| In this paper,Nemipterus virgatus surimi(N)and Hypophthalmichtys molitrix surimi(S)were taken as the object of study to analyze the changes of dynamic rheological and gel properties of the mixed surimi combined with the composition of amino acids in the mixture of minced fish gel to reveal the changing rule of the chemical reaction and the protein conformation.The main conclusions are as follows:1.The storage modulus(G')of the mixed surimi gradually increased with the increase in the content of Nemipterus virgatus surimi,and was significantly higher than that of the Hypophthalmichtys molitrix surimi.During the whole heating process,the value of loss modulus G" was significantly lower than G'.When N:S was greater than or equal to 3:1(W/W),G' of mixed surimi was significantly higher than that of Nemipterus virgatus surimi.Compared with N and S,the gel strength of N:S equal to 3:1 was 6514.76 g·mm,which was increased by 3.08%and 92.13%respectively,and the lightness and whiteness were improved,and the cooking loss was reduced by 7.64%and 33.94%,respectively,and the water holding capacity was enhanced.However,when N:S was greater than or equal to 3:1,there was no significant change in the properties of mixed surimi gels(p>0.05).The microstructure of the gel showed that the three-dimensional network structure of N:S equal to 3:1 gel was more dense and the pore size was smaller.2.The total amount of hydrophobic amino acids in the mixed surimi gels was significantly higher than that of Hypophthalmichtys molitrix surimi(p<0.05).Methionine was highly correlated with gel strength(p<0.01),and alanine,isoleucine,histidine,arginine,and the total amount of hydrophobic amino acids were significantly correlated with gel strength(p<0.05),and methionine,tyrosine,histidine and arginine were significantly negatively correlated with hydrogen bonds(p<0.05).When N:S was equal to 3:1,the gel strength of mixed surimi was improved significantly.There were three peaks at 45?,67? and 78?,respectively,and the peak temperature of mixed surimi firstly increased and then stabilized.In the mixed surimi gels,the content of nonspecific association,ionic bond and hydrogen bond decreased firstly and then changed little.When N:S was less than 5:1,the content of disulfide bonds increased.The proportion of the?-helix structure of the mixed surimi gels decreased firstly and then tended to be stable.The ?-turns and ?-sheets structure increased gradually.When N:S was equal to 3:1,the ratio of I850/I830 was the highest,which was 1.26.In the myofibrillar system of mixed surimi with the increase of the content of Nemipterus virgatus surimi:Circular dichroism(CD)spectra showed that the average residue ellipse value[?]increased at the 209 nm and 222 nm of the negative trough,and the maximum peak absorption peak of the UV absorption spectrum increased.While,when N:S was greater than 4:1,the UV absorption photometric value had a downward trend.The maximum emission wavelength shift of fluorescence spectrum changed.In the mixing process of Nemipterus virgatus and Hypophthalmichtys molitrix,the color of MHC band gradually became shallower,and the width of AC band gradually narrowed,and there was little change when N:S was greater than 3:1.The gel strength of mixed surimi gels was significantly negatively correlated with nonspecific association,ionic bond,hydrogen bond and?-helix(p<0.01),and significantly positively correlated with beta fold and disulfide bond(p<0.01).3.During the first period of heating,the breaking force and gel strength were significantly improved.There was no significant difference in the breaking force and the gel strength of N:S equal to 3:1 and 1:0.During the second period of heating,the growth of N:S equal to 3:1 was lower than Nemipterus virgatus surimi.While the gel properties of N:S equal to 1:5 were significantly improved compared with S during the whole heating process.During the first period of heating,the whiteness and lightness of mixed surimi gels from N:S equal to 3:1 and 1:5 were significantly better than that of Nemipterus virgatus surimi,and they reached 77.64,75.46 and 74.82 and 73.54,respectively,after heating 40 min,but there was no significant change with time(p>0.05)during the second period of heating.The hardness of N:S equal to 3:1 was significantly higher than that of two blank groups at 40? for 25 min,and the hardness and elasticity of mixed surimi gels were significantly higher than that of S(p<0.05)during the formation of mixed surimi gels.The micro structure showed that the structure of mixed surim gels was more detailed when unheated,and the network structure was more dense and uniform than Hypophthalmichtys molitrix surimi in the gelation stage,and the network structure of the mixed surimi gels was more compact.4.The contents of tyrosine and methionine in the Nemipterus virgatus surimi were higher than that in the Hypophthalmichtys molitrix surimi.During the two stages heating process,the strength of N:S equal to 3:1 consisted with 1:0.The gel strength of the mixed surimi gel N:S equal to 1:5 was significantly different from S after the first heating process for 20 min,especially during the second stage heating process.The gel strength and growth rate of mixed surimi were significantly higher than those of Hypophthalmichtys molitrix surimi gel.Contents of nonspecific associations and hydrogen bond of the mixed surimi gels gradually decreased.The content of disulfide bond first increased during the heating process at 40?,and then decreased when heated at 90?.During the formation of surimi gel,the content of a-helix structure decreased gradually,contents of ?-turns and?-sheets structure increased gradually.Secondary protein structure changed more obviously when heated at 90?.The content of a-helix was the highest,following by the ?-sheets structure.During the heating period of 40?,the peak value of UV was rising,and the UV absorption peak value decreased during the heating period of 90?.The gel strength was significantly negatively correlated with the nonspecific association,hydrogen bond and a-helix(p<0.01),which had a significant positive correlation with ?-turns and ?-sheets and random coils(p<0.01),and was not related to the disulfide bond(p>0.05). |
PDF Full Text Request