| The processing of surimi products is an effective way to realize the value-added utilization of large quantities of low-value fish.With the shortage of marine fishery resources and the rapid growth of consumption demand for surimi products,freshwater surimi products have developed rapidly.However,due to the heavy fishy smell of freshwater surimi,it will reduce consumer preference and market value.How to remove the fishy off-odor without affecting the color and texture of freshwater surimi products is an important direction in the research field of aquatic products.At present,the fishy off-odor is removed mainly by improving the rinsing process,adding spices and using microbial fermentation,but the deodorization will affect the texture quality of the surimi gel or introduce other bad flavors.The fishy off-odor problem of freshwater surimi gel products has not been effectively solved yet.Protein oxidation will change the binding ability with flavor components and affect the flavor of the product.Hydrogen peroxide has the characteristics of high safety,single oxidation product,cheap and easy to obtain,and it is a green oxidant that is allowed to be used in food processing in China.Therefore,this article takes silver carp surimi gel as the object to study the effect of hydrogen peroxide treatment on the deodorization of fishy off-odor of surimi gel and its influence on the quality characteristics of gel texture and color.Exploring the way of removing fishy odor by oxidizing surimi with hydrogen peroxide by the construction of myofibril protein and the fishy off-odor substance simulation reaction system.This study has academic value for revealing the ways and mechanisms of oxidation-induced change of surimi gel odor,and at the same time has practical guiding significance for improving the quality of freshwater surimi products and promoting the development of freshwater surimi products processing industry.1.Using SPME-GC/MS combined with GC-O and other methods to confirm the main fishy substances in silver carp surimi gel,and further use sensory evaluation,volatile flavor components,color and texture as indicators.Comparatively studied the effects of three different treatments,including direct addition of hydrogen peroxide(addition),hydrogen peroxide immersion treatment to form surimi gel(immersion),and hydrogen peroxide rinsing surimi(rinsing),on the deodorization of fishy off-odor and quality characteristics of surimi gel influences.The results showed that the main fishy off-odor compounds in silver carp surimi gel were pentanal,hexanal,heptanal,1-octen-3-ol,1-octene-3-one and decanal.Immersion and rinsing could significantly reduce the fishy off-odor of surimi gel,and the deodorizing effect of immersion was better.The sensory evaluation results showed that the descriptive score of the fishy odor of the surimi gel in the immersion group was reduced by57.48% compared with the control group;the odor preference and the overall preference score increased by 81.77% and 38.95%,respectively.The correlation coefficients between the overall preference and odor preference of surimi gel and the sensory score of fishy taste were-0.87 and-0.83,respectively,and the correlation was extremely significant negative correlation(P<0.01).2.Using volatile flavor components,oxidation degree,microstructure and protein conformation as indicators,the effect of different concentrations of hydrogen peroxide immersion treatment on the deodorization of surimi gel and the effect of gel quality were studied.The results showed that when the concentration of hydrogen peroxide reached to 20mmol/L,the content of some fishy off-odor substances was significantly lower than the control group,and the content of 1-octene-3-ol,1-octene-3-one,heptanal,and decanal decreased respectively.Increased the concentration of hydrogen peroxide by 50.28%,44.28%,78.42%,86.70%,and continued to increase the concentration of hydrogen peroxide,with little change in the content of fishy off-odor substances.The content of carbonyl compounds was increased to 2.3 times of the original,and the microstructure of the protein gel was denser,with β-sheet in the secondary structure.The proportion of folding increased from 22.11% to30.12%.Through the analysis of the flavor and microstructure of the different gel parts of the(outside layers,the middle layer and the inner layer),it is found that the hydrogen peroxide immersion treatment mainly affected the content of fishy off-odor substances and the microstructure of the protein gel.The content of pentanal,hexanal,heptanal and 1-octene-3-ol in the outside and inner surimi gel differed by 82.12%,24.06%,50.92% and 35.20%,respectively.The external microstructure of the surimi gel was more uniform and smooth than the inside.In addition,the hydrogen peroxide immersion treatment resulted in different degrees of increase in the strength of the surimi gel,and the residual hydrogen peroxide in the surimi gel was less than 0.1 mg/kg The results showed that the hydrogen peroxide immersion treatment mainly changed the overall flavor of the surimi gel by affecting the fishy off-odor substances in the outside layer of the surimi gel.3.In order to further explore the ways and means of deodorization of surimi gel by hydrogen peroxide immersion treatment,this article constructed a myofibril protein gel-fishy substance simulation system.The binding ability of protein and fishy off-odor substances,chemical forces,and protein secondary structures,gel microstructure,protein oxidation degree,and gel surface hydrophobicity were used as indicators to study the effect of hydrogen peroxide immersion treatment on the combination of myofibrillar protein and fishy off-odor substances.The results showed that: 20-100 mmol/L hydrogen peroxide immersion treatment can significantly reduce the volatilization of fishy off-odor substances in the system.Under100 mmol/L hydrogen peroxide treatment conditions,the binding rate of n-pentanal,n-hexanal,n-heptanal,1-octene-3–ol between protein matrix was increased by 93.71%,90.62%,84.69%,58.54% respectively compared with the control group.The degree of protein oxidation increased significantly,and the carbonyl compounds increased to 8.45 times that of the control group.The surface hydrophobicity of myofibrillar protein was 179.04%higher than the control group.Correlation analysis showed that there was a significant positive correlation between the concentration of hydrogen peroxide and the hydrophobicity of the gel surface,the hydrophobic interaction between protein molecules,and the binding ability of fishy off-odor substances with the protein matrix(P<0.05). |
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