Light scattering | An-Najah Staff

The influence of the type of oil phase on the self-assembly process of γ-oryzanol + β-sitosterol tubules in organogel systems

Thu, 2013-02-14 14:46 — Hassan Ismaiel Sawalha (Manasra)

Journal Title, Volume, Page:

European Journal of Lipid Science and Technology , Volume 115, Issue 3, pages 295–300

Year of Publication:

2013

Link:

http://onlinelibrary.wiley.com/doi/10.1002/ejlt.201100395/abstract

Authors:

Hassan Sawalha

Chemical Engineering Department, An-Najah National University, Nablus, Palestine

Current Affiliation:

Chemical Engineering Department, An-Najah National University, Nablus, Palestine

[email protected]

Giel Margry

Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands

Ruud den Adel

Unilever Research and Development Vlaardingen, Vlaardingen, The Netherlands

Paul Venema

Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands

Arjen Bot

Unilever Research and Development Vlaardingen, Vlaardingen, The Netherlands

Eckhard Flöter

Unilever Research and Development Vlaardingen, Vlaardingen, The Netherlands

Erik van der Linden

Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen, The Netherlands

Preferred Abstract (Original):

Mixtures of γ-oryzanol and β-sitosterol were used to structure different oils (decane, limonene, sunflower oil, castor oil, and eugenol). The γ-oryzanol and β-sitosterol mixtures self-assemble into double-walled hollow tubules (∼10 nm in diameter) in the oil phase, which aggregate to form a network resulting in firm organogels. The self-assembly of the sterol molecules into tubules was studied using light scattering and rheology. By using different oils, the influence of the polarity of the oil on the self-assembly was studied. The effects of temperature and structurant concentration on the tubuler formation process were determined and the thermodynamic theory of self-assembly was applied to calculate the change in Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) resulting from the aggregation of the structurants was determined. The self-assembly was found to be enthalpy-driven as characterized by a negative ΔH0 and ΔS0. A decreasing polarity of the oil promotes the self-assembly leading to formation of tubules at higher temperatures and lower structurant concentrations.

The Influence of Concentration and Temperature on the Formation of γ-Oryzanol + β-Sitosterol Tubules in Edible Oil Organogels

Thu, 2013-02-14 14:44 — Hassan Ismaiel Sawalha (Manasra)

Journal Title, Volume, Page:

Food Biophysics, 6(1): p. 20–25

Year of Publication:

2011

Link:

http://link.springer.com/article/10.1007/s11483-010-9169-9/fulltext.html

Authors:

Hassan Sawalha

Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands

Current Affiliation:

Chemical Engineering Department, An-Najah National University, Nablus, Palestine

[email protected]

Paul Venema

Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands

Arjen Bot

Unilever Research and Development Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands

Eckhard Flöter

Unilever Research and Development Vlaardingen, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands

Erik van der Linden

Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands

Preferred Abstract (Original):

The gelation process of mixtures of γ-oryzanol and sitosterol structurants in sunflower oil was studied using light scattering, rheology, and micro-scanning calorimetry (Micro-DSC). The relation between temperature and the critical aggregation concentration (CAC) of tubule formation of γ-oryzanol and sitosterol was determined using these techniques. The temperature dependence of the CAC was used to estimate the binding energy and enthalpic and entropic contribution to the tubular formation process. The binding energy calculated at the corresponding temperatures and CACs were relatively low, in order of 2 RT (4.5 kJ mol−1), which is in accord with the reversibility of the tubular formation process. The formation of the tubules was associated with negative (exothermic) enthalpy change (ΔH 0 ) compared with positive entropy term (−T ΔS 0 >0), indicating that the aggregation into tubules is an enthalpy-driven process. The oryzanol–sitosterol ratio affected the aggregation process; solutions with ratio of (60 oryzanol–40 sitosterol) started aggregation at higher temperature compared with other ratios.