Effect of fruit blanching on phenolics and radical scavenging activity of highbush blueberry juice

Frozen highbush blueberries (Vaccinium corymbosum L.) were processed into juice, and the influence was studied of a steam blanching step, applied to fruit before milling, on the recovery of anthocyanin pigments and total cinnamates, in relation to the radical-scavenging properties of blueberry juices. Inactivation of PPO induced a significant recovery increase of anthocyanin and cinnamate contents. Furthermore juice from blanched fruits was more blue and less red than that obtained in the traditional way, due to the positive effect of the thermal treatment on the extraction of the most soluble anthocyanin pigments, which are also the most intense blue. Blanching of fruit greatly increased the radical-scavenging activity of the juice, in relation to the higher recovery of anthocyanin pigments and total cinnamates. (C) 2003 Elsevier Ltd. All rights reserved.