Improvement of extraction method of coagulation active components from Moringa oleifera seed

A new method for the extraction of the active coagulation component from Moringa oleifera seeds was developed and compared with the ordinary water extraction method (MOC–DW). In the new method, 1.0 mol l−1 solution of sodium chloride (MOC–SC) and other salts were used for extraction of the active coagulation component. Batch coagulation experiments were conducted using 500 ml of low turbid water (50 NTU). Coagulation efficiencies were evaluated based on the dosage required to remove kaolinite turbidity in water. MOC–SC showed better coagulation activity with dosages 7.4 times lower than that using MOC–DW for the removal of kaolinite turbidity. MOC–SC could effectively coagulate more than 95% of the 50 NTU initial kaolin turbidity using only 4 ml l−1, while 32 ml l−1 of MOC–DW could only remove about 78% of the same kaolin turbidity. The improvement of coagulation efficiency by NaCl is apparently due to the salting-in mechanism in proteins wherein a salt increases protein–protein dissociations, leading to increasing protein solubility as the salt ionic strength increases. There was no difference in the coagulation efficiency observed for extracts using any of four 1:1 salts (NaCl, KNO3, KCl and NaNO3) in our study. Purification and isolation of the active component confirmed that the active component of MOC–SC was mainly protein.