| Collagen is an important structural protein mainly found in animal skin,muscle bonds,ligaments and other connective tissues.Glue has the advantages of good biodegradability,hemostasis,and low immunogenicity,and has gradually become a new industry.The annual market demand for collagen is as high as 200,000 tons,and the sales of collagen products reach 200 to 1 billion US dollars,which has huge development potential and market prospects.In recent years,the outbreak of infectious diseases such as mad cow disease,avian flu,swine fever,etc.has caused people to worry about the use of land-derived collagen,and marine-derived collagen has become a research hotspot of many scholars in recent years.In this paper,the navodon septentrionalis fish skin was used as the research object.The collagen was prepared by the integrated technology of acid extraction and salting-out and dialysis,the structure was identified,and its functional properties and rheological properties were analyzed.On this basis,the effects of p H and temperature on the microstructure,functional properties and rheological properties of the collagen of puffer fish skin were explored,and the law of changes induced by p H and temperature was explained.The main experimental results are as follows:1)Using horse-face puffer fish skin as the research object,prepare horse-face puffer fish skin collagen.The experimental results show that the collagen yield of horse-face puffer fish skin is 14.8%(wet weight),which is better than deep-water bream skin collagen,tilapia skin collagen and Spanish mackerel skin collagen.The results of SDS-PAGE electrophoresis experiments showed that the collagen of horse face puffer fish skin is a typical type I collagen.The results of ultraviolet spectroscopy,infrared spectroscopy,circular dichroism and X-ray diffraction experiments show that the prepared collagen maintains the unique triple helix structure of collagen without denaturation.The results of water contact angle experiments show that the water contact angle of pufferfish skin collagen is(103.77±0.58)°,which is highly hydrophobic.The emulsification of collagen is 234.09 m~2/g,and the emulsification stability is 50.67 min.The foamability of collagen is 17.8%,and the foam stability is 55.06%.The water holding capacity of collagen is 22.56±2.77g/g,which is better than chicken feet collagen(1.90±0.10 g/g),pig skin collagen(0.21±0.03 g/g),red snapper gelatin(1.98±0.03 g/g)Grouper bone gelatin(2.48±0.04 g/g).In addition,the oil absorption of collagen is13.69±0.05 g/g,which is better than chicken feet collagen(5.30±0.3 g/g)and papaya seed protein(10.77±0.33 g/g).The experimental results of the rheological properties of collagen show that the elastic modulus(G'),viscous modulus(G"),and complex viscosity(?*)of the collagen of puffer fish skin increase with the increase of the concentration.Significant increase in concentration,the G'and G"of the collagen solution increased by one to three orders of magnitude,indicating that the concentration has a significant effect on the G',G"of the collagen solution.Therefore,the puffer fish skin is a kind of collagen preparation.It is a good material,horse-face puffer fish skin collagen can be used as a substitute for land-derived collagen,applied to food,cosmetics,biomedical engineering and other fields,and then realize the high-value utilization of low-value resources.2)Investigate the effects of different p H on the structure,function and rheological properties of the collagen of puffer fish skin.The Zeta potential experiment results of collagen showed that the isoelectric point of the collagen from the puffer fish skin was 7.83.The experimental results of the contact angle of collagen showed that the contact angle of pufferfish skin collagen reached the maximum(83.12±3.69)°at p H 7.83.The experimental results of collagen functional properties showed that the emulsification and emulsification stability,foaming and foam stability showed a trend of first decreasing and then increasing with the increase of p H,and all reached the lowest value at p H 7.83.The results of Fourier Infrared Spectroscopy showed that with the increase of p H,the amide I band of puffer fish skin collagen first blue shifted and then red shifted,the?-helix in the collagen decreased,the?-turn angle decreased,the?-sheet increased,and the irregularity The curl increases,and the number of hydrogen bond breaks in collagen molecules increases with the increase in p H.The research of rheological properties shows that the G',G"and?*of the collagen solution increase with the increase of p H,and the increase range of G'and G"decreases with the increase of p H.Collagen induced by different p H The solutions all show shear thinning,and the rheological curves of the effect of p H on the rheological properties of collagen can be well fitted with the Herschel-Bulkley model,and the degree of fit(R~2>0.9).By studying the effect of p H on the functional properties,secondary structure and rheological properties of collagen,it can provide certain theoretical guidance and technical support for the processing,production and application of collagen and collagen-based products.3)Investigate the effects of different temperatures on the structure,functional properties and rheological properties of the collagen of puffer fish skin.The thermal stability results showed that the Ts value of pufferfish skin collagen was 83.83?,and the Td value was 27.13?.Td was higher than Pacific cod collagen(14.5?).The results of electrophoresis showed that the collagen at 20°C and 27°C was not denatured,and the content of dimer and trimer of collagen decreased with the increase of temperature.The contact angle results show that the contact angle of collagen increases with the increase of temperature,from(64.45±1.09)°to(75.3±3.18)°.The emulsification,emulsification stability,foamability and foam stability of horse face puffer skin collagen all decrease with the increase of temperature.The results of Fourier Infrared Spectroscopy showed that with the increase of temperature,the?-helix of pufferfish skin collagen gradually transformed into random coils;the changes of?-turn and?-sheet of collagen first decreased and then increased.Decrease trend.The results of rheological properties show that the collagen solution of pufferfish skin induced at different temperatures is a pseudoplastic fluid.The Herschel-Bulkley model can be used to simulate the steady-state rheological properties of puffer fish skin collagen induced by different temperatures.By studying the effect of temperature on the functional properties,secondary structure and rheological properties of collagen,we can better understand the effect of temperature on the structure,characterization and properties of collagen,so as to better control temperature during production and processing to control collagen and collagen The performance and quality of the base product. |
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