Final answer:
True, the softest margarines tend to be the most polyunsaturated, as polyunsaturated fats are liquid at room temperature and offer a softer texture compared to saturated fats, which are solid.
Step-by-step explanation:
In general, the statement that the softest margarines are the most polyunsaturated is true. Polyunsaturated fats contain more than one double bond in their fatty acid chains, which affects the physical properties of the fat, making it softer and often liquid at room temperature. This is in contrast to saturated fats, which tend to be harder and solid at room temperature due to their saturated fatty acid chains that pack tightly together with no double bonds. Margarines that are soft typically have higher proportions of polyunsaturated fats, which come from sources such as plant oils (e.g., soybean, corn), fish, flaxseed, and some nuts like walnuts and pecans.
Moreover, it's important to differentiate between unsaturated fats and trans fats. While they both may contain double bonds, the configuration and health implications are different. Trans fats, often found in processed foods and created through partial hydrogenation of unsaturated fats, are associated with negative health effects and are not the same as the naturally occurring unsaturated fats found in foods like vegetable oils and fish.