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Formation, structure, and rheological properties of ricinelaidic acid‐vegetable oil organogels
Author(s) -
Wright Amanda J.,
Marangoni Alejandro G.
Publication year - 2006
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-006-1232-9
Subject(s) - viscoelasticity , rheology , materials science , birefringence , kinetics , dynamic mechanical analysis , chemical engineering , canola , phase (matter) , polymer chemistry , chemistry , organic chemistry , polymer , composite material , optics , food science , quantum mechanics , engineering , physics
Vegetable oil‐based organogels were formed using ricinelaidic acid (12‐hydroxy‐9‐ trans ‐octadecenoic acid, REA). Gelation kinetics, gel structure, and stability were studied. Gelation occurred with as little as 0.5% (w/w) REA, depending on temperature and oil composition. Phase diagrams were constructed using canola, sesame, and DAG oils. Lower gelation tendencies were correlated with the presence of potential hydrogen‐bonding moieties in the oils. REA concentration had a significant influence on gelation kinetics and gel rheology. At 5°C, the 0.5% canola oil gel behaved like a weak, viscoelastic network composed of entangled strands. Between 1.0 and 5.0% REA, solid‐like, viscoelastic gels were formed. The 24‐hour G′ LVR (storage modulus in the linear viscoelastic region) was highly dependent on concentration and less so on temperature. Values for gelation time indicated a change in behavior below 2% REA and above 20°C. Polarized light microscopy revealed that the gels were formed through the interactions of long, thin, and birefringent fibers. Structural analysis using X‐ray diffractometry (XRD) indicated the presence of repeating REA dimers and increasing order with concentration and gel storage time. Increases in gel opacity, birefringence, XRD scattering, and fiber clustering were observed during storage.