Solubilization of Cell Wall Polysaccharides from Olive Fruits into Treatment Liquids during Spanish Green Olive Processing

Abstract

During Spanish green olive processing, several samples of fruits and liquids were taken. Cell walls of olive fruits were isolated and fractionated, and the liquids were analyzed by HPLC. During the lye treatment and wash, an exchange of arabinans from carbonate-soluble and 4 M KOH-soluble fractions to the water-soluble was observed, and a partial solubilization into the liquids was quantified (the average molecular weight of portions solubilized was 6 kDa). The main change in pectins was a movement of homo- and rhamnogalacturonans from water-soluble and carbonate-soluble fractions to the imidazole-soluble fraction during lye and wash due to high pH, but another minor one occurred: a partial solubilization of alkali-soluble and cellulose-linked pectins during lye treatment, wash, and fermentation. Around 3 mg/fruit of cellulose was also solubilized, mainly during lye and wash. Only a small part of this was recovered as oligo- and/or polysaccharides of molecular weight >1000 kDa. A very accurate balance wa...