The degree of saturation of fatty acids in a fat affects the temperature at which the fat melts. Generally, the more unsaturated the fatty acids, the more liquid the fat is at room temperature (at around 25 °C). In contrast, more the saturated the fatty acids, the firmer the fat. So, Sunflower oil is liquid at room temperature which means more unsaturation. The oils or fats which are semi-solid or solid are rich in saturated fatty acids e.g. Butter, Coconut Oil.
