Self-Nanoemulsification of Unsaponifiable Fraction From Palm Fatty Acid Distillate

Unsaponifiable fractions (USF) from palm oil fatty acid distillate (PFAD) contained multicomponent bioactive compounds, including tocopherol, tocotrienols, phytosterols, and squalene. USF is potentially applied as a food supplement for antioxidant, anti-inflammatory, anticholesterol, and other health benefits for some diseases and metabolic disorders. Besides, this material is suitable as a fortificant for food formulation to have palm bioactive containing products as functional foods. However, the problem in using USF is its water immiscibility. This study aims to overcome the problem of low water solubility of USF from PFAD. The self-nanoemulsification method will be applied to solve the problem by using two types of surfactants (Tween 80 and sodium stearoyl lactilate/SSL) at 5%, 10%, and 15% based on the oil phase. The results showed that the nanoemulsion had an average diameter of 55–162 nm, and the smallest particle size was produced by the nanoemulsion with 15% Tween 80. The nanoemulsion with 15% SSL had the best stability with an emulsion stability index (ESI) value of 452.79 ± 21.37 min and had the largest interfacial area (IA) of 6.99 ± 0.29 m²/mL. Bioactive compounds from USF were found in the nanoemulsion and their levels were influenced by the type and concentration of surfactants. The presence of low levels of β-carotene resulted in a pale yellow color in the nanoemulsion. The bioactive compounds of the nanoemulsion were dominated by tocotrienols and phytosterols as the main phytochemicals in USF. The different molecular structures and behaviors at the oil–water interface of Tween 80 and SSL affected the characteristics of the nanoemulsion. SSL performed better in producing better emulsifying activity and stability, as well as a larger interfacial area. This surfactant was also able to retain tocotrienols and β-carotene better. Meanwhile, phytosterols are more suitable in nanoemulsions stabilized with Tween 80. Differences in the features of SSL and Tween 80, including critical micelle concentration, affect their ability to produce better nanoemulsion characteristics as their concentrations increase.