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To evaluate the influence of carbohydrate addition on anthocyanin and soluble phenol stability, blueberry juices were added with 20% (wt/wt) of maltose, sorbitol and a mixture (1:1) of glucose and fructose. A juice without addition of carbohydrates was used as a control. The juices were frozen and stored up to six months at −10, −20 and −30 °C. The transition temperatures Tm′ correlated with those of the added sugars. The glass transition was shifted to higher temperatures by addition of maltose and no significant changes in the transition temperatures were noticed with storage time. Anthocyanin and soluble phenol changes were mainly influenced by storage temperature and storage time: the lower the temperature, the shorter the storage time, the lower the changes. Sugar addition had no influence on anthocyanin content. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]