Study On The Physicochemical And Emulsifying Properties Of Ovalbumin Modified By Ultrasonically Assisted Glycation

Ovalbumin(OVA)is a very important raw material in food and medical industry,which has high application value.The application prospect of using protein as emulsifier is very broad.However,due to the structure of ovalbumin and the processing process,special processing conditions will make ovalbumin denaturation,so that it has limitations in the preparation of emulsion,which limits the application of OVA.Therefore,it is very important to improve the functional characteristics of OVA by using safe and effective modification means.In this paper,three kinds of reducing sugar on the OVA glycosylation modification,and its physicochemical properties and emulsifying performance for in-depth study,the relationship between the improvement of the physicochemical properties and emulsifying properties,further choose the appropriate sugar type for ultrasound pretreatment assisted glycosylation and.ultrasound assisted glycosylation to modified OVA.The differences between the two ultrasonic methods were explored,and the effects of ultrasonic modification on protein physicochemical properties and emulsification properties were analyzed.This provides a systematic theoretical guidance for ultrasonic-assisted glycosylated modified OVA technology,and provides useful information for selecting OVA as raw material to prepare stable emulsion and expanding the application of OVA in food industry.Specific research results are as follows:(1)At different temperature(55,65,75,85 and 95 ℃),the use of glucose(GLC)and galactose(GAL)and xylose(XYL),the hot and humid maillard reaction to glycosylation modification of OVA,respectively investigates the OVA and three kinds of sugar in the physicochemical properties and emulsifying properties of products under different temperature.The results showed that with the increase of glycosylation temperature,the grafting degree,Browning degree and surface net negative charge content of the OVA-sugar composites all increased,while the surface hydrophobicity of OVA-sugar composites first increased,reached the highest at 65 ℃,and then decreased gradually.At the same time,the structure of the glycosylated OVA was identified by Fourier transform infrared spectroscopy and fluorescence spectroscopy,both of which proved that sugar was effectively grafted into the OVA molecule.XYL had the highest reactivity,OVA-X had the highest degree of graft,Browning,potential,hydrophobicity,and had the highest emulsifying stability at 65 ℃.(2)In different ultrasonic time(20,40 and 60 min),ultrasonic pretreatment assisted and ultrasound assisted glycosylation reaction of OVA were carried out,and the effects of the two ultrasonic methods on the physicochemical properties and emulsifying properties of OVA-X composites were analyzed and compared.After ultrasonic pretreatment for only 20 min,the grafting degree of the product was 31.60%,which was higher than the 18.19% grafting degree of OVA-X obtained at 95 ℃ and the 28.46% grafting degree of OVA-X obtained at 95 ℃.At the same time,its absorbance is much less than the OVA-X obtained at 95 ℃.OVA-X with higher grafting degree and lower Browning degree can be prepared by ultrasonic treatment.Under the same ultrasonic treatment time,the grafting degree of Ultrasound Pretreatment assisted glycosylated modified ovalbumin(UPOVA-X)was higher than that of Ultrasound assisted glycosylated modified ovalbumin(UOVA-X).FTIR and fluorescence spectra showed that the structure of OVA-sugar composites was changed by ultrasonic treatment.The surface hydrophobicity of UPOVA-X and UOVA-X was significantly higher than that of OVA-X.UOVA-X with ultrasonic treatment time of 60 min had the largest Zeta potential change,which was 24.5 m V.The emulsification activity and emulsification stability of the OVA-sugar composites obtained by ultrasonic treatment were significantly improved.The emulsifying activity of OVA-sugar composites increased with the increase of ultrasonic treatment time,and with the increase of ultrasonic processing time,UPOVA-X and UOVA-X emulsion stability were significantly greater than at the start of OVA-X,UPOVA-X emulsion stability is on the rise.However,the emulsification stability of UOV-X reached the peak value at 20 min,and then decreased slightly during a longer ultrasonic treatment time.(3)The emulsion properties prepared by natural OVA,OVA-X and UOVA-X with ultrasonic treatment time of 20 min under adverse conditions were investigated.The results show that with the increase of ultrasonic time,the average particle size of emulsion UPOVA-X and emulsion UOVA-X decreases.In a long period of accelerated experiments,the emulsion prepared by natural OVA significantly increased the size of emulsion droplets during storage after 7days.In contrast,for the emulsion prepared by UOVA-X,the change of the average particle size of the emulsion at the 5th and 7th day was almost negligible,and the change of the microscope image of the emulsion prepared by UOVA-X was less than that of the emulsion prepared by OVA.In the freeze-thaw cycle experiment,when the two freeze-thaw cycles occurred,and when the salt concentration was 0.2 mol/L and the emulsion was heated at 90 ℃for 30 min,the microscopic image of the emulsion prepared by UOVA-X almost did not change,and it still showed dense and evenly distributed small oil droplets inside.The average particle size of the emulsion changed little.Compared with OVA and OVA-X,the emulsion prepared by UOVA-X have better emulsion properties under bad conditions.These findings will provide reference for the preparation and application of emulsion based on OVA.