Extraction and purification of saponins from Sapindus mukorossi
Saponins extracted from Sapindus mukorossi are natural nonionic surfactants with various biological activities and strong surface activities, which can be widely used in biomedicine and the daily cleaning chemical industry. In this paper, Sapindus pericarp was used as the raw material for the extraction of saponins. Effects of major extraction variables, including solvents, extraction methods, material-to-liquid ratios, and extraction time were investigated. A yield of 30.48% and purity of 61.38% were obtained by using water extraction for 4 h with a material-to-liquid ratio of 1 : 6. Fermentation was used to purify the saponins, and a high sugar resistant yeast performed better with an optimal amount of 5%. The saponins concentration slightly decreased from 38.86 g L−1 to 37.72 g L−1 after fermentation, and the purity of the saponins increased to 78.97%. Structure and performance tests of homemade saponins were also carried out. The structure of Sapindus saponins was found to be similar to that of mukurozi-saponin using FTIR and HPLC, and the foam half-life of homemade saponins was 25.82% longer than that of unfermented saponins. On comparing four chemical surfactants, the foam half-life of saponins after fermentation was found to be much longer. These results provide useful information for the development of industrial purification and application of Sapindus saponins.