| Our country is rich in natural plant resources and freshwater resources.Select the appropriate plant extracts to add to the surimi product can make a kind of nutritious and delicious food deeply loved by consumers. Silver carp is one of "four domestic fishes" in our country widely distributed with large number and low price. Further processing silver carp for surimi gel products scientifically can make full use of freshwater resources, rich the silver carp product structure and improve the edible value of silver carp. This paper mainly studies the influence of different plant extracts (konjac glucomannan with different degree of deacetylation, sodium alginate, catechins) and heat treatment (121℃,10 min) on the contents of amino acids of silver carp surimi, gel properties and the change of various chemical interactions in the process of gel formation thus lay theoretical foundation and provide experimental basis for effective control of gel formation and the development of high quality surimi products. The main research conclusions are as follows:1. The surimi gel properties have the larger changes after adding different degree of deacetylation of konjac glucomannan. Konjac glucomannan with different degree of deacetylation significantly increased the hardness, gumminess and chewiness of surimi gel, and the value of hardness and chewiness reached maximum when the degree of deacetylation of konjac glucomannan was number DK4. The gumminess was proportional to the degree of deacetylation of konjac glucomannan. The cohesiveness and adhesiveness of surime gel improved after adding konjac gum, but the change is not obvious. The effect of the konjac glucomannan with different degree of deacetylation on the surimi gel springiness was not big. With the increased degree of deacetylation of konjac glucomannan added in surimi gel, the balance coefficient of elasticity Eo and decay coefficient of elasticity E1 appeared the trend of increased firstly and then decreased. The whiteness values of surimi gel added konjac glucomannan with different degree of deacetylation were smaller than those were not added overall. Adding a certain degree of deacetylation of konjac glucomannan can reduce the cooking loss rate of silver carp surimi and improve the quality of the surimi gel.Heat treatment also influenced surimi gel properties with different degree of deacetylation of konjac glucomannan. Surimi gel added with different degree of deacetylation of konjac glucomannan after heat treatment can significantly increase its hardness and chewiness, the adhesiveness and cohesiveness of surimi gel with different degree of deacetylation of konjac glucomannan after heat treatment decreased, but the change was not obvious. The springiness of surimi gel with different degree of deacetylation of konjac glucomannan increased after heat treatment, and the springiness of number DK2 was the best. The hardness, adhesiveness, cohesiveness and chewiness of surimi gel with konjac glucomannan which degree of deacetylation in DK1-DK5 after heating treatment were less than those without heat treatment. With the increased degree of deacetylation of konjac glucomannan added in surimi gel, E0 and relaxation time τincreased overall and E1 appeared the trend of increased firstly and then decreased. E0. E1 and τof surimi gel added konjac glucomannan with different degree of deacetylation after heat treatment were smaller than those were not heat treatment except E0, E1 in number DK2. The whiteness values of surimi gel added konjac glucomannan with different degree of deacetylation after heat treatment were smaller than those were not heat treated, but the variation was not abvious and the change was small overall.2. Sodium alginate significantly increased the adhesiveness and cohesiveness of surimi gel, while had little effect on the hardness, springiness, gumminess and chewiness. E0. E1 and τof surimi gel reached maximum when the sodium alginate addition was 0.3% and the hardness was the biggest and viscoelasticity was the best. The whiteness values of surimi gel with 0.2% and 0.4% concentration sodium alginate were smaller than those were not added overall while adding 0.3% and 0.5% concentration improve the whiteness. Adding a certain amount of sodium alginate can reduce the cooking loss rate and improve the quality of the surimi gel.The hardness, cohesiveness, gumminess and chewiness of surimi gel with sodium alginate reduced after heat treatment while the adhesiveness and springiness increased. The hardness, springiness, gumminess and chewiness of surimi gel with sodium alginate after heating treatment were less than those without heat treatment while those adhesiveness and cohesiveness were higher. E0 and τof surimi gel added sodium alginate after heat treatment were smaller than those were not heat treatment and E0. E1 reached maximal and τminimal when the sodium alginate concentration was 0.2%, thus the hardness of surimi was biggest and springiness the best. The whiteness values of surimi gel added sodium alginate after heat treatment were appeared the trend of increased firstly then decreased and it reached maximal when the sodium alginate concentration was 0.3% while the whiteness showed lower than those were not heat treated when the sodium alginate concentration bigger than 0.4%.3. Catechins reduced the hardness, gumminess and chewiness of surimi gel, while increased adhesiveness and cohesiveness and had little effect on the springiness. E0, E1 and τ of surimi gel reached maximum when the catechins addition was 0.05% and the hardness was the biggest and viscoelasticity was the best. The whiteness values of surimi gel with catechins showed a trend of decrease overall, and the cooking loss rate increased thus reduced the quality of the surimi gel.The hardness, cohesiveness, gumminess and chewiness of surimi gel with catechins reduced after heat treatment while had little effect on adhesiveness and springiness. The hardness, springiness, gumminess and chewiness of surimi gel with catechins after heating treatment were less than those without heat treatment. E0, E1 reached minimal and τ maximal when the catechins concentration was 0.2%, thus the hardness of surimi was smallest and springiness the worst. Eo and τ of surimi gel added catechins after heat treatment were bigger than those were not heat treatment and τ were smaller than those were not heat treatment when the catechins concentration was 0.05%. The whiteness values of surimi gel decreased with the catechins added increased but those all higher than surimi gel without catechins and whiteness of surimi with heat treatment were lower than those without heat treatment. |
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