Review Extraction Process, Properties, Characteristics, and Types of Carrier Oils

Carrier oils, also known as fatty-acid vegetable/base/fixed oil, are derivatives of seeds, nuts, or kernels of diverse plants. They are critical components in cosmetics and aromatherapy massage oils. Several carrier oils are available in the market, and they differ from each other in color, viscosity, penetration speed, and fatty acid profile besides rates. They affect the usefulness of the massage, color, scent, therapeutic properties, and lifespan of the final product. The selection of a carrier oil depends on the desired outcome.

Carrier oils provide the lubrication required for a massage and prevent the potential irritation, redness, sensitization, or burning caused by the undiluted use of pure essential oils, absolutes, and CO2 extractions.

Carrier oils have individual therapeutic properties and contain fat-soluble vitamins, minerals, antioxidants, and other nutrients. They can improve the look and feel of skin and hair by adding moisture and reducing the effects of dryness.

Extraction Processes of Carrier Oils

Cold press and expeller press are two main processes followed to extract carrier oils.

Cold Press - Cold pressing is a chemical-free process that involves placing high pressure on seeds, nuts, or seeds and squeezing out the oil. A filtration process takes place to get a finished oil. The cold-press process does not leave any solvent residue, so the resultant oil is cleaner, purer, and higher in natural colors and scents.

Expeller Press - It is a mechanical process using hydraulic pressure and heat. It is essentially a cold-press method at room or low temperatures. But when the temperature used rises above 120 degrees celsius, it is no longer a cold-press method. The manufacturers also abbreviate the term and use the RDB word for it. RDB means Refined, deodorized, and bleached. The refinement process removes impurities, improves the color and texture, or stabilizes the shelf life, making them suitable cosmetic uses.

Oil Maceration - It involves the use of botanicals holding meager oil to be obtained through a cold press. The maceration process retains the fragrances of botanical matter used in the carrier oil. In this process, botanicals are bruised and soaked in the carrier oil for a specified time. Sometimes, low heat is applied for easy infusion, and the infused liquid is filtered to obtain macerated oil with therapeutic properties of vegetable oil and the infused botanical material. Cosmetic manufacturers can use macerated oil as an ingredient for fragrance and moisture in skin care products.

Solvent extraction - It has three stages; soaking of botanical material, filtering of solvents, and extraction of oil. It employs solvents such as ethanol, petroleum ether, hexane, or methanol.

Cosmetic manufacturers prefer to use a natural, unadulterated, cold-press oil. They assess the aroma, extraction method, consistency, absorption rate, shelf-life, natural fatty acids, and tocopherols in a carrier oil. They also evaluate the following parameters in oil to check their suitability in the end product,

Parameters for Checking Oil Suitability

Moisture Content - The optimum proportion of moisture content of an oil indicates the storage stability of the oil. The moisture content of 10 to 12% is desired for storage stability.

Peroxide Value - The peroxide value gives an idea about the potential rancidity of the oil. The oils with lower peroxide values are desirable.

Saponification Value - Saponification value indicates the usage potential of essential oil in soap making, degreasing, and shampoo. It has an inverse relationship with the molecular weight of the oil. The higher saponification value of the oil shows a high potential for usage in the laundry industry for soap making, degreasing, and shampoo.

Iodine Value - It is a measure of the unsaturated acids, fats, and oil present in the carrier oil. It explains the liquid nature of the oil at room temperature. A higher iodine value indicates more possibility of oxidization. The carrier oils with lower iodine values are desirable in cosmetics and edibles to ensure low reactivity.

Acid Value - Acid value indicates the potential corrosiveness of the oil. It determines its use as biodiesel, paint oil, or edible oil. The carrier oils whose acid value is less than 10 are edible. Non-corrosive, edible carrier oils are useable as biodiesel or paint oil.

FFA (Free fatty acid) - It indicates the percentage of oleic acid of the carrier oil. The optimum proportion of oleic acid makes it a desirable ingredient in cosmetics. FFA of 1.30 ± 0.01% of bottle gourd oil is evidence of oleic acid, indicating that the oil is edible and can be applied for industrial purposes.

Other Considerations While Picking Carrier Oils

The manufacturers of toiletries and cosmetics also assess the nature of pure and natural carrier oils. They choose the appropriate types of carrier oils as per the product.


Types of Carrier Oils Available

Hard Oils - These carrier oils are solid at room temperatures and provide firmness to the end products such as soap while keeping a soap bar soft or sticky. Examples of hard oils are palm and coconut. The users need to melt them down for use.

Soft Oils - They are liquid at normal temperatures, and add nourishing and moisturizing properties to a finished product. Their presence in a soap bar reduces the brittleness of soap. The popular soft oils are olive, sweet almond, argan, rice bran, and canola.

The manufacturers substitute hard oils in place of hard oils, and the same for soft oils in a formulation. They evaluate each oil’s contribution in preparation in terms of firmness, moisture, or even lather. If they want to reduce the hardness or softness of the end product, they may increase the ratio of soft oils or hard oils.

Industrial users examine the source of oils and their characteristics to pick the right carrier oil for end products.

Characteristics of Nut Oils, Seed Oils, Fruit Kernel Oils, and Fatty Acid Oils

Nut Oils - They are excellent emollients that soothe sensitive, dry, sore, and inflamed skin. Nut oils include almond, hazelnut, macadamia, and walnut carrier oils. They are ideal ingredients for anti-aging and face masks.

Seed Oils - They rejuvenate skin complexion and repair damage caused by dryness. Seed oils include baobab, black currant, borage, broccoli, and carrot seed carrier oils.

Fruit Kernel Oils - They are lightweight and do not leave a greasy residue. Fruit kernel oils include apricot, avocado, grapeseed, peach kernel, and olive carrier oils that are gentle, cleansing, softening, and nourishing.

Essential Fatty Acid Oils - These oils are argan, babassu, and calendula. They hydrate the skin and possess outstanding anti-inflammatory, antibacterial, antifungal, astringent, and antiseptic properties.