Small-angle neutron scattering study on self-assembled sitosterol-oryzanol tubules

The firmness of oil-continuous food products, such as margarine or butter, is based on a network of small crystallites of triglycerides. Few alternative routes to structure food grade oils are known that are not explained in essence by fatty acid crystallisation behaviour. One exception is the mixture of ¿-oryzanol with ß-sitosterol, which forms helical ribbons appearing as tubules through self-assembly. Small-angle neutron scattering was applied to organogels and emulsion gels based on these plant sterol systems, to investigate the structure of the sitosterol + oryzanol tubules in more detail. Special attention was given to contrast variation studies by using various solvents in which the sterol mixture had previously been shown to form tubules. The present study shows that the wall of the tubule can be considered to consist of two layers, of which the outer layer is composed of the ferulic acid moieties in the oryzanol. Further refinements in the tubule model are desirable to move the current semi-quantitative analysis to a quantitative one