Effect of salts on the gelatinization and rheological properties of sago starch

The effects of various salts on the gelatinization and rheological properties of sage starch have been studied using differential scanning calorimetry, small deformation oscillation, and large deformation techniques. The presence of salts affected the gelatinization peak temperature, T-p, gelatinization enthalpy, Delta H, swelling properties, storage modulus, G', gel strength, GS, and gelation rate constants, k, depending on the type of salt and the concentration. Their influence followed the Hofmeister series, and the effect of anions was more pronounced than that of cations. Sulfate ions increased T-p, G', GS, and k and reduced the swelling properties, whereas iodide and thiocyanate ions reduced T-p, G', GS, and k but increased the swelling properties. For all of the salts studied except for Na2SO4, T-p increased to a maximum and then decreased again at higher salt concentrations while Delta H reduced with concentration. In the presence of MgCl2, CaCl2, and LiCl complex behavior was observed such that at similar to 3.5 M MgCl2 and CaCl2 and 8 M LiCl the starch samples were gelatinized at room temperature, whereas at much higher concentration T-p increased again and the transition became exothermic.