Pectin methyl esterase activation

Wood, P.J. and Siddiqui, l.R. 1971. Determination of methanol and its application to the measurement of pectin ester content and pectin methyl esterase activity. Anal. Biochem. 39 418-428. 

The occurrence of unwanted side activities in commercial pectinase preparations has been reported, and represents one of the main problems associated with their use in winemaking. Notably, increased formation of methanol during fermentation has been observed in association with pectinase treatment of the juice, due to pectin-methyl esterase activity (Revilla and Gonzdlez-SanJose 1998). Cinnamyl esterase... 

Giner-Segui et al. (2006) studied the evolution of polygalacturonase (PG) (EC 3.2.1.15) activity in aqueous solution of commercial enzyme preparation. Up to 76.5% reduction of the PG activity could be achieved at 38 kV cm and 1100 J,s EF intensity and treatment time, respectively. However, an enhancement of PG activity at soft PEF treatment conditions (up to 110.9% at = 15kV cm and 300 J,s) was observed. A maximum of 80% of pectin methyl esterase activity in orange juice was inactivated at 35 kV cm and 1500 J,s EF strength and treatment time, respectively (Elez-Martinez et al., 2007). 

Elez-Martmez, P., Suarez-Recio, M., and Martfn-Belloso, O. 2007. Modeling the reduction of pectin methyl esterase activity in orange juice by high intensity pulsed electric fields. Journal of Food Engineering 78 184—193. 

Schols and Voragen, 2002). Other substrates, such as citrus pectin, may be used in some cases, but overall PGase activities will probably be lower on the esterified pectins, and results from assays using the esterified pectins are more likely to be influenced by non-PGase enzymes, particularly pectin lyase and pectin methyl esterase (see Commentary). 

In strawberry puree, pressurization above 250 MPa generated a poly-phenoloxidase activity loss of 60%, while peroxidase activity decreased in 25% with pressures above 230 MPa. A combination of temperature and pressure reduced the activity of pectin methyl esterase in orange juice by up to 50% (Cano et al., 1997). As shovm by Basak and Ramaswamy (1996), the inactivation of pectin methyl esterase in orange juice depends on pressure level, time of treatment, pH, and soluble solids content. In Satsuma mandarin juice, 300-400 MPa for 10 min was required to partially inactivate the pectin methyl esterase, which was reactivated neither after treatment nor during storage. This demonstrated that the greater the concentration of soluble solids in the medium the lower the inactivation of the enzyme (Ogawa et al., 1990). 

Pectin methyl esterase in juices requires processing times of 10 min combined with pressures of 600 and 1000 MPa and temperatures of 57 and 20°C, respectively. These combinations prevent microbial deterioration, but must be combined with a mild blanching, refrigerated storage and addition of inhibitory enzymes to achieve a stable product with respect to pectin methyl esterase (Cheftel, 1992). Guava puree samples were treated with pressures of 400 and 600 MPa looking for pectinesterase and pol)q)henoloxidase inactivation. The residual activity of the former was greater than 76%, while of the latter was above 63% at the lower pressure. 

Yeom, H.W., Streaker, C.B., Zhang, Q.H., and Min, D.B. 2000b. Effects of pulsed electric fields on the activities of microorganisms and pectin methyl esterase in orange juice. Journal of Food Science 65 1359-1363. 

Other enzyme studies (employing species of Pythium) have shown that Terrazole decreases the activity of exocellulase, increases that of endocellu-lase, and is substantially without effect on that of polygalacturonase and pectin methyl esterase.484 It partially inhibits the incorporation of uridine diphosphateacetylglucosamine into chitin in the presence of chitin synthetase, in vitro 485... 

Pectol5 ic activity of pectin lyase, pectin methyl esterase and polygalacturonase enzymes. 

The addition of pectolytic enzymes in crushed grapes can improve juice extraction for certain varieties very rich in pectic substances (Muscat, Sylvaner, etc.). Commercial preparations contain diverse enzymatic activities which are active at a low pH pectin methyl esterases, polygalacturonases, pectin lyases and hemicellulases. At a concentration of 2-4 g/hl, 15% more juice can be obtained during a settling period of 4-10 hours even a shorter settling period (1-2 hours) increases the proportion of free run (Table 11.8). Effectiveness varies according to the nature of the grapes. 

Klein, J. D., Hanzon, J., Irwin, P. L., Shalom, N. B., and Lurie, S. (1995). Pectin esterase activity and pectin methyl esterification in heated Golden Delicious apples. Phytochemistry 39, 491-494. 

Each fruit has specific quantities and ratio of pectin, hemicelluloses and cellulose. These polysaccharides are important concerning enzymes activities required to produce juices and concentrates. Moreover, even if molecular weight and methylation degree of the pectin are specific for each fruit, during the fruit maturation, endogenous pectinases depolymerases and esterase are changing the pectin characteristics This broad variability of raw material makes difficult the standardisation of fruits processing. 

To find a suitable enzyme to catalyze the transesterification reaction (methyl ester to glycerol ester) under mild conditions, we screened a number of lipases and esterases. We found two lipases (Candida cylindracea lipase and porcine pancreatic lipase) to exhibit catalytic activity for this reaction. The reaction conditions entailed elevated temperatures, with the use of glycerol as the solvent and an acyl acceptor. The enzyme catalyzed the esterification of the carboxyl group of the pectin to the Cl (primary) alcohol of the glycerol to form the monoester. No substantial glycerol... 

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