LAUSR

Abstract The effect of various inorganic salts on the physical gelation behavior of the gelatin solutions was investigated by Fourier transform infrared (FTIR) spectrometer, polarimeter, rheometer, X-ray diffraction and differential scanning calorimetry. It was found that strongly hydrated anions, such as SO42− and H2PO4−, facilitated the gelation of the biopolymer solutions, evidenced by the increases of the length and content of triple helices. On the contrary, weak hydrated anions like Cl− and SCN− hindered the coil-helix transition of gelatin. Additionally, the gelling temperature ( T g e l ) of protein was directly correlated to the hydration entropy of anions, demonstrating that the elevation of T g e l was attributed to the strong hydration effect of kosmotropic anions. On the other hand, chaotropic anions lowered T g e l , due to the direct interactions of weak hydrated anions with polypeptide backbones which were confirmed by the FTIR results. These observations indicate that the gel structure can be modulated by Hofmeister salts.