Structural, functional, rheological, and biological properties of the swim bladder collagen extracted from grass carp (Ctenopharyngodon idella)

The objective of this study was to develop an aquatic collagen with high thermal stability as a possible alternative to terrestrial sources. Swim bladder collagen (SBC) was extracted from grass carp with high yield of 39.2% (db), and characterized as type I collagen. X-ray diffraction indicated that SBC maintains a native triple helical collagen structure. Secondary structure analysis revealed that SBC consists of 41.93% α-helices, 45.31% β-sheets, 12.76% β-turns, and 0% random coils. Proteins from SBC exhibited foaming and emulsifying superiority to proteins from terrestrial sources, such as chicken feet collagen. The thermal denaturation temperature of SBC (34.3 °C) is similar to porcine skin collagen. Dynamic frequency sweep tests showed that elasticity plays a dominant role in the SBC solution system as the concentration increases. The SBC solution system shows viscous behavior when the temperature is below Td. In addition, the steady shear tests showed that all of the SBC solutions exhibited pseudoplasticity with shear-thinning behavior. SBC could provide a suitable environment for MC3T3-E1 cell growth and maintain normal cellular morphology. Overall, the results indicated that SBC might has potential for further applications in food, cosmetics and biomedical fields.