numbers. Cold-extracted walnut oil, labeled "extraite à froid," comes from paste that stays at or below 45°C. Warm-extracted oil comes from paste heated directly to between 60 and 100°C, in a pan no hotter than 180°C before the paste goes in. Styrian pumpkin seed oil is roasted as part of its traditional method. In one study, researchers describe roasted pumpkin seed oil as pressed from paste heated to 100 to 120°C, and cold-pressed pumpkin seed oil as made at no more than 50°C.

Heat trades fresh flavors for toasted ones and darkens the oil. The Périgord specification sets the ceiling. As the paste gets hotter, the fruity walnut aromas fade in favor of roasted notes. Above 100°C those notes turn too strong, and then the oil tastes burnt.

Walnut oil and the Périgord

The specification for Huile de noix du Périgord was homologated in November 2018, and it sets out where the nuts grow and how the oil is made. Among its rules:

Only four varieties may be used, Franquette, Marbot, Corne and Grandjean, with at least 50 percent Franquette.
The nuts come from identified orchards and trees within a defined area that covers much of the Dordogne and Lot and parts of neighboring departments.
Nuts dried with warm air must be dried at no more than 30°C.
From March 1 after the harvest, nuts and kernels are stored at 2 to 8°C, and none may be used after October 31 of the year after harvest.
After pressing, the oil settles in the dark for at least five days if it will be filtered and at least two weeks if it will not.

The specification describes the two styles separately. Cold-extracted oil ranges from straw yellow with pale green highlights to golden yellow. Its texture tends to be fluid, and it tastes of dry walnut kernels, bread crumb and fresh walnut. Warm-extracted oil ranges from golden yellow to golden brown. Its texture tends to coat the palate, and it tastes of walnut, baked bread crust, light toast and biscuit.

Warm is the norm. Nine in ten processors heat the paste, and a third still use the traditional cast iron pan over a wood fire. The traditional mill grinds kernels under a millstone of granite, flint or sandstone. The specification repeats a saying of the trade: the oil maker makes their reputation at the heating.

Hazelnut oil

La Tourangelle makes its roasted hazelnut oil (shop La Tourangelle roasted hazelnut oil) in Woodland, California, "strictly following 150-year-old French traditional methods." The company says its roasted nut oils are hand-roasted in iron kettles, expeller-pressed and lightly filtered. The La Tourangelle producer guide tells the company's story.

Hazelnut fat is built differently from walnut fat. A 2023 study of Turkish hazelnut cultivars measured oleic acid, a monounsaturated fat, at 76.04 to 84.80 percent of the kernel's fatty acids, and linoleic acid at 8.47 to 12.79 percent. The international standard for olive oil sets oleic acid at 55 to 83 percent. In these studies, that puts hazelnut closest of the three to olive oil in oleic acid. La Tourangelle rates its roasted hazelnut oil for medium-high heat and suggests it for sautéing, baking and finishing. The Piedmont in autumn guide covers the nut itself and gianduja.

Pumpkin seed oil and Styria

Styrian pumpkin seed oil is pressed from a pumpkin grown for its seeds. According to Austria's agriculture ministry, Styrian farmers first found a soft-shelled mutant of the pumpkin, now Cucurbita pepo var. styriaca, in 1880 and took it into cultivation. Steirisches Kürbiskernöl has been a protected geographical indication since 1996. The oil may be pressed only in defined districts of Styria and southern Burgenland, and the seed may also be grown in parts of Lower Austria.

The ministry lists the steps. Right after harvest the seeds are dried to 6 to 8 percent moisture. They are then milled fine in stone or cutting mills and kneaded with water and salt into a paste. The paste is roasted with constant stirring, which separates the protein from the oil. It is then pressed mechanically, without chemical aids, and the fresh oil stands for at least seven days so the sediment can settle. A liter takes 2.5 to 3 kilograms of seed. The oil is deep green with reddish highlights, thick-bodied and intensely nutty. Each genuine bottle carries a band with an individual control number.

