Concentration and selective retention of anthocyanins and proanthocyanidins from cranberry juice using pressure-driven filtration processes

The growing demand for functional foods has increased interest in concentrating bioactive compounds such as anthocyanins and proanthocyanidins (PACs) from various rich sources, with cranberry juice (CJ) standing out for its health-promoting potential. However, their efficacy may be hindered by their concentration highlighting the need for effective technologies to improve their efficiency and effects. In this context, pressure-driven membrane processes offer a promising solution. This study aimed to evaluate the concentration of these polyphenols using membrane filtration and to characterize the resulting fractions. Six membranes with different molecular weight cut-off (MWCO) from 150 Da to 5000 Da and two materials were tested at the same volume concentration factor to assess their efficiency in retaining PACs and anthocyanins. Results indicated that filtration preserved the physicochemical properties of the juice, showing only minor changes in conductivity (<1.15-fold increase) and °Brix (<1.5-fold increase) when using membranes with lower MWCO. Among these, the two lowest-MWCO membranes achieved the greatest retention of anthocyanins (up to 1.90 times) and PACs, with rejection coefficients of 90.2±0.5% and 93.7±1.4% for monomers, and complete rejection (100%) of 2–7 mers. This resulted in overall concentration increases of 1.72 and 1.65-fold in the retentates and provides scarcely documented, molecule-specific rejection coefficients for 16 molecules from cranberry juice across six membranes, demonstrating membrane filtration as an efficient strategy to produce cranberry juice enriched in bioactive compounds with potential health benefits. Process optimization is currently planned and the juices obtained will be tested on mice in a future study. • Nanofiltration concentrated cranberry anthocyanins up to 1.9-fold efficiently. • Rejection coefficients reached 100% for PACs and 90% for anthocyanins. • Rejection coefficients were calculated for 16 cranberry juice molecules. • Filtration preserves juice properties while enriching it in PACs and anthocyanins. • Six membranes tested; lowest MWCO showed highest retention of key polyphenols.