Pectin heterogeneity

In contrast, acid-extracted pectins were eluted as a wider peak for a higher ionic stength in agreement to their lower dm. The peak is also much more heterogeneous. 

Ultrafiltration of heterogenous colloidal suspensions such as citrus juice is complex and many factors other than molecular weight contribute to fouling and permeation. For example, low MW aroma compounds were unevenly distributed in the permeate and retentate in UF in 500 kd MWCO system (10). The authors observed that the 500 kd MWCO UF removed all suspended solids, including pectin and PE. If PE is complexed to pectate in an inactive complex, then it is conceivable that release of PE from pectin with cations will enhance permeation in UF. At optimum salt concentration, less PE activation was observed at lower pH values than at higher pH (15). In juice systems, it is difficult to separate the effect of juice particulates on PE activity. Model studies with PE extracts allows UF in the absence of large or insoluble particulates and control of composition of the ultrafilter. In... 

The intermediate-mobility pectin can exist in any space in the cell wall more than 2nm away from cellulose microfibrils. It could therefore be in the middle lamella, cell comers or between layers of microfibrils in addition to the above proposal. The pectin seen in this part of the spectram are probably a heterogeneous mixture from a number of locations. 

The ripening process has been subject of many studies [2,6,8]. Due to the large variety of plant tissues investigated, the results of these studies are quite heterogeneous. In general an increase in water-soluble pectins is observed, which is related to the combined action of... 

Fractionation of Pectic Polysaccharides. A number of complex polysaccharides differing in their physical and chemical characteristics are found in pectin. This heterogeneous nature of pectin has been reviewed earlier. In order to characterize these... 

In our study, formation of isoluble complexes between pectin, a heterogeneous mixture of a number of neutral and acidic polysaccharides, and lipoprotein was studied. The basic limitation with the formation of insoluble complexes is that it is difficult to quantitate the said interaction. Furthermore, the observed interaction between pectic polysaccharides and lipoprotein is at a pH which is not physiological. We, therefore, are attempting to study this interaction under physiological conditions and by use of buffer systems which are devoid of cations, in order to facilitate formation of soluble complexes. In addition, by using labelled pectic polysaccharides, studies resulting in the elucidation of kinetics, specificity and nature of the interaction between labelled pectic polysaccharides and lipoprotein will be performed. 

Berth, G. (1988). Studies on the heterogeneity of citrus pectin by gel-permeation chromatography on Sepharose 2B/Sepharose 4B. Carbohydr. Polym. 8 105-117. 

Specific enzymatic degradation has been useful in determining the structures of pectins, gums and other plant polysaccharides (115), the mucopolysaccharides of higher animals (116), and other complex carbohydrates (117) including those from microorganisms 118, 119, 120). In these heterogeneous polymers enzyme treatment is most useful for deter-... 

Figure 3.4 shows the structures of pectin and cellulose. Also shown arc the sugars that make up the polysaccharide backbone and side chains of the heterogeneous compound hemiceJIulose. 

Hourdet, D. and Muller, G. 1991. Solution properties of pectin polysaccharides—HI molecular size of heterogeneous pectin chains. Cahbration and application of SEC to pectin analysis, Carbohydrate-Polymers, 16(4) 409-432. 

Kirtchev, N., Panchev, I. and Kratchanov, C. 1989. Kinetics of acid-catalyzed deesterification of pectin in a heterogeneous medium, Int. J. Food Sci. Technol., 24 479-486. 

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