Pectic materials

PEC-1000 Pechmann reaction Peclet numbers PE coatings Pectic acid Pectic acids [9046-40-6] Pectic materials Pectic substances Pectin... 

Raw material Cellulose, % Hemicellulose, % Lignin, % Pectic material, % Extractives, % Reference... 

Through a -based spectral editing procedure we found some pectic material spatially located near cellulose. This included some eggbox pectin. Pectic material was also located more than 2nm away from cellulose. 

The role of pectin in plant physiology is still far from clear. It is considered by some to be a cementing material but it is evident that the various types of pectic materials are able to perform in plants exceedingly varied biological functions. 

F. Ehrlich was one of the first workers to attempt a detailed chemical investigation of pectin.80 He subdivided pectic materials into groups ... 

More recently, the chemical structure of the components of pectic materials has been investigated by the present writers, whose approach... 

We may return now to the polysaccharides present in the peanut for a brief consideration of the relationship of the other components present in the pectic materials to the araban constituent. All the evidence indicates that the pectic acid portion of the peanut is identical with normal pectic acid and, as was indicated in the previous section, this material, which is very stable to acid hydrolysis and possesses a high positive rotation contains a main chain which is built up of D-galac-turonic acid residues of the pyranose type. If, therefore, the araban associated with the pectic acid had been derived directly from the pectic acid by decarboxylation without intermediate hydrolysis of the poly-galacturonide, the sugar residues in the araban should also be in the pyranose form. The experimental evidence shows clearly, however, that the arabinose residues in araban are furanose in type and it follows that any hypothesis concerning the direct conversion of pectic acid into the araban by decarboxylation is untenable. 

Although pectic materials are known to be present in wood, it is not clear whether this e-galactan is a component of wood pectin, and in view of the wide difference in structure between this galactan and the one associated with pectin in lupin seeds, further investigations of this point will be awaited with special interest. 

Alternatively, if we suppose that the hexose polysaccharide is produced first and is then transformed into pectic acid and araban, at least two types of galactan, other than the one already isolated from pectic materials, would be required to account for the types of structure present respectively in pectic acid and araban. This would seem to be somewhat unlikely since, on this view, one would expect to encounter other types of pectic acid and araban, whereas on the evidence now available the pectic acid isolated from all samples of pectic materials examined appears to be the same, and a similar conclusion applies in the case of the araban. 

It is clear, however, that the extensive problems concerning phytochemical relationships which have been raised as the result of the work summarized in this review cannot be resolved in the present state of knowledge. So far, in spite of the considerable attention given by many workers in this difficult field, little more than a preliminary survey of the possibilities has been achieved. Further investigations, which will almost certainly require novel methods of approach, will be necessary in order to decide unequivocally the structural formulas of the components of pectic materials, and only when such further knowledge is available will it be feasible to reach definite conclusions regarding their phytochemical relationships. 

Uronic acids and pectic material have partly or mainly been dissolved and removed from commercial boards on pressurized refining. On heating wood they will contribute considerably to CO2 release (33). Organic acids such as formic and acetic acid are also split off from side chains of wood polymers. 

In contrast, a comparatively small proportion of recent researches dealing with the enzymes acting on pectic materials proceeded on classical lines involving purification and constitutional studies. With the exception of a few papers, most reports deal with the action and behavior of these enzymes without extensive purification and paying little attention to the chemical composition and constitution of the enzymes themselves. The reason for this might be the general preoccupation with the development of suitable methods for the exact determination of the action of pectic enzymes, which in turn is the result of our lack of knowledge of the exact structure of pectic substances. 

The subject of pectic enzymes has been previously reviewed by the senior author3 and others4 and therefore this article will be confined to advances made during the past decade. Although the chemistry of pectic materials has been dealt with in a previous volume of this series by Hirst and Jones,6 we feel that a short review of the general status of pectin chemistry and especially of nomenclature is needed here to facilitate later discussions. 

Part of this objection to the calcium pectate as a means of following the hydrolysis of pectic materials can be met by using the simple procedure developed by Fellers and Rice" for the estimation of pectic substances as pectic acid. This approximate method measures the volume of the pectic acid which can be produced from a sample of soluble pectic material and will therefore show the loss of colloidality by the rapidly decreasing volume even if the weight of the precipitate remains the same. Unfortunately the Fellers-Rice method is not sufficiently accurate for exact kinetic studies. 

Taylor H. Evans and Harold Hibbert, Bacterial Polysaccharides 203 E. L. Hirst and J. K. N. Jones, The Chemistry of Pectic Materials 235 Emma J. McDonald, The Polyfructosans and Difructose Anhydrides 253 Joseph F. Haskins, Cellulose Ethers of Industrial Significance. 279... 

Peat, Stanley, obituary of, 25, 1-12 Pectic materials, chemistry of, 2, 235-251 enzymes acting on, 5, 79-102 Pentitols,... 

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