The effects of amino acids on the gel properties of potassium iota carrageenan

The effects of positive and neutral charged amino acids (Arginine (Arg) and Glutamine (Gln)) on the gel properties and microstructure of potassium iota Carrageenan (KIC) were investigated. The findings suggested that the gel melting temperature (T-g) of KIC gels increased from 36 degrees C to 43 degrees C with the Gln concentration increasing, and the elastic modulus (G') increased as well. However, with the increase Arg concentration, T-g and G' of gels increased gradually and then decreased, and the maximum T-g (46 degrees C) and G' were obtained at concentrations of 0.05% Arg. LF-NMR results showed that the addition of Gln decreased the position of T-23, indicating a negative effect of Gln on the water holding capacity and water mobility of KIC gels, while the addition of Arg increased the position of T-23, showing the opposite effect. Compared to the pure KIC and Gln-KIC (GKIC), Arg-KIC (AKIC) showed a more regular network structure and a stronger water holding capacity. In addition, few chemical bonds were formed between amino acid and KIC. It is electrostatic attraction between KIC and Arg and the crowding of Gln that contributed to better gel properties. Taken together, our results provide insights for the further application of GKIC or AKIC gels in food and medical applications.