Four types of sunflower oils with differing concentrations of fatty acids are produced through plant breeding and industrial processing: high-linoleic, high-oleic, mid-oleic, and high-stearic combined with high-oleic.
High-linoleic, 69% linoleic acid
High-oleic, 82% oleic acid
Mid-oleic, 65% oleic acid
High-stearic with high-oleic, 18% stearic acid and 72% oleic acid
In an analysis of the sunflower genome to reveal plant metabolism producing its oil, phytosterols were identified, as confirmed in another analysis of sunflower oil components, including polyphenols, squalene, and terpenoids.
Several varieties of sunflower oil seeds have been developed by standard plant breeding methods, mainly to vary the amounts of oleic acid and linoleic acid which, respectively, are the predominant monounsaturated and polyunsaturated fats in sunflower oil. Sunflower oil is a rich source of vitamin E.
Physical properties
Sunflower oil is liquid at room temperature. The refined oil is clear and slightly amber-colored with a slightly fatty odour.
Because sunflower oil is primarily composed of less-stable polyunsaturated and monounsaturated fatty acids, it can be particularly susceptible to degradation by heat, air, and light, which trigger and accelerate oxidation. Keeping sunflower oil at low temperatures during manufacture and storage can help minimize rancidity and nutrient loss—as can storage in bottles that are made of either darkly-colored glass, or, plastic that has been treated with an ultraviolet light protectant.
Methods of extraction
Sunflower oil can be extracted using chemical solvents, or expeller pressing. "Cold-pressing" sunflower seeds under low-temperature conditions is a method that does not use chemical solvents to derive sunflower seed oil.
Refined versus unrefined
Refining sunflower oil through solvent extraction, de-gumming, neutralization, and bleaching can make it more stable and suitable for high-temperature cooking, but doing so will also remove some of the oil's nutrients, flavor, color, free fatty acids, phospholipids, polyphenols, and phytosterols. Also, some of the polyunsaturated fatty acids will be converted into trans fat due to the high temperatures involved in the process. Unrefined sunflower oil is less heat-stable, but it will retain more of its original nutrient content, flavor, and color.
Refined sunflower oil is used for low-to-extremely-high-temperature cooking. As a frying oil, it behaves as a typical vegetable triglyceride. Unrefined sunflower oil is a traditional salad dressing in Eastern European cuisines. Sunflower oil is also an ingredient in sunflower butter. Methods for cooking snack foods, such as potato chips or French fries, may use sunflower oil.
Seed meal
Extraction of sunflower oil leaves behind the crushed seeds, typically referred to as seed meal, which is rich in protein and dietary fiber and used as an animal feed, fertilizer or fuel.
