Moringa oleifera seed protein isolate preparation: influence of hofmeister ions and optimization by rsm.

Protein energy malnutrition existence necessitated extensive research into
unexploited protein sources. Moringa oleifera is a highly valued vegetable plant and
its seed meal contains ~52% protein. However, presence of multiple isoelectic point
restricts protein isolate preparation by the conventional method. The objective of the
present study is to understand influence of Hofmeister ions on M. oleifera seed
protein isolate preparation and optimize protein extraction with selected salt using
response surface methodology (RSM). RSM was employed to study the effect of
solvent to flour ratio, salt concentration and temperature on protein extraction
efficiency (PEE). Results showed that PEE with cations followed a direct Hofmeister
series (Na+ ~ K+ < Mg2+ < Ca2+) while with anions followed a reverse Hofmeister
series except for Cl- and Br− ions which advanced their position (SO4
2− > Cl− > Br− >
HPO4
2− ~ CH3COO− > I− > SCN−). Among the ten different salts examined, Na2SO4
(69.9%), KCl (66.2%), NaCl (65.4%), and NaBr (63.5%) displayed not only better
PEE but also resulted in higher PMM yield (~52% true protein) with a purity >90%.
Although, anyone of these salts could be chosen, NaCl is preferred considering its
wider acceptance in various applications.