Conventionally, berries are pressed by using pectinolytic enzymes which degrade the cell structure giving higher juice yields and elevated anthocyanin contents. Long self-life often applied for the commercial juice drinks is detrimental for the sensory and chemical properties of the juices. The storage conditions, such as temperature and light, determine the stability of easily degradable anthocyanin pigments. The stability of blackcurrant juices, processed with different technologies, was monitored in a 12-month storage trial, applying different conditions: room temperature in light, room temperature in dark and in refrigerator (+4 °C) in dark.

In our study, blackcurrants were pressed to juices using three different processes: 1) novel non-enzymatic berry pressing, 2) enzyme-aided pressing of the former press residue and 3) conventional industrial enzymatic pressing. Anthocyanins were analyzed by HPLC-DAD. The degradation of the colour was analyzed visually with trained sensory panel (n=11) using triangle test. The content of anthocyanins was 30 % higher in the enzymatically pressed juices than in the non-enzymatic juices. The content of anthocyanins in all juices dropped 70 % during 12 months of storage when stored in room temperature, but remained almost unchanged in the refrigerator. Surprisingly, no difference was found in the remaining anthocyanins when stored in light and dark at room temperature. When observed visually, degradation of the colour of the non-enzymatic juices was noticeably already after a month. Enzymatically pressed juices remained too dark for visual observation due to the high colour intensity. The study showed that the juice processing has an impact on the resulting colour intensity of the juices. Temperature has a more significant effect on degrading anthocyanins than light when stored in glass bottles. To retain the highest nutritional qualities of juices for commercial purposes, the self-life ought to be determined by taking into account the processing technologies and the storage conditions.