ROLE OF HYDROXYCINNAMIC ACIDS AND VINYLPHENOLS IN THE FLAVOR ALTERATION OF BLOOD ORANGE JUICES

Free and total ferulic and p-coumaric acids were determined in two pro cessed blood orange juices produced in Italy: one freshly squeezed and the other from concentrate. Hydroxycinnamic acids and their correspon ding decarboxylation products, p-vinylguaiacol and p-vinylphenol, were also determined in the juices for up to 4 months of storage at 4 and 25 degrees C. The flavor threshold of authentic vinylphenols in aqueou s solution and in the blood orange juice was evaluated by sensory anal ysis. Concentration of these off-flavors in the stored juices abundant ly exceeded the threshold values, especially in the juice from concent rate. The content of vinylphenols might provide a reliable index of bl ood orange juice quality.