Mechanism Clarification Of The Foam Performance Of Egg White Proteins Influenced By Sugars Based On Interface Characteristics

Egg white protein is widely used in baking products because of its excellent foaming ability,which can improve the bulkiness of food system.At present,chemical and physical methods are mainly modification methods of egg white proteins,which have obvious limitations in industrial application.Sugar addition has the advantages of high repeatability,simple operation,low cost and easy industrialization.However,the improvement mechanism of different molecular weight sugars on foam characteristics of egg white protein system is still unclear.In this paper,the effects of different molecular weight sugars on the physicochemical properties,foam characteristics and application properties of egg white proteins were investigated.The mechanism of the improvement effect of sugars on the foam properties of egg white proteins was clarified based on the gas-water interface characteristics,which provides theoretical basis for sugars as an improver of foaming quality of egg white proteins.Firstly,the effects of monosaccharides(glucose)and oligosaccharides(sucrose and maltodextrin)on the foam properties of egg white protein were investigated.The results showed that the foam ability and foam stability of egg white proteins significantly increased after adding 3% sugars,in which the foam ability of egg white liquid with 3% glucose and maltodextrin were increased by 14.6% and 16% respectively.This result can be attributed that the hydrophilic sugar may lead to the hydration layer’s destruction of egg white proteins,thus exposing its hydrophobic domain and reducing the gas/water interfacial tension.In addition,the addition of low molecule sugars increased the apparent viscosity and viscoelasticity of egg white protein liquid,which was conducive to the formation of highly viscoelastic interface films during the foaming process,and thus endowed the foam with excellent anti-coalescence ability.Principal component analysis and hierarchical cluster analysis showed that maltodextrin was a good choice in improving the foam performance of egg white liquid.Secondly,the effect of drying treatment on foam characteristics of low molecule sugaregg white protein complex system were investigated.The results showed that high temperature spray drying significantly changed the structure of egg white proteins,weakened interface molecular adsorption and expansion rate of egg white proteins and the viscosity of reconstituted egg white liquid,thus decreasing the foam properties of egg white proteins.Furthermore,the foam performance and physicochemical properties of low molecule sugar-egg white protein composite system were compared before and after drying.It was found that the positive effect of low molecule sugar on the foam properties of egg white protein was significantly weakened after drying.This result might be linked to the significant decrease of reconstituted sugar-egg white liquid.Thirdly,the effect of polysaccharides(xanthan gum,locust bean gum and guar gum)on the foam properties of egg white protein was investigated.Rheological analysis showed that the addition of polysaccharide could significantly improve the foam ability of egg white proteins by increasing the viscosity of the system and the interfacial adsorption rate of protein molecules.Foam kinetics analysis found that polysaccharides were effectively in increasing foaming rate.In a word,the selected polysaccharides were superior to low molecule monosaccharides and oligosaccharides in improving the foam properties of egg white proteins.Finally,the egg white protein powder with guar gum was used to prepare sugar substitute cake.The results indicated that cake quality and sensory score was higher for medium sucrose(90 g)group and erythritol partial substitution group(sucrose : erythritol=2 : 1)than other groups in terms of lower specific gravity of cake batter,cake hardness,chewiness,baking loss rate,and higher cake specific volume,good cake color and appearance.Moreover,the addition of guar gum can significantly improve the structural stability of cake,which may be related to the formation of rigid crosslinking network between polysaccharides and proteins.The above results provided a theoretical and practical basis for the application of sugars as one of the modifying agents in the baking foods based on the foam of egg white proteins..