Concentration of lycopene from watermelon juice using cross-flow filtration assisted with diafiltration

Abstract

Watermelon is a well-known and high-consumed fruit in Vietnam, considered a rich source of bioactive compounds, especially lycopene. The cross-flow filtration coupled with diafiltration was processed to obtain the concentrated lycopene. The microfiltration process was conducted at a temperature of 50-60oC by using a ceramic α-Al2O3 membrane with a pore size of 0.08 µm. Permeate was removed while the collected retentate was fractionated into two parts for further experiments. The first part of the retentate was directly centrifuged. The effect of centrifugation time (2, 5, and 8 mins) and speed (1000, 3000, and 5000 rpm) on lycopene content were evaluated. The other part of the retentate was purified by the diafiltration process. The ratio of retentate: water was varied from 1:0.5 to 1:2 (w/w) to determine its influence on the lycopene content. The results showed that the suitable transmembrane pressure was selected at 5 bars. The membrane fouling phenomena was also observed by a rapid decrease in permeate flux in 40 min, followed by a gradual reduction. The suitable condition of centrifugation was processed at 3000 rpm in 5 mins. The centrifuged retentate in 60 mins of microfiltration contained a lycopene content of 146.63±2.76 µg/mL. The retentate: water ratio of 1:0.5 was noted as an effective ratio to purify the lycopene content, achieving 273.42±4.56 µg/mL. The physicochemical properties of the raw watermelon juice and retentate indicated a positive result from the retentate with enhanced total solid content, lycopene concentration as well as purity.