Pectin methyl esterase, enzymatic

Fig. 10. Intercellular junction zones of carrot cells grown in suspension have been observed in electron microscopy after immunogold labeling with the 2F4 antibody, (a) no treatment of the sections prior to labeling the gold particles are restricted to the center of the junction zones (b) enzymatic (pectin methyl esterase) deesterification of the E.M. grids before labeling the deesterified pectins present in the primary walls now bind the probe. Scale bars = 1 pm.

Pectinesterase action was first reported in 1840 by Fremy (56). He noted that the addition of carrot juice to a pectin solution caused formation of a gel. This gel was produced by the enzymatic deesterification of pectin followed by precipitation of the resulting polygalacturonic acid as calcium pectate 20), Various names such as pectin meth-oxylase and pectin methyl esterase have been applied to the enzyme, but pectinesterase is the preferred trivial name (57). 

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. 

For bUayer formation in emulsions in a first set of experiment, commercially available pectin samples were used [51 ]. To get a deeper understanding of the impact of molecular structure of the pectin on the functionality of the bilayer-stabilised emulsions, pectin samples with well-defined degree of methoxylation and distribution of these groups were produced on the lab scale. Enzymatic demethoxylation was performed in a similar way using either a commercially available fungal pectin methyl esterase or plant-derived pectin methylesterase, which was isolated from orange peel as described in Stoll et al. [52]. Commercially available high... 

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