pediaHazelnut oil, obtained from the fruit of the Corylus avellana L. plant (Betulaceae family) — hazelnut — by cold pressing, is a valuable plant oil. Turkey supplies approximately 70% of the world's hazelnut production, and the Black Sea Region is the heart of this production. Rich in oleic acid content, hazelnut oil is compared to olive oil and is widely used in cosmetic formulations as an emollient, moisturizer, and skin barrier support agent. This article addresses the botanical source of hazelnut oil, its chemical profile, its place in scientific literature, and its special role in soap making based on academic sources.
This article is not a product promotion. The aim is to present an independent framework regarding hazelnut oil's position in scientific literature. The information in this article does not contain any treatment claims.
Botanical source and Turkey's hazelnut heritage
Corylus avellana L., belonging to the Betulaceae (birch) family, is a deciduous shrub or small tree native to the temperate regions of Europe and Western Asia. It has been cultivated for thousands of years in the eastern Black Sea coast region of Turkey — particularly in Giresun, Ordu, Trabzon, and Rize provinces.
Turkey alone supplies approximately 65-70% of world hazelnut production, making hazelnut one of the country's most important agricultural export products. Hazelnut oil is the reflection of this rich agricultural resource in the cosmetic and soap-making fields. Hazelnut oil, traditionally used for culinary purposes in the Black Sea, has recently attracted attention in skin care and soap formulations.
Chemical profile: The Black Sea's answer to the Mediterranean's olive oil
Fatty acid composition
Hazelnut oil shows a strong similarity to olive oil in terms of fatty acid profile. Main composition: oleic acid (omega-9) 70-83%, linoleic acid (omega-6) 7-14%, palmitic acid 4-7%, and stearic acid 1-4%. This high oleic acid content increases the oxidative stability of hazelnut oil and strengthens its skin compatibility — oleic acid is also an important component of human sebum.
Natural antioxidants
Hazelnut oil naturally contains tocopherols (especially α-tocopherol / vitamin E), phytosterols, and squalene. Vitamin E content supports its oxidative stability while carrying antioxidant effect potential on the skin. Squalene, which constitutes approximately 12% of human sebum, is one of the factors enhancing the skin compatibility of hazelnut oil.
Physical properties
Hazelnut oil is liquid at room temperature, light yellow in color, and has a mild hazelnut aroma. Due to its light texture (low viscosity), it absorbs quickly and penetrates the skin without leaving an oily residue — this property is one of the reasons it is preferred especially in facial care products.
Place in scientific literature
Emollient and skin barrier research
The high oleic acid content of hazelnut oil is being researched for its potential to support the skin's natural lipid barrier. Oleic acid is an important component of the stratum corneum's (the outermost layer of the skin barrier) lipid matrix. In in vivo studies, it has been observed that plant oils rich in oleic acid reduce transepidermal water loss (TEWL) and increase skin hydration levels.
Antioxidant profile
The tocopherol and phytosterol content in hazelnut oil is being researched for its antioxidant capacity. In studies conducted by Amaral and colleagues (2006), it was reported that the fatty acid profiles and tocopherol contents of different hazelnut varieties vary depending on the variety. Turkish hazelnut varieties were found to be rich in α-tocopherol.
Cosmetic use safety
CIR (Cosmetic Ingredient Review) reports that Corylus Avellana Seed Oil is used in cosmetic products in various functions: skin conditioning agent (emollient), hair conditioning agent, and fragrance component. Hazelnut oil is generally considered safe with low irritation and allergy potential. However, individuals with hazelnut allergy are advised to be cautious — in persons allergic to hazelnut protein, topical hazelnut oil use can rarely trigger a reaction.
Hazelnut allergy note
Hazelnut is a tree nut classified among food allergens. Cold-pressed hazelnut oil may have higher protein content compared to refined oil. Individuals with a history of hazelnut allergy should consult a healthcare professional before using any hazelnut oil-containing product.
Safety profile
General safety
CIR (Cosmetic Ingredient Review) reports that Corylus Avellana Seed Oil is safely used as a skin conditioning agent in cosmetic products. It is generally considered safe with low irritation potential. In EU Cosmetics Regulation, hazelnut oil use is permitted under general provisions.
