Lemon juice clarification using fungal pectinolytic enzymes coupled to membrane ultrafiltration

• Fungal pectinase was produced on orange peel.
• Effect of pectinase pretreatment conditions on the viscosity of lemon juice was investigated.
• Lemon juice treated enzymatically was less turbid and less viscous.
• The optimized treatment with pectinase was followed by UF.
• Clear and stable lemon juice was obtained.

Lemon juice was treated with Penicillium occitanis pectinase at various enzyme concentrations (0–1200 U/L), temperatures (25–50 °C) and times (0–90 min). The effect of these enzymatic treatments on the viscosity of the juice was evaluated. The optimum treatment conditions were: enzyme concentration 600 U/L, time 45 min and temperature 30 °C. Their application led to a 77% and 47% reduction of viscosity and turbidity, respectively. The enzymatic treatment was followed by ultrafiltration (cutoff value = 15 kDa). Analysis of the clarified juice indicated that enzyme depectinization permitted a higher permeate flux and a higher juice quality. The lemon juice obtained was clear, stable and characterized by viscosity = 0.7 mPa s, turbidity = 0.17 NTU, clarity (A650nm) = 0.063 and color (A420nm) = 0.232. Microbiological study showed that lemon juice was free from aerobes, molds, enterobacteriaceae and coliforms and was microbiologically stable during 3 months storage. Results suggested that enzymatic treatment coupled to ultrafiltration could be used for production of lemon juice with high commercial value.