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Cell-wall metabolism of 'Arbequina' olive fruit picked at different maturity stages

Lara, I., Albrecht, R., Comabella, E., Riederer, M., Graell, J.
Acta horticulturae 2018 no.1199 pp. 133-138
Olea europaea, alpha-N-arabinofuranosidase, beta-galactosidase, chemical bonding, color, enzyme activity, maturity groups, maturity stage, mechanical damage, metabolism, olives, pectins, pericarp, ripening, sodium, uronic acids
Information on cell-wall metabolism during ripening of intact fruit of olive (Olea europaea L.) is scarce, despite the impact of cell-wall properties on fruit susceptibility to mechanical damage, infestations or rots. In this work, 'Arbequina' fruit were picked and classified into five maturity groups according to external colour. Cell-wall materials were isolated from the fruit pericarp as alcohol-insoluble residue (AIR), fractionated and analysed, and a range of cell-wall-modifying enzyme activities were measured. AIR content increased sharply at stages 2 and 3, in parallel with fruit expansion. Yields of the sodium carbonate-soluble fraction, enriched in covalently bound pectins, decreased after stage 4, along with a sharp decline in the ratio of neutral sugars to uronic acids, which suggests substantial loss of neutral sugars from pectin side-chains. The activities of α-l-arabinofuranosidase (AFase) and, to a lesser extent, β-galactosidase (β-Gal) increased simultaneously, consistent with the possible contribution of the loss of pectin-bound arabinosyl and galactosyl residues to the ripening-related softening of fruit.