Pomegranate seed oil (PSO) contains considerable amounts of polyunsaturated fatty acids including conjugated linolenic acid (CLnA) isomers, like punicic acid (18:3–9cis, 11trans, 13cis), with remarkable therapeutic and preventive effects on human health. Unfortunately, different issues have to be overcome in the attempt to enrich food with PSO. A major issue is to find a way to delivery it in a system that allows its incorporation in the food matrix as well as protecting it from oxidation. The gelation of oil by using a three-dimensional gel network of small self-assembled molecules could be a pursuable strategy.
The aim of the present research was to develop PSO organogels by using beeswaxes and waxes extracted from propolis. It should be noted that propolis waxes was proposed in this study as new natural organogalator. After the chemical characterization of propolis and bees waxes, PSO was mixed with the two type of waxes and their mixture (1:1) at different concentration (5, 10 and 15% w/w). Organogels were characterized by using different techniques, including polarized light microscopy, synchrotron X-ray diffraction, rheology, and mechanical properties. Finally, peroxide value changes during storage at 20 °C was measured as index of oxidation.
Results highlighted that propolis waxes could form organogel thanks to the presence of a crystal network made of needlelike β′-form crystals. Propolis wax organogel had larger crystals with less organized network in comparing to that formed by beeswaxes. The combined use of propolis wax and beeswax improved rheological and mechanical properties of propolis wax organogel. Regarding oxidative stability, the presence of propolis wax at 15% (w/w) delayed pomegranate seed oil oxidation probably due to the presence of antioxidants. In accordance with these findings, both propolis and bees waxes can be considered as good gelators of PSO. Depending on intended food application, the final structure of the organogel can be tailored by selecting the organogelator and its concentration.
