Pathways of 4-Vinylguaiacol Formation From Ferulic Acid in Model Solutions of Orange Juice

4-Vinylguaiacol (PVG), a major off-flavor in citrus products, was detected in stored model solutions of orange juice (MOJ) containing ferulic acid, and its amount increased with time and temperature. PVG was not found in MOJ incubated without ferulic acid. Vanillin, another ferulic acid degradation product, was also detected in MOJ containing ferulic acid after incubation at 35 and 45 °C, but only minute amounts occurred at 25 °C. Vanillin was not produced, however, in MOJ incubated with added PVG but which did not contain ferulic acid. Incubation of MOJ under nitrogen atmosphere rather than air or including butylated hydroxytoluene did not affect PVG levels even though nonenzymic browning products such as 5-(hydroxymethyl)furfural and furfural, and optical density values were reduced. Cu ions accelerated browning but decreased PVG levels. It appears that different factors affect PVG formation and sugar degradation.