Vanilla essence occurs in two forms. Real seedpod extract is a complex mixture of several hundred different compounds, including vanillin, acetaldehyde, acetic acid, furfural, hexanoic acid, 4-hydroxybenzaldehyde, eugenol, methyl cinnamate, and isobutyric acid. Synthetic essence consists of a solution of synthetic vanillin in ethanol. The chemical compound vanillin (4-hydroxy-3-methoxybenzaldehyde) is a major contributor to the characteristic flavor and aroma of real vanilla and is the main flavor component of cured vanilla beans. Vanillin was first isolated from vanilla pods by Gobley in 1858. By 1874, it had been obtained from glycosides of pine tree sap, temporarily causing a depression in the natural vanilla industry. Vanillin can be easily synthesized from various raw materials, but the majority of food-grade (> 99% pure) vanillin is made from guaiacol.