Hazelnut allergy: critical warning
Hazelnut is an important tree nut classified among food allergens and is covered by mandatory allergen labeling in EU regulations (EU 1169/2011). The protein content of cold-pressed hazelnut oil may be higher compared to refined oil — these proteins can trigger allergic reactions. Individuals with a history of hazelnut allergy should absolutely consult a dermatologist or allergist before using any cosmetic product containing hazelnut oil. Although the saponification reaction largely changes the structure of the oil, protein residue risk cannot be completely ruled out.
Hazelnut oil in soap making
Saponification value and recipe design
The saponification value (SAP — NaOH) of hazelnut oil is approximately 0.136 — very close to olive oil (0.134). This similarity allows hazelnut oil to be used as a partial or complete substitute for olive oil in recipes. With a medium-high iodine value (approximately 83-90), using 100% hazelnut oil in the recipe causes the soap to remain soft.
Usage rate
In soap recipes, hazelnut oil is typically used at a rate of 10-40%. In the olive oil-based Castile soap approach, "Black Sea Castile" style soaps can be produced by substituting hazelnut oil for olive oil. Application as a superfat at a rate of 5-8% after trace is also a common practice.
Properties it adds to soap
Hazelnut oil imparts the following properties to soap:
- Moisturizing feel: High oleic acid content leaves a soft and moisturizing feel on the skin after soap use.
- Creamy lather: Like olive oil, it creates a small, dense, and creamy lather structure — those expecting large and airy lather should balance it with coconut oil.
- Light texture: Does not leave a heavy or oily feel on the skin after soap use.
- Longevity support: The oxidative stability of oleic acid supports the shelf life of the soap (DOS risk is low).
Black Sea soap-making tradition
In Eastern Black Sea, hazelnut oil holds an important place in traditional soap making. Hazelnut oil-based soaps in local production in Rize, Trabzon, and Giresun form a special category — these soaps represent a tradition that carries the agricultural identity of the region into a cosmetic product.
Frequently asked questions
What is hazelnut oil?
Hazelnut oil is a plant oil obtained by cold pressing from the fruit of the Corylus avellana plant. It contains 70-83% oleic acid and its fatty acid profile is very similar to olive oil.
What does hazelnut oil do for the skin?
With its emollient property, it supports the skin's moisture balance. Thanks to its light texture, it absorbs quickly and does not leave an oily residue. It contains natural vitamin E and squalene, carrying antioxidant potential.
What does hazelnut oil do in soap?
It adds a moisturizing feel, creamy lather structure, and light texture to soap. Because its SAP value is very close to olive oil, it can be used as a substitute for olive oil in recipes.
Can people with hazelnut allergy use hazelnut oil soap?
Individuals with a history of hazelnut allergy should consult a healthcare professional before using any product containing hazelnut oil. Although the saponification reaction greatly changes the structure of the oil, protein residue risk cannot be completely ruled out.
What is the difference between hazelnut oil and olive oil?
Both oils are rich in oleic acid and have similar saponification values. Hazelnut oil has a lighter texture and absorbs more quickly; olive oil has a heavier body and more pronounced aroma. In soap making, they can be used as substitutes for each other.
Chailea products containing this ingredient
Hazelnut oil (Corylus Avellana Seed Oil) is used as a base oil in 22 Chailea products. View all products →
References
1. Amaral, J. S., et al. (2006). Hazelnut (Corylus avellana L.) Kernels as a Source of Antioxidants and Their Potential in Relation to Other Nuts. Journal of Agricultural and Food Chemistry, 54(12), 4833-4840.
2. Lin, T.-K., Zhong, L., & Santiago, J. L. (2018). Anti-Inflammatory and Skin Barrier Repair Effects of Topical Application of Some Plant Oils. International Journal of Molecular Sciences, 19(1), 70. doi:10.3390/ijms19010070
3. Parcerisa, J., et al. (2000). Fatty acids, tocopherols and sterols in hazelnut oil. Food Chemistry, 71(1), 113-120.
4. CIR Expert Panel. Cosmetic Ingredient Review — Corylus Avellana Seed Oil assessment data.