Effects of Acidic/Alkali Pretreatment on Physicochemical Properties and Gelation Characteristics of Bone Gelatin from American Eel (Anguilla rostrata)

Fish bone gelatins were prepared from Anguilla rostrata by acidic or alkali pretreatment combined with hot water extraction. The physicochemical properties and gel properties of fish bone gelatins were investigated via the yield determination, gel strength measurement, SDS-PAGE analysis, ultraviolet full-wavelength scanning, infrared spectrum scanning, dynamic rheology measurement and scanning electron microscopy. As results, the yields of acid pretreated gelatin (AG60) and alkaline pretreated gelatin (BG60) were 13.6% and 6.88%, with the corresponding gel strengths of 101.95 g and 78.74 g, respectively. The hydroxyproline contents of AG60 and BG60 were 3.2 g/100 g and 2.7 g/100 g. Both gelatins were mainly consisted of β and α₁, α₂ chains, the contents of α₁ and α₂ chains in AG60 was significantly higher than those in BG60. Both AG60 and BG60 possessed the characteristic absorption peak of gelatin without any absorption peaks for other proteins. The AG60 possessed higher gelling temperature and melting temperature, as well as a shorter gelling time. Scanning electron microscopy analysis showed that AG60 showed a more dense and uniform gel network structure as compared with BG60. Present study suggested that the eel bone gelatin prepared by acidic pretreatment had better gel properties than that of gelatin prepared by alkali pretreatment.