Optimization Of Production Process And Quality Improvement Of Deshelled Wet Pickled Salted Egg Yolk

Salted egg yolk is popular among consumers because of its loose sandy texture,oil dew phenomenon and unique flavor after heating,and is mainly used as filling or condiment in moon cakes,dumplings,desserts and other products,and has shown a trend of increasing sales and wider application in recent years.At present,the traditional whole egg pickling process has problems such as long production cycle,salty egg white and low utilization rate of whole egg,which affects the comprehensive added value of poultry eggs.In order to solve these problems,the process of pickling salted egg yolk separately from the shell has become a trend and hot spot in recent years,but this new process has problems such as poor forming effect of salted egg yolk,insufficient sandiness,low oil yield and no characteristic flavor.Therefore,in this study,fresh duck egg yolk was used as raw material,and freezing technology was used to improve the yolk forming effect,and ultrasonic and microwave treatments were used to enhance the sandiness and oil yield of salted egg yolk and promote the release of characteristic flavor substances,so as to develop high-quality deshelled wet pickled salted egg yolk and compare the properties with those of commercially available traditional craft salted egg yolk products.The main contents and results are as follows:(1)Comparing the curing effect of dry salt curing,brine curing,freezing dry salt curing and freezing brine curing on salted egg yolks,freezing brine curing was screened as the basic curing process for deshelled salted egg yolks,and the best salted egg yolks were formed with a curing cycle of only 5 d.Then use the oil yield and sandiness as evaluation indexes,investigate the effect of salt concentration,curing liquid addition,drying temperature and drying time on the quality of salted egg yolk through single-factor test and orthogonal test,and determine the best process conditions as follows: salt concentration of 25%,curing salt dosage of 2 m L/each,drying temperature of 45°C and drying time of 51 h.(2)The effect of ultrasonic assisted process on the quality of salted egg yolks was investigated on the basis of frozen brine curing process.The results showed that compared with the control group,the best quality of salted egg yolk was obtained by ultrasonic wave 40 k Hz,800 W treatment for 25 min.The oil yield and sandiness of the samples increased to 63.14% and 70.98%,respectively,the moisture content decreased to 18.21%,the sodium chloride content increased to 2.43%,and the hardness,viscosity and chewiness increased to 2222.25 g,487.94 g·s and 151.59 g.The results of nuclear magnetic resonance,soluble protein,and scanning electron microscopy revealed that the spherical particles of the salted egg yolk broke down and became depressed after ultrasonic treatment,and the state of water molecules in the yolk changed from bound water to free water,weakening the interaction between water molecules and oil,thus promoting the oil yield of salted egg yolk.(3)On the basis of the frozen brine pickling process,the effect of microwave assisted process on the quality of salted egg yolk was investigated,and the optimal process parameter was microwave 400 W treatment for 15 s.Compared with the control group,the oil yield and sandiness of the salted egg yolk increased to 62.88%and 65.49%,the moisture content decreased to 18.32%,the sodium chloride content increased to 2.12%,and the hardness,viscosity and chewiness increased to 1647.81 g,531.46 g·s and 207.28 g,respectively;at this time,the samples had obvious characteristic aroma of salted egg yolk and oil fragrance,burnt taste and fishy taste were the weakest,and the overall flavor was full and salty aroma was strong,which might be related to the obvious increase of sulfide,methyl methane type and aromatic component benzene in the samples after microwave treatment.(4)Compared with frozen brine salted egg yolks,the ultrasonic and microwave groups significantly improved the appearance,sensory quality,basic composition,physicochemical properties and textural characteristics of salted egg yolks,and reached the level of commercially available traditional salted egg yolks.The curing period of both improved techniques was only 5 d,which was about 40 d shorter than that of the commercially available traditional salted egg yolks.The ultrasonic modified salted egg yolks were bright in color,with the best oiling and sanding effect and soft texture,and the appearance was most similar to that of the commercially available traditional salted egg yolks,and the taste salinity was slightly higher than that of the commercially available traditional salted egg yolks;the microwave modified salted egg yolks were orange in color,with good characteristic aroma of salted egg yolks,moderate oiling and sanding,and the taste salinity and chewiness were most similar to that of the commercially available traditional salted egg yolks.