Thermoresistance of pectin methylesterase in Sanguinello orange juice

The behavior of pectin methylesterase (EC 3.1.1.11) activity as a function of temerature was investigated in Sanguinello orange juice. The thermal ina ctivation of this enzyme was evaluated in the range of 75-95C and was found to be non-linear. Due to very low activity content, after the thermal trea tment at temperatures above 80C, the active enzyme was concentrated by affi nity chromatography The logarithmic values of decimal reduction times, plot ted against temperature, showed a nonlinear pattern featuring a sudden chan ge in slope at temperatures exceeding 85C. The z value determined in the ra nge 85-95C was much higher than that calculated in the range 75-85C. The de cimal reduction times were used to estimate the times of treatment for the enzyme inactivation during a HTST process.