Study On Ultrasonic-assisted Extraction And Properties Of Collagen From Camel Skin

Animal skin tissue is rich in collagen fibers and has a unique chemical structure and biological activity.Camel skin has the characteristics of large skin,high yield and lower oil content than pig and cow hide,so it can be used as a high-quality source of collagen.To make full use of raw materials and increase the added value of camel products,this study used ultrasonic-assisted extraction of collagen from camel skin,determined the optimal process,and used conventional enzymatic extraction of collagen(PSC)and ultrasonicassisted collagen extraction(UPSC)for comparative analysis of the structure and properties.The main research results were summarized as followed:1.The basic nutrients of camel skin: the moisture,ash,protein and fat content of camel skin after pretreatment were 70.76±0.01 %,0.45±0.10 %,32.87±0.12 % and 4.93±0.36 %,and the collagen content was 51.00 ±1.45 mg/g.2.Ultrasonic-assisted extraction of collagen: Based on a single-factor test,combined with the influence surface analysis method to obtain the optimal extraction process,enzyme loading was 4.50%,solid-liquid ratio was 1:23(g/ml),ultrasonic treatment time was 20 min,and total extraction time was 51 hours.The actual extraction rate of collagen was41.99±1.57%.3.Structural characterization of PSC and UPSC: The SDS-PAGE patterns showed that both PSC and UPSC contain typical bands of type I collagen.It was proved by technical means such as ultraviolet absorption spectrum,Fourier transform infrared spectroscopy and circular dichroism spectroscopy that both types of collagen had a complete structure and high purity.The amino acid composition of PSC and UPSC was similar to the standard type I collagen.Scanning electron microscopy results showed that both PSC and UPSC presented a coiled structure that was entangled with each other.Both had the fibrous properties of collagen,but the spatial structure of UPSC was looser.The results of atomic force microscopy showed that the pore size of UPSC was smaller and the gap between holes was more homogenous.4.Comparative analysis of the properties of PSC and UPSC: The results showed that solubility,foaming,emulsification,water absorption and oil absorption of UPSC were better than those of PSC.However,ultrasound has no significant effect on the hygroscopicity,moisture retention and rheological properties of the collagen obtained by the two extraction methods.Using a rotational rheometer in dynamic frequency and temperature scanning modes,both PSC and UPSC exhibited elastic behavior.It was speculated that the denaturation temperature of both was around 42 ?.In the process of simulating in vitro gastrointestinal digestion,the average particle size of the two gradually decreased.After the digestion,the zeta potential of both was negative,and the absolute value of UPSC potential was greater than PSC.At the same time,the free amino acid results showed that both PSC and UPSC contain eight essential amino acids required by the human body.After digestion,UPSC can identify more types of peptides than PSC.Atomic force microscope observation of the digested products showed that the particles of UPSC were more homogenous.