Material properties of concentrated pectin networks

• Published in: Carbohydrate research Vol. 339; no. 7; pp. 1317 - 1322
• Main Authors: Zsivanovits, Gabor, MacDougall, Alistair J., Smith, Andrew C., Ring, Stephen G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 17.05.2004
• Subjects: calcium; cations; Cations - chemistry; Cell Wall - chemistry; cell walls; Film-forming; Hydration; Ions; magnesium; Mechanical properties; Network; Osmolar Concentration; Osmotic Pressure; Pectin; pectins; Pectins - chemistry; Plant cell walls; Plants - chemistry; Polyethylene Glycols - chemistry; potassium; Hydration; Film-forming; Network; Mechanical properties; Ions; Pectin; Plant cell walls
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/j.carres.2004.02.027

Pectin films were allowed to hydrate, at constant osmotic stress, to produce pectin networks of a concentration similar to that found in the plant cell wall. The observed swelling of the film was dependent on counterion type and concentration. The tensile modulus of the film increased with decreasing swelling. We have examined the mechanical behaviour of different types of pectin at high concentrations (>30% w/w), relevant to the behaviour of pectin in the plant cell wall, and as a film-forming agent. Mechanical properties were examined as a function of counterion type (K +, Ca 2+, Mg 2+), concentration and extent of hydration. Hydration was controlled in an osmotic stress experiment where pectin films were exposed to concentrated polyethylene glycol [PEG] solutions of known osmotic pressure. We investigated the mechanical behaviour under simple extension. The results show that the swelling and stiffness of the films are strongly dependent on pectin source and ionic environment. At a fixed osmotic stress, both Ca 2+ or Mg 2+ counterions reduce swelling and increase the stiffness of the film.