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Studies On The Effect And Mechanism Of Gelling Enhancers On The Thermal Gelation Of Hairtail Muscle Protein

Posted on:2016-11-15Degree:MasterType:Thesis
Country:ChinaCandidate:W J LiuFull Text:PDF
GTID:2181330467474330Subject:Food Engineering
Abstract/Summary:PDF Full Text Request
Hairtail(Trichiurus lepturus) is one of the most popular commercial marine fishes in the eastern Pacific Ocean. Literally, it is available material used to produce various seafoods due to its rich reserves and low cost. However, the gelation properties of hairtail muscle protein is very poor, leading to the limited application of hairtail in industrial manufacture. In order to resolve the problem, the interactions between hairtail muscle proteins and three food additives combined as different groups, curdlan alone, curdlan with MTGase, y-PGA with MTGase, were investigated, and frozen hairtail paste as the materials. Effect of the three groups on gelation properties of hairtail muscle protein was investigated by determining the gelling index, such as breaking force and deformation, water holding capacity, whiteness, textural properties (hardness, springiness, cohesiveness, gumminess and chewiness), sensory attributes and scanning electronic microscope images. The mechanism of gelation properties of hairtail muscle protein improved by the three groups of additives was analyzed respectively by evaluating chemical interactions, reactive sulfydryl group and total sulfydryl group, solution of gels as well as SDS-PAGE patterns of myofibrillar protein. The above results provided basic theory for the improvement of thermal gelation properties of hairtail muscle protein. In order to meet the demands for industrial production of hairtail-paste products, optimization of processing conditions to improve gelation properties of hairtail muscle protein was carried out by applying response surface methods to obtain the optimum processing conditions. And the optimum conditions would be a good reference for the real industrial production. The main results of this study were as follows:1) The interactions between hairtail muscle proteins and three food additives combined in different ways, curdlan alone, curdlan with MTGase, γ-PGA with MTGase, were investigated using frozen hairtail paste as the material. The results showed that all the three groups of food additives could significantly improve gelation properties of hairtail muscle protein. Especially, the breaking force and deformation, water holding capacity, textural properties and total points of sensory evaluation increased obviously. 2) Effect of the three groups of additives on the microstructure of gels from hairtail muscle protein was investigated by scanning electronic microscope. Compared with the control without any additives, the sample added with curdlan alone displayed a more dense gel matrix with less and smaller holes and grooves. A much more fine-structured matrix was observed in gels added with curdlan and MTGase in combination. When y-PGA was added into gels combined with MTGase, a similar fine matrix was also observed compared to the discontinuous structure of the control.3) The gelation mechanism of hairtail muscle protein improved by the three groups of additives was analyzed respectively by evaluating chemical interactions, reactive sulfydryl group and total sulfydryl group, solution of gels as well as SDS-PAGE patterns of myofibrillar protein. When preheated at40℃, curdlan alone promoted the formation of hydrogen bonds and hydrophobic interactions, as well as the exposure of SH group. Compared with control, non-disulfide covalent bonds increased significantly when samples were incorporated with curdlan. In gels added with curdlan combined with MTGase, nonspecific associations, ionic bonds and hydrogen bonds decreased and hydrophobic interactions increased. The reactive sulfydryl group was enveloped in hydrophobic groups due to the catalysis of MTGase. More non-disulphide covalent bonds mediated by MTGase occurred due to the synergetic enhancing effect of curdlan.Hydrophobic interactions were observed to increase in gels added with γ-PGA and MTGase. γ-PGA could facilitate the exposure of reactive sulfydryl group out of hydrophobic groups. A much denser inter-and intra-molecular crosslinking of the protein via non-disulphide covalent bonds formed between glutamic residue exposed from hydrolytic γ-PGA and Lys residue of gel protein.4) Orthogonal test was carried out to screen the influential factors and the detailed conditions by determining the gel strength. In gels added with curdlan alone, the desirable gel strength was obtained when parameters were curdlan of4g/100g paste, initial heating temperature of40℃and initial heating time of60min. In gels with curdlan and MTGase, the appropriate parameters were curdlan of4g/100g paste, MTGase of0.4units/g paste, initial heating temperature of40℃and initial heating time of120min. In gels added with γ-PGA and MTGase, the appropriate parameters were γ-PGA of0.6‰, MTGase of0.5units/g paste, initial heating temperature of40℃and initial heating time of120min.5) Optimization of processing conditions to improve gelation properties of hairtail muscle protein was carried out using response surface methods, gel strength as the response value. In gels added with curdlan alone, the predicted value of maximum gel strength,276.35g·cm, was obtained when optimal parameters were curdlan of5.04g/100g paste, initial heating temperature at36.77℃and initial heating time for66.07min. In gels added with γ-PGA and MTGase, the predicted value of maximum gel strength,723.793g·cm, was obtained when optimal parameters were γ-PGA of0.72‰, MTGase of0.54units/g paste, initial heating temperature at37.38℃and initial heating time for121.78min, indicating the model was of great value in the real industial processing.
Keywords/Search Tags:hairtail muscle protein, gelation properties, curdlan, MTGase, γ-PGA, mechanism, optimization
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