Temperature–time relationships for thermal inactivation of pectinesterases in orange juice

Abstract

The first-order kinetic model of a two-component system was applied to calculate the necessary parameters using the commercial Mathcad program package during the experimental thermal pasteurisation of Valencia orange juice. Thermostable and thermolabile pectinesterases, accounting for 6.6 and 93.4% of the total enzyme population in the juice respectively, showed a 5.63°C Z s value and a 9.54°C Z l value respectively from the thermal destruction curves at temperatures ranging from 75 to 90°C. The calculated Z s values were consistent with the literature values for Valencia orange juice. The calculated and experimental non-linear thermal pasteurisation curves for orange juice were also in good agreement at temperatures between 75 and 90°C.

Impacto del tratamiento por pulsos eléctricos de alta intensidad y altas presiones hidrostáticas sobre la calidad y seguridad microbiológica de un alimento mezcla de zumo de naranja y leche

“…Approximately 4-5 % of the PME remained after the 90 °C treatment. Several authors (Veersteg et al, 1980;Wicker and Temelli, 1988;Snir et al, 1996;Cameron et al, 1996;Tajchakavit and Ramaswami, 1997;Cameron et al, 1998;Lee et al, 2003;Do Amaral et al, 2005) have also observed a residual activity after thermal treatment, considered the stable fraction, between 4-8.3% in Navel and Valencia var. oranges reflecting the thermotolerance of the orange PME.…”

“…However, in the case of different enzymes thermal inactivation curves have been observed to behave differently due to the presence of different fractions exhibiting different stabilities (Hou et al, 1997;Lee et al, 2003; INTRODUCTION 50 Tajchakavit and Ramaswamy, 1997; Van den Broeck et al, 1999 a; Wicker and Temelli, 1988;Cameron et al, 1998;Han et al, 2000; Versteeg et al, 1980). Nevertheless, in many cases only part of the curve (activity related to the most abundant fraction) has been modelled to obtain the previously described parameters.…”

“…The percentage (6-8%) of stable fraction estimated was in line with data obtained by several authors (4-8.3%) in different varieties of oranges (Navel and Valencia var.) (Cameron and Grohmann, 1996;Cameron et al, 1998;Do Amaral et al, 2005;Lee et al, 2003;Snir et al, 1996;Tajchakavit and Ramaswamy, 1997;Versteeg, et al, 1980;Wicker and Temelli, 1988). It has been stated that the amount of orange PME stable fraction is variable and depends to a large extent on the orange variety used and the time of harvest (Snir et al, 1996).…”

“…There are a number of studies available on the heat inactivation of PME in orange juice (Versteeg et al, 1980;Tajchakavit and Ramaswamy, 1997;Lee et al, 2003), in orange pulp (Wicker and Temelli, 1988) as well as on the purified enzyme isolated from oranges (Cameron et al, 1994;Cameron and Grohmann, 1996;Van den Broeck et al, 1999 a;Han et al, 2000). HHP inactivation of purified PME has been studied in buffer systems ( Tajchakavit and Ramaswamy, 1997; Van den Broeck, et al, 1999 a;Lee, et al, 2003), four fractions with different thermostability (Cameron et al, 1998) and seven fractions in the peel (Han, et al, 2000).…”

“…HHP inactivation of purified PME has been studied in buffer systems ( Tajchakavit and Ramaswamy, 1997; Van den Broeck, et al, 1999 a;Lee, et al, 2003), four fractions with different thermostability (Cameron et al, 1998) and seven fractions in the peel (Han, et al, 2000). In the case of orange juice Navel var.…”