Reversible regulation of gelatinization of potato starch with poly(ε-lysine) and amino acids

Poly(F-lysine) (PL), lysine (Lys), monosodium glutamate (GluNa), glycine (Gly), alanine (Ala), and leucine (Leu) were used to regulate the characteristic gelatinization behavior of potato starch. As determined by differential scanning calorimetry, PL, Lys, and GluNa with positive or negative net charge elevated the gelatinization temperature with increasing amount added as compared with the small effect of Gly, Ala, and Leu with zero net charge. The peak viscosity evaluated by a Rapid Viscoanalyser was markedly decreased by adding PL, Lys, and GluNa, whereas Gly and Ala had no effect on the peak viscosity. The swelling was also decreased by added PL, Lys, and GluNa, whereas it was unchanged by added Gly, Ala, and Leu. Potato starch immersed in PL or amino acid solution released most of the retained PL and amino acids by the subsequent washing with water. The increased gelatinization temperature of the PL-treated potato starch returned to the original value by washing with water. It is thus considered that the regulatory effects of PL and amino acids on the gelatinization behavior of potato starch were substantially reversible.