Phenolic composition

The phenolic domain of the suberin polymer has not been well characterized. Early chemical studies on suberin from tree bark indicated that the polymer contains phenolics. Suberin from the cork of Pseudotsuga menziesii bark released phenolic acids (43% of extractive-free cork) and aliphatic acids (35%) upon saponification (180). Suberin, which was subjected to a limited saponification (2% KOH at room temperature) and successive solvent extraction with hexane. 

Family Genus/species Suberin content Depolymerization products Reference(s) 

A fraction analogous to BjOrkman lignin (39) was obtained when a portion of finely-powdered suberin polymer from the periderm of 5. tuberosum was solubilized with dioxane. This soluble fraction, however, was not enriched in either aromatic or aliphatic components over the insoluble residue (unpublished results). Other procedures from lignin chemistry - including refluxing in HCl/dioxane or HCl/dimethylformamide, and dioxane treatment at 160 C and high pressure (268, 396) - resulted in 20 o to 50% solubilization of the suberin preparation, but with each method the insoluble material contained the majority 

Initial studies, primarily done on suberin from the periderm of S. tuberosum give additional indication of the secondary structure of the polymer. Enriched preparations of suberin always contain high levels of carbohydrate (as much as 50 o). Obviously the suberin-enriched preparations contain covalently attached cell wall carbohydrates and the linkages between suberin and carbohydrate may be similar to those proposed for the attachment of lignin to carbohydrate (132, 268). Chemical studies on the polymer have shown that very few of the hydroxyl groups of cu-hydroxy acids are free and that the polymer has very few ( 5%) free aliphatic carboxyl moieties (230). Fractionation of S. tuberosum suberin by partial solubilization with 1 % HCl/dioxane has indicated that the aliphatic components may be in separate domains, for polymeric fractions that contained a larger proportion of fatty acids and fatty alcohols but a lower proportion of cu-hydroxy acids and dicarboxylic acids have been isolated. These fatty acids and fatty alco- 

The analysis by HPLC of phenolic compounds in peach fruit in our laboratory is done as follows. AU chemicals are reagent-grade products. Three separate batches of 5 g each of mesocarp tissue are blended in a mortar with 10 ml of 80% (v/v) acetone, and the homogenate is filtered through a Buchner funnel with suction. The three extracts are collected, centrifuged to dryness at below 30 °C, lyophilized and stored until analysis. After dissolution of the extract, 1 ml of 50% methanol is added to each sample, and the solution is centrifuged for 10 min at 12 000 g. Portions (2[rl) of the supernatant are separated into components by HPLC. Authentic phenolic compounds are analyzed also. The unknown com- 

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Industrial grade materials employ fillers such as asbestos, silica and glass fibre. These are incorporated by dry-blending methods similar to those used with woodflour-filled phenolic compositions. 

Some pertinent properties of the various polyester compounds are compared with those of a GP phenolic composition in Table 25.3. 

Table 8 Phenolic Composition of Natural and Technical CNSL...

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More nsnal vegetables were stndied by Nnntila et al. [358] who characterized onions and spinach for the phenolic composition, with and without previous hydrolysis. The authors performed the simultaneous determination of phenolic acids, flavonols, flavones glycosides, and cathechins. Fignre 19.9 reprodnces the separation obtained for the standard mixture in this study. 

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Perez-Magarino, S., Ortega-Heras, M., Cano-Mozo, E., and Gonzalez-Sanjose, M. L. (2009). The influence of oak wood chips, micro-oxygenation treatment, and grape variety on colour, and anthocyanin and phenolic composition of red wines. /. Food Compos. Anal. 22, 204-211. 

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