Structural characteristics of pectic polysaccharides from olive fruit (Olea europaea cv moraiolo) in relation to processing for oil extraction

In the olive oil industry technical enzyme preparations are used as processing aids to improve the extraction yield and product quality. In order to obtain more insight in the mechanisms by which these enzyme preparations lead to a higher yield and a better quality, the effect of these preparations on the structure of the pectic polysaccharides present in the cell wall of olive fruit was investigated. Four pectin-rich fractions were isolated from the cell wall material of non-enzyme treated and enzyme treated olive fruit by successive extractions with cold buffer, hot buffer, chelating agents and diluted alkali and analysed. The results revealed that the use of technical enzyme preparations during processing mainly affected the pectic material present in the cold and hot buffer fractions. The structures of the arabinose-rich pectic polysaccharides solubilised by extraction with chelating agents and diluted alkali were barely affected by the use of enzyme preparations. The changes of the buffer soluble pectic material were reflected by a decrease in methyl esterification, a change in molecular weight distribution and a degradation of the (14)-linked galactan chains. No differences were observed in the composition of the arabinan chains. Also, the structural features of the polysaccharides present in the vegetation waters, the liquid by-product of olive processing, were studied. The sugar composition indicated the presence of mainly material of pectic origin in the vegetation waters. As a result of enzymatic processing the degree of methyl esterification decreased, the profile of the molecular weight distribution changed and the (14)-linked galactan chains were degraded as was also shown for the buffer soluble pectic polysaccharides

Structural characterisation of xyloglucan and xylans present in olive fruit (Olea europaea cv koroneiki)

Hemicellulose-rich fractions obtained from olive fruit were fractionated by anion-exchange chromatography, which resulted in a xyloglucan-rich pool and four xylan-rich pools. Sugar linkage analyses and degradation studies with specific enzymes were performed to obtain information about the structures. The results indicated a xyloglucan in olive fruit with a specific substitution pattern, which is not commonly found in plant cell walls: XXXG-type building units with both arabinosyl and galactosyl residues linked to it. The xylans present in olive fruit were all very low in substitution with mainly 4-O-methyl-glucuronic acid residues. Enzymatic degradation with endo-xylanases resulted in a mixture of neutral and acidic xylo-oligosaccharides. Striking were the identical degradation patterns on HPAEC for all xylan-rich pools while the elution of the pools on DEAE Sepharose differed markedly

Effect of enzyme treatment during mechanical extraction of olive oil on phenolic compounds and polysaccharides

The effect of the use of cell-wall-degrading-enzyme preparations during the mechanical extraction process of virgin olive oil on the phenolic compounds and polysaccharides was investigated. The use of the enzyme preparations increased the concentration of phenolic compounds in the paste, oil, and byproducts. Especially, the contents of secoiridiod derivatives such as the dialdehydic form of elenolic acid linked to 3,4-dihydroxyphenylethanol (3,4-DHPEA-EDA) and an isomer of oleuropein aglycon (3,4-DHPEA-EA), which have high antioxidant activities, increased significantly in the olive oil. Furthermore, the use of an N2 flush during processing strongly increased the phenolic concentration. Analyses of the pectic polymers present in the paste showed that the use of pectinolytic enzyme preparations increased the yield of the buffer soluble pectins and the proportion of molecules with a lower molecular mass. Also, the content of uronic acids in the buffer soluble extract increased considerably due to the use of the enzyme preparations. Analysis of the polymeric carbohydrates in the vegetation waters showed the presence of mainly pectic polymers. The addition of commercial enzyme preparations increased the uronic acid content of the polysaccharides in the vegetation water substantially compared to the blank. This study showed that the addition of cell-wall-degrading enzymes did improve the olive oil quality; however, mechanisms remained unclear