Optimization of Microwave-Assisted Extraction of Tea Saponin and Its Application on Cleaning of Historic Silks

Microwave-assisted extraction (MAE) was utilized to extract tea saponin from oil-tea camellia seed cake. The factors influencing the extraction efficiency were studied, including the effects of microwave power, irradiation duration, temperature, ratio of solvent to material and aqueous ethanol concentration. By systematic orthogonal experiments, the optimal extraction technology was determined. Compared with a conventional extraction method, MAE shows great advantages with the extraction time reduced from 6 h to 4 min, 50 % organic solvent saved and about 14 % extraction yield enhanced. Fourier transform infrared spectroscopy testing and high performance liquid chromatography analysis proved that the extracted resultants were tea saponin with similar compounds as a standard tea saponin. The extracted tea saponin was applied on the cleaning of historic silks and showed good removal effect on the stains. This work provides useful information for fully use of oil-tea camellia seed cake and new applications of tea saponin at the protection of historic textiles.