Ripening-related changes in the cell walls of olive (Olea europaea L.) pulp of two consecutive harvests

Abstract

Olive fruits, harvested in two consecutive seasons at green, cherry and black stages, were used to study compositional changes in the cell walls during ripening. Ripening-related changes in both harvests were characterised mainly by an increase in the solubilisation of pectic and hemicellulosic polysaccharides, an increase in the relative amount of arabinose in pectic polysaccharides and a decrease in the degree of methylesterification of pectic polysaccharides. Further to degrading processes, the data obtained suggest the synthesis of new polysaccharides. The analysis of olive cell wall phenolics showed mainly the presence of p-coumaric acid, which increased in one harvest, whereas in the other the values did not differ. The samples of the second harvest, although presenting green, cherry and black colours, had less distinct ripening characteristics than those of the previous harvest. Different activity levels of polyphenol oxidase, polygalacturonase and pectin methylesterase might have contributed to the differences observed between the two harvests. The results showed the distinct extension of ripening-related changes in the cell walls of the two harvests, indicating that the olive colour, although characteristic of the stage of ripening, cannot be strictly used for its evaluation and definition. Copyright © 2006 Society of Chemical Industry