Effects of L-lysine and L-arginine on the structure and gel properties of konjac glucomannan

To explore greener modifier of konjac glucomannan, a new type of thermal irreversible gel using konjac glucomannan (KGM) and basic amino acids (l-lysine, and l-arginine) was prepared in the present study. The effects of different concentrations (1%, 2%, 3%, 4%, and 5%) of these two basic amino acids on the structure and properties of KGM hydrogels were mainly studied. The results showed that there was a better texture characteristic of composite gel as the concentration of amino acids was above 4%. Besides, with the increase in amino acid concentrations, the pore size of composite gel was denser and the syneresis of composite gel was more obvious, respectively. The rheological results indicated that the storage modulus (G′) was influenced by the concentration of amino acids and temperature. It was found that the two basic amino acids removed the acetyl group of KGM molecule and changed the original crystalline domain of KGM as evidenced by FT-IR and X-ray diffraction (XRD) analysis. Furthermore, compared to l-lysine, l-arginine could exert a greater effect on the KGM gel. In conclusion, the two basic amino acids (l-lysine, and l-arginine) could remarkedly improve the structure and properties of natural KGM and could be used as modifiers of the KGM hydrosol.