Characterization of Fish Gelatin at Nanoscale Using Atomic Force Microscopy

Abstract

Atomic force microscopy (AFM) was used as a meaningful tool to characterize the nanostructure of gelatin from catfish (Ictalurus punctatus) skin. The gelatins extracted with pretreatments including acid pretreatment, alkaline pretreatment, and alkaline followed by acid pretreatment (optimized extraction conditions). The resulting gelatins were imaged using AFM and their nanostructure was studied. The AFM images showed that gelatin extracted with acid pretreatment had a coacervate structure while with alkaline pretreatment there were separate aggregates. Spherical aggregates and annular pores were observed in AFM images of gelatin with the optimized extraction conditions. AFM imaging of gelatin with a relative high concentration (0.5%) was successfully done and the results help researchers to understand gelatin structures at the nanoscale.

Effects of Pretreatment on Properties of Gelatin from Perch (Lates Niloticus) Skin

“…[5] Acid and alkaline pretreatment as well as extraction conditions affect both composition and distribution of hydrophobic amino acid of fish gelatin, and thereby influenced their physical properties. [6,7] Generally, mild acid pretreatment is used for gelatin production due to low concentration of intra-and inter-chain non-reducible crosslink in fish collagen and this process is sufficient to achieve adequate swelling and disruption of the non-covalent intra-and inter-molecular bonds. [8,9] Alkali, particularly lime, pretreatment of fish skins may reduce protein molecular size through slight hydrolysis of the polar regions and this facilitates lyotropic hydration or swelling of collagen protein by organic acids.…”

Physicochemical and Rheological Properties of White-Cheek Shark (Carcharhinus dussumieri) Skin Gelatin

“…For perch skin gelatin, a fine gelatin surface had been observed when alkali and acid were used for pretreatment as compared to alkali pretreatment alone [28]. Spherical structures were also found in the AFM images of alkaline-acid pretreated catfish gelatin [29]. However, Yang and Wang [26] showed that in low concentrations to be correlated inversely to the gelatin molecular weight distribution [27].…”

Advances in research on structural characterisation of agricultural products using atomic force microscopy

“…Gelatin has a wide range of applications in the food, pharmaceutical and photographic industries, so understanding and then improving the physical properties of gelatin is important for increasing its utilisation. Yang and co‐workers26–29 have carried out a series of studies on the gelatin from catfish ( Ictalurus punctatus ) skin. Catfish gelatin molecules with annular pores and spherical aggregates were seen for the first time by them.…”