The contribution of high pressure carbon dioxide in the inactivation kinetics and structural alteration of myrosinase

Abstract

High pressure carbon dioxide (HPCD) has been verified to be an efficient way of inactivating enzyme activity. This work investigates the influence of temperature (T), pressure (P), exposure times (t) on the activity of commercial myrosinase (MYR) submitted to HPCD. Results showed that only 1.00% of MYR activity retained at 22 MPa and 65°C for 5 min. Moreover, the first-order reaction kinetic data of MYR inactivation as influenced by pressure of HPCD were analysed. With the pressure rising from 8 to 22 MPa at 55°C, the inactivation rate constant (k) increased from 0.015 to 0.024 min )1 , while the decimal reduction time (D) decreased from 157.2 to 96.1 min. Additionally, a series of exploratory experiments were conducted to investigate the contribution of the HPCD parameters (T, P and CO 2 dissolution), with analysing circular dichroism spectroscopy and tryptophan fluorescence spectra, illustrate that CO 2 dissolution plays a dominant role in MYR inactivation and structural alteration.

Inactivation kinetics of polyphenol oxidase using a two-stage method with low pressurized carbon dioxide microbubbles

“…Many researchers have recognised that the enzyme inactivation efficiency of an SC-CO 2 treatment is enhanced by increasing the temperature and pressure (Yoshimura et al, 2001(Yoshimura et al, , 2002Tanimoto et al, 2005;Liu et al, 2008Liu et al, , 2010Zhi et al, 2008;Zhang et al, 2010;Yang et al, 2011). In addition, our results agreed with those of Fadíloglu and Erkmen (2002) where lipase activity was lower with CO 2 treatment at atmospheric pressure than that with heat treatment.…”

Effects of High-Pressure CO2Processing on Flavor, Texture, and Color of Foods

“…Volatile compounds could be stripped off by CO 2 during HPCD decompression and supercritical extraction (Supercritical CO 2 was CO 2 at a temperature and pressure above its critical point values: T c = 31.1 • C, P c = 7.38 MPa). In fact, HPCD was reported to be used to the removal of the undesirable flavor of the pigment extracts from crucifer plants (Liao et al, 2008;Yang et al, 2011). Low-molecular-weight compounds were easily lost than high-molecular-weight compounds, different kinds of food products had different volatile compounds, so there were Downloaded by [Laurentian University] at 18:54 07 December 2014…”

“…2 (Casey et al, 1996). Yang et al (2011) reported the residual myrosinase in HPCD-treated red cabbage catalyzed the glucosinolates into the odorous products such as isothiocyantes. Chen et al (2010) also found that the lipoxygenase activity influenced the volatile flavor of hami-melon juice, especially after storage for four weeks.…”

Recovery of antioxidant and antiproliferative compounds from watercress using pressurized fluid extraction

“…When comparing the results obtained for both extracts, a signicant decrease in total ITCs and PEITC yields was observed when a longer static period was applied (P < 0.05). According to Yang et al (2011), due to the dissolution of CO 2 and consequent variation of pH value, there is a signicant reduction of b-thioglucoside glucohydrolases activity and alteration of structure aer high pressure carbon dioxide treatment. 43 Moreover, Ohtsuru and Kawatani (1979) established that wasabi myrosinase optimum pH was about pH 6.5/7.0 and that the enzyme was not stable at acidic pH values.…”

“…According to Yang et al (2011), due to the dissolution of CO 2 and consequent variation of pH value, there is a signicant reduction of b-thioglucoside glucohydrolases activity and alteration of structure aer high pressure carbon dioxide treatment. 43 Moreover, Ohtsuru and Kawatani (1979) established that wasabi myrosinase optimum pH was about pH 6.5/7.0 and that the enzyme was not stable at acidic pH values. 44 In this work, the effect of pressure in hydrolysis of GLs to ITCs was studied by incubating the sample (G) at atmospheric pressure with the same moisture content (125% d.b.)…”