Zein–curcumin composite colloidal particles were synthesized using an antisolvent precipitation method. The average particle size could be controlled down to 100–150 nm, depending on the solvent system and the ratio of zein and curcumin used in the synthesis. In all cases, spherical particles were obtained, as confirmed by transmission electron microscopy. Depending on the preparation conditions, curcumin load and encapsulation efficiency varied from 1.6 to 4.1% and 71.1 to 86.8%, respectively. Solid state characterization by differential scanning calorimetry and X-ray diffraction indicated the amorphous nature of entrapped curcumin. An UV irradiation study confirmed enhanced photostability of curcumin due to the entrapment of curcumin in the biopolymeric matrix. The particles were also found to have good colloidal stability at a broad range of physiologically relevant pH (1.2, 4.5, 6.7 and 7.4) and in simulated gastro-intestinal conditions. Results from an in vitro mucoadhesion study showed retention of more than 60% curcumin for 150 minutes. The mucoadhesion property was further confirmed from a mucin association study carried out on Caco-2 cells.

In recent years, research dealing with edible oil structuring has received considerable interest from scientific community working in the area of food formulation. Much of this interest is linked to the possibility of using structured oil in development of newer product formats with improved nutritional profile (trans fat-free, low in saturated fats and high in mono and/or poly unsaturated fatty acids). In addition to the obvious industrial need of finding the alternative formulation approach, the interesting properties of structured systems (particularly, oleogels) also makes them a fascinating subject for fundamental studies. In this paper, we attempt to give a comprehensive and concise overview of the field of oil structuring with special emphasis on the updates from recent years. Specifically, several categories of food-grade oleogelators and their potential food applications are summarized with typical examples along with a discussion on the general principles and unresolved challenges related to this emerging area.