From medicinal and food homologous biomass to total glycosides in Rehmannia glutinosa leaves extracts: Microemulsion-based negative pressure cavitation-assisted extraction

Food-grade and sustainable peppermint oil microemulsion was prepared through gradual screening of components for extraction of total glycosides in Rehmannia glutinosa leaves. The optimal microemulsion was: 6:3:1:25.71 (Tween 80: ethanol: peppermint oil: 0.02 mol/L KCl, w-w:w:w). 1 mol/L KCl solution was used for back-extraction to achieve sustainability of microemulsion. Microemulsion could be used at least 4 cycles. To optimize sustainability of microemulsion, negative pressure cavitation-assisted extraction technology was used as an auxiliary method. Which also makes extraction more suitable for large-scale industrial production. Consequently, microemulsion-based negative pressure cavitation-assisted extraction technology was developed. The optimal conditions for technology were as follows: 5.5 of pH, 37 min of time, and 10 mL/g of liquid-solid ratio. The yield of total glycosides was 45.13 mg/g. This newly established technology, as a cleaner alternative approach, can therefore be used to extract total glycosides from Rehmannia glutinosa leaves.