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 manufacturing 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 (e.g.,
hexane), or
expeller pressing (i.e., squeezed directly from sunflower seeds by crushing them). "Cold-pressing" (or expeller 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 (resulting in a pale-yellow), 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 (and therefore well-suited to dishes that are raw, or cooked at low temperatures), but it will retain more of its original nutrient content, flavor, and color (light-amber). ==Uses==