Research On The Characteristic Yellow Preserved Egg Existing In Guizhou Sansui Lead-Free Pickling Technology And Gel Formation

Guizhou Sansui is located in the beautiful Qiandongnan Prefecture,whose climate is awarm and duck egg resources are abundant.However,the duck egg processing technology is relatively scarce,and the egg products are of a single type,which cannot meet the purchase requirements of consumers,thus greatly restricting Sansui duck and the development of duck by-product industry.This thesis takes Sansui duck eggs as the research object,based on the single factor and orthogonal experiments to optimize the development of Guizhou Sansui distinct yellow preserved eggs lead-free pickling technology,and further enrich the variety of preserved egg products,and promote the development of Guizhou Sansui Ma duck and duck byproduct industries.To achieve this goal,the gel formation and color changes during the processing of dinstinct yellow preserved eggs are firstly analyzed and researched to obtain an in-depth understanding on the basic characteristics in the changing trend of gel and color during the processing of preserved eggs.Then,the nutritional quality and volatile flavor components of yellow preserved egg products are analyzed and tested,and the prediction model of shelf life is also constructed to provide theoretical guidance for quality monitoring during production,storage,transportation and sales of enterprises.The key research contents and results are summarized as follows:1.Guizhou Sansui dinstinct yellow preserved egg lead-free pickling technology research and development.After choosing comprehensive score of preserved egg sensory,egg yolk solidity,and color difference as the judgment index,the singlefactor test and orthogonal test optimization of the lead-free pickling process for the dinstinct yellow preserved egg have been carried out,and finally the optimal process combination for the dinstinct lead-free pickling of the yellow preserved egg is determined as:pickling temperature of 15?,NaOH concentration of 4.0%,copper sulfate and zinc sulfate compound solution concentration of 0.4%,copper sulfate and zinc sulfate compound ratio is 1:2,and black tea concentration of 3%,pickling period for 18 days.Under such process condition,the preserved egg gel is complete,the hardness is moderate,the color is golden,the yolk has a high degree of solidification,in which the preserved egg has achieved the best quality,and the sensory evaluation of preserved eggs is 81.35,the yolk coagulation degree is 0.85,the whiteness value(w)of egg white is 30.15,the whiteness value(w)of egg yolk is 46.72,and the comprehensive score is 0.92.2.Research on egg white gel and color changes during the processing of dinstinct yellow preserved eggs:(1)Research on the formation of egg white gel during the processing of distinct yellow preserved eggs.Egg white gel is mainly formed between 6 to12 days,while the main forces in the egg white gel structure are ionic bonds and disulfide bonds.During the period of 0 to 6 days,the pickled lye gradually penetrates into the egg white,while increasing the free alkalinity of the egg white,and the protein structure is destroyed and liquefied.At the same time,the function of strong alkali solution gradually increase the hydrogen bond,hydrophobic effect,disulfide bond and other forces in the egg white.Between Day 6 and Day 12,a large number of chemical bonds interact,and egg white protein re-links freely to form a three-dimensional network fiber structure,which has good resistance to external forces.On the 12th day,the egg white gel has the highest texture property value.At this time,the ion bond and disulfide bond in the egg white account for about 70%of the total force,the egg white hardness is 17.24N,the cohesion is 0.86Ratio,the elasticity reaches 5.03mm,the adhesiveness is 14.9N,and the chewability is 74.58N.(2)The color change of egg white is related to the change of reducing sugar and free amino acid content in egg white.Between Day 0 and Day 12,the content of reducing sugar in egg white decreases rapidly,and the free amino acids decrease and then increase;then,the whiteness value(w)and brightness value(L)of egg white gradually decrease,and the red-green value(a)and yellow-blue value(b)gradually rises,while the color of the egg white gradually turns yellow and dark;after 18 days,the preserved egg is removed from the pickled lye environment and the color of egg white gradually stabilizes;on the 24th-30th days,there is no significant difference in the b,L and w values of egg white.3.Nutritional quality detection and comparative analysis of Sansui dinstinct yellow preserved eggs.The detection of the dinstinct yellow preserved egg product has a pH value of 10.98,and the total number of colonies,coliforms,lead content,and cadmium content have not been detected.The test results are within the scope of the national standard"GB/T 9694-2014 Preserved Eggs" Standard for preserved egg products.The comparative analysis on the quality of the dinstinct yellow preserved egg and two types of commercially available preserved egg(bran-wrapped black preserved egg and clear-pickled preserved egg)reflects that:(1)The texture value of dinstinct yellow preserved eggs is significantly higher than that of two types of commercially available preserved eggs,with hardness of 16.25N,cohesion of 0.87Ratio,the elasticity of 5.54mm,the adhesiveness of 14.1N,and the chewability of 78.25mJ.(2)The essential amino acid index(EAAI)in dinstinct yellow eggs is 98.88,the biological value(BV)is 96.08,and the nutrition index(NI)is 11.16,all of which are higher than the two types of commercially available preserved eggs.In addition,the amino acid contained in the dinstinct yellow preserved egg has a higher nutritional value and more preferred taste composition.(3)The dinstinct yellow preserved egg is rich in 158 kinds of volatile flavor compounds,which is much higher than that of 136 kinds of bran-wrapped black preserved eggs and 123 kinds of clear-pickled preserved eggs.More types of flavor substances constitute the unique flavor of preserved eggs,which plays a important role in enhancing their flavor.4.Prediction of storage shelf life of dinstinct yellow preserved eggs.The changes of sensory and physical and chemical indexes of preserved eggs under different storage temperatures have been tested and analyzed,and then the volatile base nitrogen content is determined as the key index.The kinetic model and Arrhenius equation are adopted to establish the shelf life model of preserved eggs.Based on the model verification of shelf life,the relative error rate between the predicted storage time and the actual storage time is within 10%,which means it has a high degree of credibility,and can be applied to the shelf life prediction of preserved eggs.The fitting model of shelf life is:(?)In the formula:SL stands for shelf life/d;B0 represents the initial value of product quality parameters;B is the quality parameter value when the product is stored at td;R is the gas constant,8.314 J·(mol·K)-1;T is the storage temperature/K.