Abstract:

In this study, the kinetic behavior and influential factors of self-assembly, fiber morphology and thermal stability
of pepsin soluble collagen from grass carp skin were explored. The turbidity and self-assembly degree indicated that grass
carp skin collagen had self-assembling ability although it was influenced by collagen concentration, pH, ionic strength and
temperature. Under the conditions of 7–8, 3–5 mg/mL, 25–30 ℃ and 0–200 mmol/L for pH, collagen concentration, culture
temperature and NaCl concentration, respectively the self-assembling process progressed faster and finally reached a higher
level. The kinetic analysis suggested that the whole assembly reaction could be divided into nucleating, fibrillogenesis and
plate phases at higher ionic strength and lower temperature, but divided into rapid assembly, slow assembly, and plate phases
when the assembling conditions were changed to lower ionic strength and higher temperature. Morphological observations
indicated that grass carp skin collagen could be self-assembled into fibrils with characteristic D-periodicity in vitro, but the
length of D-periodicity (64.6 nm) was smaller than that of the mammalian counterpart (approximately 67 nm). The results of
DSC analysis showed that the thermal stability of grass carp skin collagen was obviously improved after self-assembly.

Key words: fresh water fish, collagen, self-assembly, kinetics