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 o C, but only minute amounts occurred at 25 o C