Look at the product's ingredient list for a mention of real truffles, and watch out for any chemical ingredients. Avoid products that have labels such as “natural truffle aroma” or “truffle flavor.” The highest quality truffle oils have some truffle pieces at the bottom of the bottle and have a distinct truffle flavor. Sadly the majority of truffle oil isn’t actually made with truffles. The main ingredient is often a chemical designed in a laboratory to mimic the aroma of truffles (synthetic 2,4-dithiapentane). The result is an overly pungent oil that falls flat on any dish.