Abstract:Pectin is widely found in plant cell wall and inner layer, which promotes the formation of plant morphology through cross-linking with cellulose and hemicellulose. Pectinase is a kind of enzyme that can degrade pectin. After being treated with pectinase, the cell contents of fruits pulp can be better released. Plantain is a kind of major tropical and subtropical fruit. However, about 30% of the annual world yield was lost due to the highly active internal plant cell wall macro molecules degrading enzymes of ripe plantain. Developing industrial-scale plantain juice can reduce the annual lost and bring additional value. Here, we found a commercial Aspergillus niger pectinase Pectinex XXL was most active at pH value 4.5 and was almost stable at pH 3-4.5. The optimal pH value and pH stability range of this enzyme were similar to the pH values of some tropical and subtropical fruits. In addition, the enzyme also exhibited a good thermal stability. The optimal temperature of Pectinex XXL was 60 oC, and after a 40 oC bath for 1 hour, the enzyme remained stable. Metal ions tolerance experiment found that the enzyme activity of Pectinex XXL was not inhibited by 1 mmol/L Na+, Mg2+, Ba2+, Co2+, Zn2+, Fe2+, slightly inhibited by 2 mmol/L K+ and Fe2+, and partially inhibited by 1 mmol/L and 2 mmol/L Ca2+ and Mn2+. After one-hour incubation, the enzyme (16 U/mL) significantly increased the yield and light transmittance of plantain / cherry tomato juice for 119.03% / 15.97% and 37.65% / 12.35%, respectively; and reduced the velocity of juice for 88.29% / 29.50%. In this study, the enzymatic properties of Pectinase XXL were described, and the results showed that the enzyme had a good acid stability and thermal catalytic characteristics. The juice extraction experiment proved that the enzyme could significantly improve the juice yield and light transmittance of plantain, and reduce the viscosity of plantain. Thus, Pectinex XXL has potential in industrial plantain juice production.
