Effect of Temperature and/or Pressure on Tomato Pectinesterase Activity

The activity of tomato pectinesterase (PE) was studied as a function of pressure (0.1−900 MPa) and temperature (20−75 °C). Tomato PE was rather heat labile at atmospheric pressure (inactivation in the temperature domain 57−65 °C), but it was very pressure resistant. Even at 900 MPa and 60 °C the inactivation was slower as compared to the same treatment at atmospheric pressure. At atmospheric pressure, optimal catalytic activity of PE was found at neutral pH and a temperature of 55 °C. Increasing pressure up to 300 MPa increased the enzyme activity as compared to atmospheric pressure. A maximal enzyme activity was found at 100−200 MPa combined with a temperature of 60−65 °C. The presence of Ca2+ ions (60 mM) decreased the enzyme activity at atmospheric pressure in the temperature range 45−60 °C but increased enzyme activity at elevated pressure (up to 300 MPa). Maximal enzyme activity in the presence of Ca2+ ions was noted at 200−300 MPa in combination with a temperature of 65−70 °C. Keywords: Tomato pectinesterase; thermal stability; pressure stability; kinetics; activation