Effect Of Ultrasonic-irridation Treatment On Foaming Properties Of Liquid Egg White And Exploration Of Its Action Mechanism

This research is affiliated to Jilin Provincial Department of Science and Technology “nutrition leisure series egg processing key technology and product development” project(20160203013NY).The egg white liquid is not only favored by people because of its rich nutrient content,but also widely used in food processing due to its unique functional properties,among them,foaming is most widely used in foam foods.For foam-type foods such as cakes that require foaming,the better the lathering performance,the better the quality of the processed food.Therefore,it is of practical significance to increase the lathering quality of the egg white liquid.In this paper,ultrasonic-irradiation technology was used to improve the foaming properties of egg white liquid,this method uses pure physical methods to modify egg white protein,avoiding chemical methods that may leave harmful ingredients in food.At the same time,the mechanism of the ultrasonic-irradiation combined technology on egg white was analyzed preliminarily.This can provide an in-depth study of the foaming properties of egg white liquid and the development of egg white liquid.The potential value of the bubble in food provides some reference.At first,the egg whites were stored at 4°C and-20°C for 60 days.Determination of the foaming properties,soluble protein content and pH of egg white with storage time,Comparing the differences in the properties of the two temperatures,the following conclusions were obtained:(1)The changes in the soluble protein content in the egg whites stored at both temperatures are the same,and both are followed by a brief rise followed by a decrease and then an increase.However,the soluble protein content in egg whites stored at-20°C was greater than that stored at 4°C.(2)The change trend of pH of egg white liquid is also the same at both temperatures,both falling first and then increasing.However,the pH at-20°Cbefore 40 days is higher than the pH at 4°C.After 40 days,the pH at-20°C is lower than the pH at 4°C.(3)The foaming properties of egg whites stored at 4°C and-20°C showed a tendency of decreasing gradually,but the foaming properties of egg whites at-20°C were superior to the foaming properties stored at 4°C.Secondly,single-factor and response surface tests were used to optimize ultrasonic-irradiation technology to improve the foaming parameters of egg white liquid.The optimal treatment conditions were irradiation dose of 33 kGy,ultrasonic time of 6 min and ultrasonic power of 300 w.At this time,the foaming property of the egg white liquid was 92.1 %,which was twice that of the untreated one.Then the properties and structure of the egg white liquid treated by ultrasound-irradiation technique were measured.The results showed that the content of soluble protein in the egg white liquid after ultrasonic-irradiation treatment increased,and the pH and particle size decreased significantly;The fluorescence intensity weakened and the order of secondary structure in the molecule decreased.Finally,ultrasonic-irradiation processing of individual proteins in egg albumin is further performed,and then the property change of a single protein was determined.In this paper,egg albumin and egg were selected.The three proteins,transferrin and lysozyme,were determined.The results showed that both the soluble protein content of ovalbumin and lysozyme increased and the soluble protein content of ovotransferrin decreased significantly after ultrasonic-irradiation combined treatment.The pH and particle size of ovalbumin and lysozyme were significantly reduced,while the pH and particle size of ovotransferrin increased.After fluorescence spectroscopy,the fluorescence intensity of ovalbumin,lysozyme and ovotransferrin were decreased after ultrasonic-irradiation treatment.The circular pattern analysis showed that the contents of ?-helix and ?-sheet in the molecular structures of ovalbumin,ovotransferrin and lysozyme were all significantly reduced.This was in agreement with the ultrasound-irradiation treatment of egg whites.Protein secondary structure changes are consistent.Experiments show that ultrasonic-irradiation combined technology can effectively improve the foaming properties of egg white.This technique can reducethe protein structural order of egg albumin,resulting in changes in physical and chemical properties and improving the foaming properties.The technology can be widely used in the production and processing of foaming foods.