Enrichment of lycopene in watermelon juice by ultrafiltration: technical assessment and fouling analysis

Abstract

SummaryWatermelon juice is proven to be a potential source of lycopene, but its exploitation and consumption are currently constrained. The research focused on lycopene enrichment in watermelon juice by ultrafiltration (UF) with 1000 Da of molecular weight cut‐off (MWCO). The selectivity of UF membrane for the constituents in watermelon juice was investigated from 2 to 8 bar by dead‐end mode combined with stirring. The 1000 Da UF membrane showed a high potential to recover and separate lycopene from other components. However, membrane deposition and capillary occlusion could occur, affecting the overall efficiency of the enrichment process. To better understand kinetics, phenomena and efficiency, the study was evaluated in cross‐flow mode with full recirculation of retentate. The enrichment efficiency was found to increase the concentration and purity of lycopene by several times. The concentration polarisation was used to describe permeate flux decline, while the Hermia model was developed to explain fouling mechanisms. The utilised models were highly compatible; additionally, pore blocking was thought to be the main mechanism of fouling in lycopene enrichment by 1000 Da UF. The built mathematical model was in good agreement with the experimental observations of permeate flux, and lycopene, TS and ash concentrations. The 1000 Da UF of watermelon juice is a feasible approach for lycopene enrichment.