Identification and optimization of fungal pectinase isolated in screening stage for fruit juice industry

Pectinolytic enzymes or pectinases are a heterogeneous group of related enzymes that hydrolyze the pectic substances. The main industrial application of pectinases is the extraction and clarification of fruit and vegetable juices. The aim of this present study was identification and optimization of fungal pectinase isolated in screening stage for fruit juice industry.                                                                                                             

This study was performed on 50 samples of apple in decay, soil and juice concentrate factories wastewater that isolated from different provinces of Iran, periodic random. First, isolated fungi were investigated from enzyme activity by measuring the clear zone on pectin medium and enzyme production in submerged medium containing pulp and pectin apple as the sole carbon sources. The best strain was selected for enzyme activity. Then, were studied kinetic various factors of pectinase.

80 fungal were isolated from these sources that 13 of these fungi were positive pectinase activity with creation a clear zone around the colonies. The pectinase activity of the 13 (%16) isolates was assayed using apple pomace and pectin as the sole carbon sources in submerged culture fermentation. The most pectinase activity (0.4 U/ml) was related to the Aspergillus niger AN64 that was identified by morphological characterization. Giving the highest enzyme production rate in 72h. optimum temperate and PH for pectinase activity and stability were 30° C, pH 5. Temperature (20-50) and pH (3-7) ranges were obtained for pectinase stability. Ag1+ , Mg2+, Mn2+ and surface active detergents such as ammonium sulphate, yeast extract, EDTA and citric acid enhanced the pectinase activity.

This strain of A. niger AN64 can be used in fruit juice industry because tolerance in a wide range of the acidic pH and various temperatures.