| In recent years,the salamander farming industry has been booming due to increasing market demand and high return on investment.The meat of giant salamanders is tender,delicious,and has unique nutritional and medicinal value,and is now being brought to the table as well as to the field of medicine and beauty.This process inevitably generates a large amount of processing byproducts such as skin,viscera,bone,and mucus,which are often discarded due to little research and labor-intensive treatment,resulting in environmental pollution and waste of resources.Based on this situation,this project takes giant salamander bone as the research object to explore the basic nutritional composition of salamander bone,the extraction,purification and characterization of collagen,antioxidant activity and the development and utilization of snack food,the main results are as follows:1.When bones are taken from slaughtered salamanders,many salamander muscles and fats are often attached,which need to be manually removed to obtain pinkish-white,thick and hard salamander bones.The analysis of the basic nutritional composition of fresh salamander bones showed the following results: the ash and protein content of fresh salamander bones were mainly 47.23±0.33 g/100 g and 22.46%±1.78 g/100 g,respectively.the fat content of salamander bones was slightly higher than that of other fish bones,at 14.92±0.67 g/100 g.the moisture content was 11.09±1.55 g/100 g.P,Mg and Ca have the highest proportion in salamander bone,and also have essential trace elements Zn,Cu and Se,which are potential sources of trace element supplementation.The content of unsaturated fatty acids in salamander bone is 70.32%,including 27.87%polyunsaturated fatty acids,and the content of linoleic acid,EPA and DHA in salamander bone is rich,with 8.11%,6.7% and 4.39% respectively2.The best single-factor experimental conditions were obtained by single-factor experiment and response surface method,and the best single-factor experimental conditions were 1:20 for liquid to material ratio,300 U/mg for enzyme dosage and 48 h for extraction time.Design response surface optimization experiments based on this condition.The optimal extraction conditions for collagen were predicted to be 1:10.425,249.7 U/mg of enzyme,and 42.3 h.The conditions were adjusted according to the actual situation,and the validation experimental conditions were set to 1:10,250 U/mg of enzyme,and 48 h.Under these conditions,the extraction rate of giant salamander bone collagen was 5.71% ±0.88%,and the error was about 9.96% compared with the predicted value of 5.141%,indicating that the model is a good fit and can effectively predict the optimal experimental conditions for the extraction process of giant salamander collagen.3.The compositional structures and properties of salamander bone acid-soluble(ASC)and enzyme-soluble(PSC)collagen were analyzed and compared by Fourier infrared spectroscopy,SDS-PAGE,amino acid analysis,solubility,DSC,and scanning electron microscopy.The enzyme-soluble collagen was separated and purified using affinity chromatography,and the molecular weights of the purified samples were determined.The antioxidant activities of the purified proteins were examined and evaluated by DPPH radical scavenging activity,ferrous ion chelating activity,and superoxide anion scavenging activity,and the results were as follows: The yields of ASC and PSC were 10.71% and 5.71%,respectively.The stable triple helix structure of collagen was revealed by Fourier infrared spectroscopy.The SDS-PAGE electrophoresis pattern showed that both samples were type I collagen with a high level of subamino acids(179-187/1000 residues).The sample has the highest solubility at p H6..The thermal denaturation temperature(45.78-46.51°C)was significantly higher than that of marine and freshwater fish species.Under SEM,collagen showed dense lamellar and irregular pore-like shapes.These results suggest that salamander bone collagen has similar properties to mammalian collagen and it is a potential source of collagen..The enzyme-soluble collagen was purified using affinity chromatography,and the molecular weight of the purified protein was about 52 k Da as measured by SDS-PAGE electrophoresis experiments.The antioxidant activity was measured by free radical scavenging activity and metal ion chelating activity,and the results showed that although the antioxidant capacity of salamander bone collagen was weaker than that of VC,its antioxidant capacity also increased linearly with the increasing concentration of the sample,which was a good antioxidant.4.To explore the production process of salamander bone leisure food and the best experimental conditionsof giant salamander bone snack food,take sensory evaluation as the index,and the deodorization solution was firstly screened,and then the best baking conditions were obtained using single-factor experiment and response surface method.The best single-factor experimental conditions obtained were: salamander bone size 2.5cm×2cm,baking time 2h,and baking temperature 120℃.Based on this,a three-factor,three-level response surface experiment was designed and a quadratic regression model was designed to predict the sensory scores of baked salamander bones,and the best baking conditions were obtained as follows: salamander bone size2.5cm×2cm,baking time 2.4h,and baking temperature 116℃.Under this process condition,the baked salamander bone sensory weighted average score could reach 8.87,with an error of about 1.36% from the predicted value of 8.992,which proved that the model had a good fit and could effectively predict the optimal experimental conditions for the baking process of salamander bone. |
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