Enhanced hydrophobic interaction between fish (Cyprinus carpio L.) scale gelatin and curcumin: Mechanism study

To enhance the solubility of hydrophobic nutrients, the hydrophobicity of fish scale gelatin hydrolysate (FSGH) was increased with moderate acid or alkali hydrolysis. Acid-induced FSG hydrolysate (AcFSGH) at 3 h showed a superior curcumin loading efficiency (18.30 ± 0.38 μg/mL) among all FSGHs. Compared with FSG, the proportion of hydrophobic amino acids (from 41.1% to 46.4%) and the hydrophobic interaction (from 12.72 to 20.10 mg/mL) was significantly increased in the AcFSGH. Meanwhile, the transformation of the α-helix (from 12.8% to 4.9%) to the β-sheet (from 29.0% to 42.8%) was also observed in the AcFSGH. Based on the observation in the molecular weight and morphological analysis, AcFSGH acquired the best hydrophobic interaction with curcumin, presumably due to the formation of the flexible structure of the linear hydrolyzates. The above results call for an investigation of the role of FSG hydrolysate in the synthesis of nanoparticles loaded with bioactive lipophilic compounds.