Tea saponins: effective natural surfactants beneficial for soil remediation, from preparation to application

Abstract

This review details the industrial extraction and purification processes of tea saponins from Camellia plants and clarifies their mechanisms for soil remediation.

Development of a Rapid and Simple Method for Preparing Tea-Leaf Saponins and Investigation on Their Surface Tension Differences Compared with Tea-Seed Saponins

“…Currently, seed meals of C. oleifera , the by-product from Camellia oil (tea-seed oil) extractions, are the principal source of tea saponins, specifically tea-seed saponins [ 4 , 5 , 14 ]. There is less research on the extraction of saponins from tea leaves, both the precipitation and the application, although researchers have summed up current literature on tea saponins (taking tea-seed saponins and tea-leaf saponins as a whole) from preparations to applications as natural surfactants [ 15 ]. Follow-up studies focused simply on tea-leaf saponin are required.…”

“…Water extraction [ 26 , 27 ], organic solvent extraction [ 4 , 28 , 29 , 30 ], mixed solvent extraction [ 31 ], microwave-assisted extraction [ 5 , 32 , 33 ], ultrasonic-assisted extraction [ 34 , 35 , 36 ], supercritical extraction [ 37 ], aqueous enzymatic [ 38 , 39 , 40 ] and fermentation [ 41 ] are methods utilized for extracting saponins from tea-seed saponins. Although alcohol extraction, especially ethanol extraction, appears to bear a higher yield in tea-seed extractions [ 15 ], due to the difference of extraction objects, for instance, seed meals of C. oleifera for tea-seed saponins and leaves of C. sinensis for tea-leaf saponins, water extraction might be a better choice for extracting tea-leaf saponins, as inferred and discussed by Yu. and He.…”

“…and He. [ 15 , 42 ]. To improve the performance of water extraction, ultrasound, which has a better assistant performance compared with microwave and light-wave [ 15 ], was applied as an auxiliary method in this research.…”

“…[ 15 , 42 ]. To improve the performance of water extraction, ultrasound, which has a better assistant performance compared with microwave and light-wave [ 15 ], was applied as an auxiliary method in this research. As for precipitation, the easiest and most convenient refined purification method, acetone precipitation, was selected for refining crude tea saponins from aspects of experiments’ operability, instrument and reagent’s price as well as purities of tea saponins.…”

Compounded chelating agent derived from fruit residue extracts effectively enhances Cd phytoextraction by Sedum alfredii

“…In a study conducted by Liu et al (2017), who have shown that the application of tea saponin also caused increases in soil enzyme activities and improvement of plant growth. Similarly, recent studies demonstrated that tea saponin was able to facilitate the removal of heavy metals (e.g., Cd, Zn, Cu) from metal-contaminated soils as well (Cay, 2016;Yu and He, 2018). In light of these findings, tea saponin might be a promising amendment that can aid in heavy metals phytoextraction (Cay, 2016).…”