Biosurfactant saponin from leaf extract of Morinda citrifolia L. as emulsifier to improve β-carotene solubility in microemulsion

Leaf extract of Morinda citrofilia L. contains several types of secondary metabolites; one of them is biosurfactant saponin which can be used as emulsifier in microemulsion formation. Saponin extraction was performed with maceration technique, identified by phytochemical test and characterized using FTIR and UV-Vis spectrophotometer. β-carotene is a natural colorant which frequently used in beverages but it is vulnerable to temperatures and lights. Palm oil was used as oil phase. β-carotene solubilization in microemulsion increases the stability. Microemulsion formation was performed by varying the surfactant, co-surfactant and oil phase. Microemulsion stability was observed using turbidimeter, microscope, and particle size analyzer (PSA). β-carotene solubility and stability in microemulsion system were observed using UV-Vis spectrophotometer. Microemulsion particle size was confirmed at 9.65 nm. The stabilized oil in water microemulsion was obtained with ratio of surfactant and co-surfactant (Sm) at 8:2, and ratio of Sm and oil at 14:1. β-carotene optimum solubility in microemulsion system was obtained at 2.00 mg/mL.