In a 2016 study of Croatian pumpkin seed oils from the Styrian variety, the seven samples of straight pumpkin seed oil (two cold-pressed, five from roasted paste) ran from 45.6 to 56.2 percent linoleic acid and 28.8 to 39.1 percent oleic acid.

The three side by side

The fat figures come from three studies: one of three Iranian walnut cultivars, one of Turkish hazelnut kernels and one of Croatian pumpkin seed oils.

	Walnut	Hazelnut	Pumpkin seed
Home tradition	Périgord, France	French milling, now also California	Styria, Austria
Written rules	Huile de noix du Périgord appellation, 2018	The maker's own method	Steirisches Kürbiskernöl, EU protected since 1996
Heat in the making	Paste at or below 45°C (cold) or 60 to 100°C (warm)	Nuts roasted in iron kettles	Salted paste roasted; 100 to 120°C in one study
Color	Straw yellow to golden brown	Dark, per the maker's description of its roasted oils	Deep green with red highlights
Dominant fats (single studies, see text)	Linoleic 50.15 to 51.36%; oleic 23.47 to 25.13%; linolenic 10.48 to 12.04% (Iranian cultivars)	Oleic 76.04 to 84.80%; linoleic 8.47 to 12.79% (Turkish kernels)	Linoleic 45.6 to 56.2%; oleic 28.8 to 39.1% (Croatian samples)
On La Tourangelle's refrigerate-after-opening list	Yes, for its roasted walnut oil	Yes	Yes, for its toasted pumpkin seed oil
Uses the sources suggest	Vinaigrettes, dressings, drizzles	Sautéing, baking, finishing	Soups, salads, main courses, desserts, cheese

The fat row is where the three differ most. Linoleic and linolenic acids are both polyunsaturated. In the walnut study they add up to 60.63 percent at the low end (50.15 plus 10.48) and 63.40 percent at the high end (51.36 plus 12.04). Hazelnut's linoleic acid tops out at 12.79 percent, so in these two studies walnut's linoleic and linolenic acids together come to roughly 4.7 to 7.5 times hazelnut's linoleic acid. In these studies, pumpkin seed oil's linoleic and linolenic acids together fall between walnut's and hazelnut's. Of the three studies, only the walnut study found a large share of linolenic acid, an omega-3 fat.

The yield figure gives a sense of what goes into a Styrian bottle: at 2.5 to 3 kilograms of seed per liter, a 250-milliliter bottle holds the oil of 625 to 750 grams of seed.

Storing them

La Tourangelle's FAQ recommends refrigerating its roasted almond, hazelnut, pistachio and walnut oils, and its toasted pumpkin seed oil, after opening. By contrast, it tells customers to keep its olive, avocado, grapeseed and canola oils in a cool, dry place. The company gives unopened oils 18 or 24 months, depending on the type, and says most oils stay usable for about six months after opening. The regional rules point the same way. The Périgord specification requires the oil to be kept out of the light and at no more than 20°C until bottling, and the Austrian ministry's description calls for storing Styrian oil in the dark. The pantry storage guide covers the cupboard, and the nut storage answers guide covers the whole nuts.

How to use them

Where the makers point them. La Tourangelle suggests its roasted nut oils for stir-fries, marinades, vinaigrettes, drizzles, dressings and desserts. The Austrian ministry lists soups, salads, main courses and desserts for Styrian pumpkin seed oil. Olive oil has its own olive oil buying guide.

In dressings. The vinaigrette ratio guide gives the proportions for a dressing built on any of the three.

Pumpkin seed oil the Styrian way. The ministry singles out the oil's affinity for cheese and the way it clings to salad leaves. A thread over squash soup, as in the photograph above, puts the green color on show.

Tasting them. The method in the guide to tasting olive oil at home works for comparing the three side by side: a little in a small glass, warmed in the hand, smelled first and then tasted. For the whole nuts on the side, see the bar nuts guide.

For roasted nut oils, sesame oils and truffle-infused oils in one place, see Cooking Oils (Other Oils).