Study On Evaluation Method Of Fish Fiber And Silver Carp Meat Extrusion Recombination

In the processing of traditional surimi products,the fish muscle fiber is excessively destroyed,resulting in a gelatinous texture and a lack of fiber and meatiness.It is difficult for consumers to taste the fish taste from surimi products without fibrous structure.Making surimi products with fiber taste will be the future research trend.At the same time,the degree of fish fiber needs to be quantified to provide a “yardstick” for subsequent research and development of surimi products with fiber taste.However,the existing fiber evaluation methods have limitations such as strong subjectivity,large error and strict requirements for sample.Therefore,in order to solve the above problems,this paper firstly combined fiber imaging with convolutional neural network to construct fiber degree evaluation method for raw fish and cooked fish systems.Then,the method was applied to study the extrusion and recombination process of silver carp meat.Finally,the formation mechanism of fibrous structure in the extrusion recombination process of fish was studied.This study is targeted at providing a theoretical basis for the development and industrial production of surimi products with fiber taste.The research contents and results are as follows:(1)The evaluation method of fish fiber degree based on convolutional neural networkThe microscopic images of raw fish samples and cooked fish samples with different fiber degrees were collected,and the raw fish fiber image dataset and cooked fish fiber image dataset were established.On the basis of Residual Neural Network(Res Net)model,Edge Feature Attention Network(EFANet)model is obtained by introducing the mechanism of edge feature attention.Compared with other models,EFANet model not only has high recognition accuracy,but also has strong anti-interference ability.EFANet-50 model showed high accuracy,precision,sensitivity,specificity and AUC on raw fish fiber image dataset,with the average accuracy,specificity and AUC of 96.22%,97.92% and 92.51%,respectively.The average accuracy,precision,sensitivity,specificity and AUC of EFANet-18 model were 96.25%,89.66%,89.50%,97.60% and 98.35%,respectively,on the cooked fish fiber image dataset.It was proved that the raw fish fiber degree evaluation method based on EFANet-50 model and the cooked fish fiber degree evaluation method based on EFANet-18 model could objectively and accurately identify the corresponding raw fish fiber degree and cooked fish fiber degree.(2)Study on extrusion recombination technology of silver carp meatThe effects of extrusion parameters such as moisture content,extrusion temperature and screw speed on the fiber degree,apparent morphology;texture and color of fish extrusion recombination products were studied.With the degree of fiber as the target parameter,orthogonal experiments were carried out.The optimal extrusion recombination parameters of fish raw materials with protein content of 58.84%-61.14% and fat content of 6.48%-6.73% were as follows: material moisture content 55%,extrusion temperature 160°C and screw speed 350r/min.The fiber degree of extrusion recombination product can reach 82.11%.(3)Preliminary study on the formation mechanism of extruded reconstituted fibrous structure in silver carp meatThe physicochemical properties and structure of fish were studied before and after extrusion in order to analyze the formation mechanism of the fibrous structure.After extrusion recombination,the protein digestibility in vitro was increased by 9.09%;in the secondary structure,α-helix and β-angle transformed into more stable β-folding and random coil;the fibrous structure of extruded products was mainly maintained by non-covalent bonds,and disulfide bonds were also significantly increased by 27.36%;fish protein molecules did not break down,but cross link to form heavier molecules;the obvious fibrous structures can be seen in the extruded product.Therefore,during the extrusion recombination process,the protein denatured and unfolded as linear molecules.Under the action of screw driving force and internal friction at the cooling die head,the linear protein molecules were oriented and crosslinked with each other,and finally formed a fibrous structure.