Lutein extraction using nanotechnology (microemulsion): effect of surfactant, co-surfactant and ultrasound pretreatment

In the present study, the ability of microemulsion technique (MET), as an environmentally friendly green nano-technology and potential alternative technique for the organic solvent extraction methods on lutein extraction from marigold petals, a major plant source containing 15.83mg/g (dry weight), was assessed. For this purpose, the capability of eight surfactants (Saponin, Lecithin, Rhamnolipid, Sucrose Monopalmitate, Span 20, Tween 20, Tween 80 and Sodium Dodecyl Sulfate) in combination with four cosurfactants (Ethanol, 1-poropanol, Glycerol and Propylene Glycol) on extraction yield was investigated. The experimental results showed without co-surfactants and over SOR range of 200:1 to 2000:1 the extraction yield was 5.11–13.22% (in comparison with acetone). However, by using various cosurfactants, the extraction efficiency was significantly (p< 0.05) increased. The highest yield was obtained using Tween 80: 1-propanol at SCR of 2:1 (39.41%). The next set of this study attempted to investigate pretreatment effects (i.e., ultrasonication) on enhancement of extraction efficiency. For this purpose, the natural microemulsion composed of SMP:1-propanol (surfactant: co-surfactant ratio, SCR 1:5) was exposed to sonication for various times (30, 60, 90 and 120 seconds) at different amplitudes (25, 50, 75 and 100%). The results showed that by rising the sonication time and amplitude, the extraction efficiency was outstandingly (~200%) increased (e.g., from 25.52% to 71.19% when sonicated for 120 seconds at max amplitude). These findings revealed the outstanding success of sonication pretreatment as well as importance of type and precise composition of microemulsion ingredients (surfactant, co-surfactant, water and oil phase ratios) on its extraction capability and yield.