Calcium-mediated gelation of an olive pomace pectic extract

• Published in: Carbohydrate polymers Vol. 52; no. 2; pp. 125 - 133
• Main Authors: Cardoso, Susana M, Coimbra, Manuel A, Lopes da Silva, J.A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2003; Elsevier Science
• Subjects: Applied sciences; Exact sciences and technology; Gelation; Natural polymers; Olive pomace; Pectic polysaccharide; Physicochemistry of polymers; Starch and polysaccharides; Viscoelastic properties; Viscoelastic properties; Pectic polysaccharide; Gelation; Olive pomace; Viscoelasticity; Molecular structure; Phase diagram; Experimental study; Solvent extraction; Pectic substance; Calcium ion; Plant origin; pH; Oside polymer; Olive husk; Hydrogel; Aqueous solution; Saline solution
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/S0144-8617(02)00299-0

Pectic raw material was extracted from the alcohol insoluble residue of olive pomace. After purification, the olive pectic extract (OPE) contained 48% of galacturonic acid (GalA) and 31% of arabinose, in a total sugar content of 72%, and a degree of methylesterification (DM) of 43%. Phase diagrams were established to define the physical state of the OPE/calcium systems, at pH 3 and 7, as a function of GalA and calcium concentration. The rheological properties of the OPE/calcium systems were investigated by small-amplitude oscillatory tests. Kinetics of gel ageing and the viscoelastic properties of the cured gels were evaluated as a function of GalA and calcium concentration at pH 3 and 7. Compared with the observed behaviour of a citrus pectin, taken as representative of a commercial low-methoxyl pectin, the OPE showed higher critical GalA and calcium concentrations for gelation to occur, a larger region corresponding to homogeneous gel, and gels characterised by lower viscoelastic moduli, at similar GalA and calcium concentrations.