Effect of processing technologies and storage conditions on stability of black currant juices with special focus on phenolic compounds and sensory properties

- Comparison of juices produced with a two-phase process and a conventional pressing.
- Processing technology influenced stability of composition and sensory properties of juices.
- Non-enzyme-aided berry pressing produced juice with the lowest phenolic content and stability.
- Anthocyanins decreased and phenolic acids increased during storage of all juices.

Juice was pressed from black currants without enzyme treatment (NEB = Non-Enzymatic Berry) followed by re-pressing of the residue with enzymes (EPR = Enzymatic Press Residue) and the results were compared to the conventional enzyme-aided berry pressing (EB = Enzymatic Berry). EPR-juice had 9- and 5-fold higher contents of phenolic compounds compared with the NEB- and EB-juices, respectively. Effect of the low content and stability of phenolics was noticed as loss of the visual color in the NEB-juice during storage. The decrease in monomeric anthocyanins and the increase in phenolic acids were most severe in the NEB-juice, whereas the most significant decline in hydroxycinnamic acid derivatives occurred in the enzyme-treated juices. Storage in light induced less change in the phenolic composition in EPR-juice than in the two other juices. The study gave new knowledge on changes in individual metabolites, in sensory properties and in the shelf life of berry juices.