Molecular Weight and Ionic Characteristics of Olive Cell Wall Polysaccharides during Processing

Abstract

The changes that occur during olive fruit (Olea europaea arolensis) processing (high pH treatment and fermentation) in the pectic fractions and hemicelluloses B of the cell wall have been studied. The amount of neutral arabinans in the cell wall and the composition of this fraction did not change, but there was a great decrease in the molecular weight [from higher than 400 000 in unprocessed fruit (UF) to 70 000 in processed fruit (PF)]. The water-soluble acidic polysaccharides almost disappeared, losing mainly their galacturonic acid-rich portions. The most important change that occurred in the oxalate-soluble rhamnogalacturonans was a decrease in their degree of esterification (from 75.44% and 35.42% for the peaks in UF to 28.42% for the peak in PF). Their composition and molecular weight were not greatly affected by processing. The molecular weights of the main polysaccharide components of the hemicelluloses B (xyloglucans, galactoglucomannans, and arabinoxylans) decreased greatly, although their sugar compositions remained almost stable.

Diffusion of glucose and sodium chloride in green olives during curing as affected by lye treatment

“…The lye treatment disorganizes the cytoplasmic membranes and causes the rupture of chemical links in hemicellulosic and pectic polysaccharides, as well as the de-esterification of pectins in the middle lamella of the cell walls, increasing dramatically the charge density of the pectic chains due to the free carboxyl groups (Jiménez, Guillén, Sánchez, Fernández-Bolañ os, & Heredia, 1995;Jiménez, Guillén, Sánchez, Fernández-Bolañ os, & Heredia, 1996;Jiménez, Guillén, Fernández-Bolaños, & Heredia, 1997;Jiménez, Heredia, Guillén, & Fernán-dez-Bolaños, 1997), creating a net negative charge on the molecules causing repulsion between individual pectic chains (Sánchez Romero, Guillén, Heredia, Jiménez, & Fernández-Bolañ os, 1998).…”

“…This repulsion could be reinforced by the high pH of the processing liquids that would ensure a total ionization of the carboxyl groups (Jiménez et al, 1995(Jiménez et al, , 1996. This conformational change could probably explain the decrease in tortuosity facilitating the diffusion of sugars out of the olives.…”

A simple model of the diffusion phenomena taking place during the debittering process of green table olives

“…The changes in texture and solubilization of cell wall polysaccharides during the processing of Spanish green olives have been extensively studied by different researchers (Jiménez et al, 1995(Jiménez et al, , 1996(Jiménez et al, , 1998Coimbra et al, 1996). They observed a marked decrease in texture during lye treatment and washing and a noticeable increase after soaking the olives in brine.…”

Effect of dry‐salt processing on the textural properties and cell wall polysaccharides of cv. Thasos black olives

“…3 The majority of the bibliographic data on this subject concerns olives in brine, usually produced by maintaining the fruits in a solution of 40-120 g L −1 sodium chloride for several months. In this context, Jiménez et al 4 showed that green Spanish olives had a significant texture increase when brining was performed after lye treatment (pH of flesh [11][12], but this effect was minimal when brining was carried out after the fermentation of the fruit (pH 3-4). For black olives, texture improvement after brining has been reported for the Hojiblanca variety undergoing the Californian process.…”