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.