Structuring Niger Seed Oil with Beeswax: Physicochemical, Structural, and Oxidative Stability Insights into Oleogel Formation

Substituting saturated and trans fats with healthier lipid systems is an urgent requirement in food formulation, and oleogelation is a viable approach. This work utilised niger seed oil, a novel edible oil abundant in unsaturated fatty acids, which was structured using beeswax as an oleogelator. Oleogels were prepared using a magnetic stirrer at 400 rpm and 90 °C for 20 minutes until the beeswax was fully dissolved. The critical gelation concentration of beeswax was found at 3%, leading to the selection of formulations with 4% (BW4), 7% (BW7), and 10% (BW10) beeswax for physicochemical characterisation.

Physicochemical properties were strongly influenced by beeswax addition. The color parameters shifted with increasing wax concentration, with lightness (L*) increasing from 36.88 to 48.98, red to green (a*) changing from −2.03 to −2.52, and yellow to blue (b*) increasing from 7.52 to 15.98. Oil binding capacity improved from 93.22% to 98.92%, while hardness rose from 1.4 N (BW4) to 3.4 N (BW10). X-ray diffraction revealed enhanced crystallinity with higher wax levels, while FTIR spectra confirmed that the oleogel retained the chemical identity of the oil. All oleogels exhibited shear thinning behaviour and were best fitted to the Power law model (R² = 0.95-0.99). The addition of waxes resulted in an increased apparent viscosity of the oleogels. Increased wax levels enhanced the storage and loss modulus, making the gels rigid. It was observed that at higher wax concentrations, creep compliance decreased and recovery rates were enhanced. Oxidative stability tests indicated that although peroxide and p-anisidine values increased during 30 days of storage, higher wax concentration reduced oxidation compared to lower concentrations.

Overall, beeswax-structured oleogels successfully enhanced the functional and oxidative stability of niger seed oil, demonstrating their potential as sustainable fat alternatives in food applications.