Concentration and purification of lycopene from watermelon juice by integrated microfiltration-based processes

Abstract

The concentration of thermosensitive bioactive compounds remains an important challenge. A gentle integrated process including enzymatic maceration, crossflow microfiltration, diafiltration and centrifugation was applied to watermelon juice to obtain a natural extract enriched with lycopene. Microfiltration was performed using ceramic membranes with different pore diameters (0.2 to 1.4 μm), transmembrane pressures (50 to 200 kPa) and temperatures (50 °C and 60 °C). Using the best operating conditions during microfiltration, the permeate flux was close to 110 L·h− 1·m− 2, and the lycopene concentration increased 11-fold in the retentate. Diafiltration allowed for the purification of lycopene up to 25-fold. Centrifugation enhanced the lycopene concentration up to 4-fold. cis-Isomerization remained low and similar to that of raw juice. This integrated process obtained a natural extract of lycopene that was 41 times more concentrated and 34 times purer than the initial juice, yielding an extract with up to 2% all-trans-lycopene on a dry basis.