Comparative study on the amphiphilicity, emulsifying and foaming properties of saponins extracted from Furcraea foetida

A sustainable surfactant was obtained as a by-product of waste from the production of fibers from Furcraea foetida (FF). The extraction process is described and the chemical constituents (flavonoids, saponins and others) in the hemp of Mauritius in Madagascar were determined using ultra-performance liquid chromatography coupled to high resolution hybrid mass spectrometer. The hypothesis of surface-active behavior of this crude mixture was corroborated by surface tension measurements and these results were compared with 2 commercial Quillaja saponaria (QS) samples: S0019 (TCI) and Q-Naturale 200 V. The critical micellar concentration of the FF saponins is 0.025 wt%. The hydrophilicity-lipophilicity radius was determined by the PIT-slope method and all saponins are more hydrophilic than the C10E4, the polyethoxylated reference surfactant. The hydrophilicity decreasing order is as follows: Q-Naturale 200 V > FF> S0019. Oil in water (O/W) emulsions were formulated with isopropyl myristate as oil and their size distribution and stability during 7 days are equivalents for the three saponins. There is no coalescence, and creaming phenomena can be reduced increasing the oil fraction. Nanoemulsions were obtained with FF using ultrasounds and reducing the oil content. Foaming properties were also studied and the stability of foams is similar between the 3 saponins (higher than the foam formulated with sodium laureth sulfate). These findings show that FF is a new source of saponins that can be used as promising emulsifier and foam agent with properties equivalent to those quantified for available commercial saponins and equal or better than typical benchmark surfactants as Tween 40 (emulsifier) or sodium laureth sulfate (foaming agent).