| Protein is the product of amino acid polymerization and is considered to be one of the important components and structural components in the food system.They serve as hormones,enzymes,structural components(such as muscles and cell walls),and energy sources for animals and plants.They also contribute to the sensory,textural,nutritional and functional properties of food.Today,the trend to consume protein foods as opposed to carbohydrates is increasing due to consumers’ increased awareness of their personal health and well-being.However,the functional properties of some proteins are limited due to their poor water solubility,easy aggregation,or low surface activity and poor emulsion stability.Therefore,modified proteins are also the focus of current research.Glycosylation is one of the main methods of protein modification,which can regulate the structure of proteins and form glycoproteins.It can be used for the non-enzymatic reaction of covalent binding of proteins and sugars.It is an effective method of protein modification to enhance the functional properties of proteins.Although polysaccharide itself has no surface activity,it is adsorbed to the surface of oil droplets adsorbed by protein through electrostatic interaction.When the charge of protein and polysaccharide is opposite,it is conducive to emulsification stability.The main work of this topic is as follows:(1)The effects of three polysaccharides on the structure and emulsifying properties of fish gelatin were studied.Polysaccharide glycosylation is a potentially effective method to cross-link macromolecules with fish gelatin to influence emulsification performance.However,as far as we know,the effect of polysaccharide glycosylation on molecular structure and emulsion stability of fish gelatin has not been studied.Polysaccharide types were selected(Xanthan gum,XG;Guar gum,GG;Konjac glucomannan(KGM).Effects of fish gum(FG)and three polysaccharide Maillard products on the stability of fish oil emulsion at reaction time(0-24 h)and reaction p H(5-9).The emulsifying property of FG-polysaccharide complex was better than that of pure fish gum and pure polysaccharide.In addition,the formation,physicochemical and emulsifying properties of Fg-polysaccharide Maillard products depend on polysaccharide type,reaction time and reaction p H.Maillard conjugate had the best emulsifying properties(FG-GG: 0% emulsifying index;FG-KGM: CI 21.1%±0.7%),and FG-XG Maillard products had the best emulsifying properties of intermediates(intermediates and fish gum)(CI 0%).This work provides useful information for the application of FG-polysaccharide Maillard products in the field of food science to stabilize the emulsion of fish oil.This study comprehensively investigated the possibility of glycosylation modification of fish gelatin by different polysaccharides and its application in the stabilization of fish oil emulsions.First,fish gelatin is modified with three polysaccharides(xanthan gum,guar gum,konjac gum).Secondly,the emulsion containing fish oil stabilized by polysaccharide modified fish gelatin was prepared at p H 5.0,p H 7.0 and p H 9.0,and the storage stability of the emulsion was analyzed.The structure and particle size were characterized by digital camera,optical microscope,electrophoresis,Fourier infrared and ultraviolet spectrophotometer.All the results showed that polysaccharide modification was an effective way to improve the stability of gelatin emulsion.The polysaccharide species,glycosylation time and solution p H value were the main factors affecting the glycosylation structure and emulsion stability of fish gelatin.(2)The effects of three polysaccharides on the structure and emulsifying properties of soybean protein isolate were studied.Cationic polysaccharide(Guar gum),neutral polysaccharide(konjac gum)and anionic polysaccharide(xanthan gum)were used for glycation reaction with soybean protein isolate.The emulsion was homogenized with fish oil on the basis of polysaccharide modified soybean protein isolate under p H5,p H7 and p H9 conditions.The structure and particle size were characterized by digital camera,optical microscope,electrophoresis,Fourier infrared and ultraviolet spectrophotometer.All the results showed that the modification of polysaccharide was an effective way to improve the emulsion stability of soy protein isolate.The polysaccharide species,glycosylation time and solution p H value were the main factors affecting the glycosylation structure and emulsion stability of fish gelatin.(3)To study the effect of three polysaccharides on the structure and emulsifying property of ovalbumin.Glycosylation is a potentially effective method to cross-link macromolecules with oobumin to influence emulsification performance.However,as far as we know,there is no research on the effect of glycosylation on the molecular structure of oobumin and the stability of emulsion.Polysaccharide types were selected(Xanthan gum,XG;Guar gum,GG;Konjac glucomannan(KGM).Effects of OVA and Maillard products of three polysaccharides on the stability of fish oil emulsion at reaction concentration and p H(3-11).The emulsifying property of OVA-polysaccharide complex was better than that of pure ovalbumin and pure polysaccharide.In addition,the formation,physicochemical and emulsifying properties of OVA-polysaccharide Maillard products depend on polysaccharide type,reaction time and reaction p H.This work provides useful information for the application of OVA-polysaccharide Maillard products in the field of food science to stabilize the emulsion of fish oil.The structure and particle size were characterized by digital camera,optical microscope,electrophoresis,Fourier infrared and ultraviolet spectrophotometer.All the results showed that polysaccharide modification was an effective way to improve the stability of ovalbumin emulsion.Polysaccharide species,polysaccharide concentration and glycosylation p H value are the main factors affecting the glycosylation structure and emulsion stability of oobumin.In summary,the influence of different polysaccharides,different glycosylation time,p H of glycosylation and polysaccharide concentration on protein properties and structure was clarified by studying the influence of different polysaccharides on different protein structures and emulsification properties.The effects of different polysaccharides,different glycosylation time,p H of glycosylation and polysaccharide concentration on the solid-liquid phase transition and droplet aggregation rate of protein properties modification were discussed by studying the storage stability of emulsion,the change of emulsion droplet size and the change of emulsion precipitation degree.All the results showed that the modification of polysaccharide was an effective way to improve the stability of protein emulsion.Polysaccharide species,polysaccharide concentration,glycosylation time and glycosylation p H value are the main factors affecting the protein glycosylation fractal structure and emulsion stability.It provides a new direction for the research and development of polysaccharide modified protein-stabilized fish oil emulsion in milk preparation and expands the market and application prospect of protein emulsion. |
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