Comparison of integrated large scale and laboratory scale membrane processes for the production of black currant juice concentrate

The aim of this study was to produce highly concentrated black currant juice by using multi-step membrane process. First the experiments were performed in laboratory scale to determine the operation parameters. The large scale measurements were carried out on the basis of the laboratory results. Microfiltration (MF) was used to clarify the raw juice. The clear juice was pre-concentrated by using reverse osmosis (RO). The final concentration step was performed by using osmotic distillation (OD). By the end of the three step process the initial 15–18°Brix total soluble solid content (TSS) of the juice was increased up to 63–72°Brix. The result of the laboratory and large scale experiments were compared to determine the scale-up aspects. To evaluate the raw, the RO-treated, the OD-treated and a commercial juice, sensory profile analysis was applied. Seven properties of the juice samples were investigated: colour intensity, transparent ability, odour intensity, sweet flavour intensity, acidic flavour intensity, black currant flavour intensity and general impression. Beside that the anthocyanin content (AC) was measured. The results of the analysis showed, that the concentrated juice is a tasty drink and its anthocyanin content is more than three times higher than the AC of the raw juice.