Study On The Process And The Yolk Gelation Mechanism Of Drunk Egg

Drunk egg is a kind of egg product,which is made by pickling fresh eggs in the drunk liquor（the mixture of Chinese baijiu and soy sauce）after being shelled.At present,the traditional formula of drunk egg is relatively simple,and the research on the formation of its yolk gel is less.Therefore,this paper first improved the traditional formula of drunk egg,and developed the flavored drunk egg.Then,the changes of gel characteristics and intermolecular interactions during the formation of drunk egg yolk gel under the action of baijiu were emphatically studied through the experiments inside and outside eggshell,providing a theoretical basis for the quality control and improvement of processing technology of drunk egg.The specific research contents and results were as follows:1.In order to enrich the flavor of drunk eggs,three seasonings,namely spices,salt,and sugar,were added to the traditional recipe of drunk eggs to develop the flavored drunk eggs.Through orthogonal experiments and fuzzy mathematical sensory evaluation,the optimal recipe for drunk egg seasoning was optimized.Based on the required amount of baijiu,the optimal ratio of seasonings in the formula of the flavored drunk eggs was:spices 3%,salt 5%,and sugar 5%.The physicochemical indicators,texture and free amino acid content of the flavored drunk eggs obtained by marinating the optimal formula were compared with that of traditional drunk eggs.The results showed that the moisture content,ash content,and pH value of egg yolk of the flavored drunk eggs significantly increased compared to traditional drunk eggs（P<0.05）,while its protein content was lower than that of traditional drunk eggs（P<0.05）.The hardness and cohesion of the flavored drunk eggs were significantly higher than those of traditional drunk egg yolk（P<0.05）,while other textural indexes were not significantly different from those of traditional drunk egg yolk（P>0.05）.In addition,the total content of free amino acids in flavored drunk egg yolk was 5.424 mg/g,which significantly increased compared to traditional drunk egg yolk（P<0.05）,and the amino acid composition was also more abundant.Therefore,the new pickling formula was beneficial for improving the texture and enriching the flavor of drunk eggs.2.In order to study the gelation behavior of drunk egg yolk,duck eggs were directly pickled with baijiu to simplify the pickling of drunk eggs.The results showed that with the prolongation of pickling time,the mositure content,viscosity and oil yield of egg yolk proteins increased（P<0.05）.At the same time,due to the closer combination of protein and water molecules,the hardness and cohesion of egg yolk and the relaxation time T₂₂（immobilized hydrogen protons）decreased（P<0.05）.In addition,the results of fourier transform infrared spectroscopy（FTIR）indicated that during the egg yolk gelation induced by baijiu,theα-helical structures increased,which contributed to the increase of hydrogen bond interactions between protein molecules,and therefore the formed gel structure tended to be stable.Consequently,the gelation of egg yolk during baijiu pickling was the result of the interactions between protein-solvent and protein-protein molecules.3.In order to clarify the induction of baijiu on egg yolk gel,egg yolks were directly treated with different concentrations of ethanol,and the physicochemical properties,microstructure and protein structure of the gel were studied.The results showed that the hardness,the relaxation time T₂₃（flowable hydrogen protons）and Zeta potential of egg yolk gel increased first and then decreased with the increase of ethanol treatment time（P<0.05）,and the hardness of egg yolk gel induced by high concentration（80%）of ethanol was higher than that induced by medium concentration（60%）and low concentration（40%）of ethanol soultions.However,with the continuous penetration of ethanol,the gel structure was damaged to some extent.At this time,the egg yolk gel induced by 60%ethanol was the least affected and had better gel texture.In addition,ethanol treatment changed the secondary structure of egg yolk proteins,and the increase ofα-helics of egg yolk gel induced by 40%and 60%ethanol helped to form the compact gel structure;while the reduction of theα-helics of egg yolk gel induced by 80%led to the structural reorganization of the protein,forming a dense granular gel structure.Therefore,within a certain treatment time,ethanol induced the gel structure to become more stable,and the higher the ethanol concentration,the more obviously it affected on egg yolk gel structure.4.The main components（plasma and granules）of egg yolk were obatined by dilution and centrifugation,and then were induced with ethanol respectively.The egg yolk liquid was used as a control to study the formation mechanism of ethanol-induced egg yolk plasma and granule gels.The results showed that with the extension of treatment time,egg yolk and plasma showed similar gelation behavior under the induction of ethanol.The hardness,T₂₂,and free sulfhydryl content of both showed the trends of first increasing（P<0.05）and then slightly decreasing（P>0.05）,while the hardness of granule gel always showed an increasing trend（P<0.05）.Microstructural results showed that the plasma and granule structures were disrupted to release their components,which then randomly aggregated or combined.In addition,"aggregation band"appeared in the second derivative spectrum of plasma proteins,and the disordered structure of granule proteins increased.In a word,the aggregation of yolk proteins induced by ethanol was mainly attributed to the aggregation of plasma components,while granules enhanced the strength of yolk gel.