| Texture regulation of foamed foods usually requires two affinity surfactants.Traditional amphiphilic small molecule surfactants are prepared by chemical synthesis,which has great limitations in edible and biodegradability.Due to its natural amino acid structure,protein is a macronutrient in human diet and has excellent interfacial activity.Therefore,it is considered to be the first choice of natural foaming agent.Gliadin derived from wheat gluten has strong surface hydrophobicity,and its colloidal particles prepared by anti solvent show outstanding foaming ability and stability.In order to meet the needs of food processing,further improving the foam properties of gliadin colloid particles is a necessary prerequisite for its application in food system.For this purpose,the effects of heat treatment and high energy ultrasonic assisted heat treatment on the structure and foam characteristics of gliadin colloidal particles were investigated in turn.Then,the application potential of colloidal particles before and after treatment was investigated by using typical foam food cake as the carrier.The main research contents and results are as follows:1.The effect of wheat alcohol gliadin dissolved in 70% ethanol on the properties and structure of wheat gliadin colloid particles prepared by anti solvent method under different heat treatment conditions was studied.It was found that the solubility and foam stability of colloidal particles were significantly increased by heat treatment,which were 10% and 85% respectively.The size of colloidal particles is mainly 105-122 nm,ζ Atomic force microscopy(AFM)showed that the aggregation of protein was enhanced.The structure of wheat gliadin was characterized by spectral analysis and small angle X-ray scattering.The results showed that the hydrophobicity and the content of irregular coil increased under high temperature treatment(90℃);The content of disulfide bond decreased and the flexibility of protein structure increased.The enthalpy of wheat gliadin colloidal particles decreased from 54.33 MW to about 3 MW,indicating that the conformation of protein tended to be amorphous with increasing heating time.These conformational changes contribute to the formation of stable interfacial films to better stabilize foam.2.The effects of ultrasonic combined heat treatment on the foaming ability,stability and protein structure of wheat gliadin colloidal particles were studied.The results showed that compared with the natural wheat gliadin colloid particles,the foaming ability and foam stability of the colloidal particles treated by combined treatment increased by 125% and 4% respectively.It was found that the size of colloidal particles decreased and the surface potential increased after combined treatment.In addition,the fluorescence quenching phenomenon of the protein was weakened after ultrasound heat treatment,and accompanied by the decrease of fluorescence intensity α-The decrease of helix content and the increase of irregular curl promoted the exposure of hydrophobic groups and the enhancement of surface hydrophobicity,thus enhancing the diffusion rate of wheat gliadin to the air-liquid interface.3.The effects of high foaming wheat gliadin colloidal particles on the color,morphology,flavor,microstructure and texture of cake were studied.The results showed that the addition of wheat gliadin colloidal particles significantly improved the initiation of cake.Further studies showed that the addition of colloidal particles enhanced the color and elasticity of the cake,and reduced the hardness and chewiness of the cake.With the help of electronic nose and electronic tongue,it was found that the acidity and aromatic response value of the cake were enhanced after adding colloidal particles,and the contents of acids and ketones were higher,and the overall sensory flavor was better.These findings indicate that wheat gliadin colloidal particles can significantly improve the quality of cake. |
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