Study On The Effect Of Sodium Tripolyphosphate On The Gel Properties Of Egg White Protein-polysaccharide Complex System

This research is supported by the Science and Technology Development Program of Jilin Provincial Science and Technology Department,Research on Key Technologies of Egg Powder Processing and Quality Improvement(20190301015NY).Egg white protein(EW)is rich in a variety of essential amino acids,which is easy to be absorbed by the human body and low in cost.Due to its good gel properties,EW is widely used in the food industry.The gelling of the EW involves denaturation,aggregation of the EW and formation of gel networks.The morphology and size of aggregates during heating are affected by the medium conditions such as p H,ionic strength and salt type of the system.As a common food additive,solubilizer and p H regulator,sodium tripolyphosphate(STPP)has significant effect on the improvement of EW gel properties.However,the mechanism of STPP affecting the thermal aggregation of EW has not been proved yet.In addition,a large number of studies have shown that the formation of protein-polysaccharide complex can improve the solubility,stability and gel properties of raw protein,and a variety of polysaccharides have been used in protein processing.STPP can affect the electrostatic interaction between protein and polysaccharide,which is expected to regulate the gelation of protein-polysaccharide complex.However,the related literature is scarce.Therefore,in this paper,EW is taken as the main research object.First,the effects of STPP on EW thermal aggregation behavior and rheological properties are explored,and the regulation law of STPP on EW thermal aggregates is clarified.Then,the interaction between anionic polysaccharide ?-carrageenan(CA)and neutral polysaccharide inulin(IN)and EW was selected to explore the effect of STPP on the heat-induced gelation behavior of EW-polysaccharide composite system,and the potential of STPP as a food additive in regulating the gel strength,micro-morphology and water-holding capacity of the protein-polysaccharide composite system was analyzed,which would provide a new idea and theoretical basis for the development of new colloidal structure foods(such as pudding products).The main research results are as follows:(1)The effects of STPP on the physical and chemical properties,structural properties and thermal aggregation behavior of EW solution were analyzed by ultraviolet-visible spectrophotometer,nano-laser particle size analyzer,fluorescence spectrophotometer,rheometer and ultra-low temperature scanning electron microscope.It was found that after adding STPP,the turbidity of EW solution decreased,and the loss tangent and viscosity were lower.STPP can promote the molecular structure rearrangement of denatured protein,and significantly reduce the free sulfhydryl content and surface hydrophobicity of denatured protein.STPP can also promote EW to form small molecule soluble ordered aggregates.(2)Explore the effect of STPP on the gelation of EW-polysaccharide composite system.The effect of STPP on the gelation of EW-polysaccharide(CA and IN for example)composite system was analyzed by UV-vis spectrophotometer,nano-laser particle size analyzer,rheometer,Fourier transform infrared spectrophotometer,texture analyzer and ultra-low temperature scanning electron microscope.It was found that adding CA or IN can improve the hardness and water holding capacity of EW gel,but the ability of IN is weak.After STPP was added,the hardness and water holding capacity of the gel were improved to a greater extent,and the gel formed was denser and more porous.When the addition of STPP is 0.5%(w/v),it has the most obvious effect on the gelation of EW molecules.(3)Explore the application of STPP/EW/ polysaccharide composite system in pudding.On the basis of previous studies,this study took the commercial pudding products as the control group,optimized the pudding formula by single factor and orthogonal test,and took the texture analysis results and sensory scores as the evaluation criteria.Finally,the formula of the new egg white pudding was determined as follows: 8% whole milk powder,5% egg white powder,3% IN,0.4% STPP,0.3%CA,0.1% essence,0.1% citric acid and 0.01% sunset yellow pigment,heat-treated at90? for 20 minutes.Among them,the content of egg white powder is the most influential factor on the texture characteristics and sensory score of pudding products.