Fibrils of γ‐Oryzanol + β‐Sitosterol in Edible Oil Organogels

Abstract

Mixtures of c-oryzanol and b-sitosterol are able to form transparent organogels in edible oils. Small-angle X-ray scattering was used to elucidate the microstructure of the building blocks of these organogels in sunflower oil. It was found that the plant sterol(ester)s form hollow tubes with a diameter of 7.2 ± 0.1 nm. Tubes prepared with coryzanol-rich structurant show the least bundle aggregation, and can be supercooled during formation most easily. The tubes melt at elevated temperatures, in agreement with the loss of structuring capacity as observed in earlier experiments.Keywords Organogel Á Phytosterol Á Self assembly Á Fibril Á X-ray diffraction (XRD) Á Small-angle X-ray scattering (SAXS) Á Wide-angle X-ray scattering (WAXS) Á Differential scanning calorimetry (DSC)

Effect of Sterol Type on Structure of Tubules in Sterol + γ-Oryzanol-Based Organogels

“…18 A recent publication presented evidence from small-angle X-ray scattering (SAXS) that the mixture of γ-oryzanol with β-sitosterol forms tubular structures in TAG oils. 19,20 The diameter of these tubules was found to be of the order of only 7 nm, and this small diameter explains the optical properties of the (slightly hazy) transparent oil gels that form. Recently, microscopic images have confirmed the existence of tubules in closely related systems, 21 and similar results were obtained by atomic force microscopy (Kirkland and Yakubov, 2009, unpublished data).…”

Emulsion Gels in Foods

“…As a consequence, the aggregate does not form a perfectly straight one-dimensional crystallite but, instead, the assembly curves somewhat, much like a staircase. On a supramolecular length scale this leads to the formation of a helical ribbon in triglyceride oil [25]. The resulting tubules aggregate into a firm ''organogel'' network [26].…”

Food Functionality and the Physics of Bionanotechnology: Some Examples and Challenges

“…Recently, mixtures of specifi c plant sterol s and plant sterol esters have been shown to form nanotubes in edible oil [30] . This structuring allows one to solidify oils that do not show gelation at regular temperatures due to the fact that they contain many polyunsaturated fatty acid s ( PUFA s).…”