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 lossâas can storage in bottles that are made of either darkly-colored glass, or, plastic that has been treated with an ultraviolet light protectant.