Thermal inactivation kinetics of partially purified mango pectin methylesterase

Abstract

Kinetic parameters of thermal inactivation of pectin methylesterase (PME) in a partially purified mango enzyme extract were determined. The PME of mango partially purified by salting out showed different patterns of thermal inactivation, indicating the presence of a thermostable fraction at 70 °C and a thermolabile fraction at lower temperatures. The inactivation of the thermostable fraction exhibited a linear behavior that yielded a z-value of 9.44 °C and an activation energy (Ea) of 245.6 kJ mol -1 K -1 using the Arrhenius model. The thermostable mango PME fraction represented 17% of total crude enzyme extract, which emphasizes the importance of residual enzyme activity after heat treatment.

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“…The presence of thermolabile and thermostable fractions of mango PME was reported previously by Labib et al (1995). In order to avoid the effects of the thermolabile fraction a procedure was applied to the mango E-PME consisting of a isothermal treatment at 70 °C by traditional heating (warm water bath) according to the report by Diaz-Cruz et al (2016). Figure 1 shows the inactivation kinetic of E-PME where the inactivation of the thermolabile and thermostable fraction were measured.…”

“…La existencia de fracciones termolábiles y termo estables de PME de mango fue reportada con anterioridad por Labib et al (1995). Para evitar los efectos de la fracción temolabil se procedió a aplicar a la E-PME de mango un tratamiento isotérmico a 70º C por calentamiento convencional (baño maría) de acuerdo a lo reportado por Diaz-Cruz et al (2016). La Figura 1 muestra la cinética de inactivación donde se mide la inactivación de la fracción termolábil (antes de los 10 minutos) y la fracción termoestable posterior a este tiempo.…”

“…Los procesos térmicos aplicados en frutas como mango tienen como objetivo pasteurizar pero también inactivar enzimas (Lewis & Heppell, 2000;Diaz-Cruz et al, 2016).…”

“…The applied thermal processes in fruits, such as the mango, have been to pasteurize them but also to inactivate enzymes (Lewis & Heppell, 2000;Diaz-Cruz et al, 2016).…”

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“…The presence of thermolabile and thermostable fractions of mango PME was reported previously by Labib et al (1995). In order to avoid the effects of the thermolabile fraction a procedure was applied to the mango E-PME consisting of a isothermal treatment at 70 °C by traditional heating (warm water bath) according to the report by Diaz-Cruz et al (2016).…”