(Fruitionsciences) - The exposure of vineyards and grapes to smoke can result in wines with undesirable sensory characteristics, such as smoky, burnt, bacon, medicinal or ash, usually described as ‘smoke tainted’.

The compounds in smoke primarily responsible for the taint are the free volatile phenols (e.g. guaiacol, 4-methylguaiacol, o-cresol, p-cresol, m-cresol, etc). These compounds are produced and released into the atmosphere when lignin in wood is burnt. The primary mode of entry for smoke-related volatile phenols into the vine, and accumulation in the fruit, is directly via the waxy cuticle on berries. When free volatile phenols enter grape berries, they can react rapidly with grape sugars to give the glycoside ‘bound’ forms of the phenols.