Properties and application of pectinase obtained from Galactomyces candidum using pectin extracted from mango peels as a carbon source

Abstract

Enzyme instability, poor levels of activity, low substrate specificity, and cost, limit the use of pectinase in the juice industry as well as in galacturonic acid production. Therefore, this research explored the properties of low-cost Galactomyces candidum pectinase with high heat and pH stability capable of degrading mango pectin. Pectinase was produced from Galactomyces candidum on the second day in a submerged fermentation broth supplemented with beef-extract, yeast-extract, and mango pectin at a pH of 5.0. The crude enzyme had a specific activity of 31.34 U/mg. After gel filtration, the specific activity and molecular weight of the enzyme were 39.96U/mg and 26 kDa, respectively. The enzyme's optimal pH and temperature were 5.5 and 50 °C, respectively. The maximum velocity (Vmax) and Michaelis constant (KM) of the enzyme were 73.53 μmol/min and 1.49 mg/ml. The activation effect of some metal ions on the enzyme was in the following order Mn2+˃Ca2+˃K+˃Fe2+> Co2+> Na+˃Zn2+> Mg2+˃Cu2+. Galactomyces candidum pectinase retained more than 70% of its original activity after incubation for 120 min at all the pH tested. Also, over 80% of the enzyme's original activity was retained after incubation for 120 min at 50 and 60 °C, while at 70 °C, 50% of its initial activity was retained. In addition, over 70% of the enzyme's initial activity was lost at 80 °C after incubation for 120 min. Spectral studies on the clarification of mango fruit juice showed that both crude and purified Galactomyces candidum pectinase were able to clarify mango juice, suggesting the enzyme's potential in the beverage industry.