Changes in Texture and Cell Wall Polysaccharides of Olive Fruit during "Spanish Green Olive" Processing

Abstract

Olive fruits (Olea europaea cv. Arolensis Hojiblanca var.) were processed as Spanish green olives. The treatment included a first step at high pH (lye treatment), a lactic fermentation, and a final period of conservation in a high concentration brine. Four samples were taken in the critical moments of processing, and their cell wall material was isolated and fractionated into several groups of polysaccharides. Lye treatment had its biggest effect on uronic acid-containing fractions such as water (WSF), oxalate (OSF), and chlorite/acetic acid (DEL) soluble fractions. Marked changes were detected in the relative percentage of each of these fractions, suggesting interchange of polysaccharides (mainly homogalacturonans) between them. Fermentation, on the other hand, produced a marked degradation of neutral polysaccharides mostly from hemicellulose A (HA), hemicellulose B (HB), and α-cellulose (CEL), most likely by enzymatic action. Interchange of polysaccharides between these fractions may also occur. Conservation did not produce any change in the solubility characteristics or in the glycoside composition of the different polysaccharides. Texture decreased during the two first steps and did not change during the last one (conservation period).