Preserved eggs (also known as preserved eggs, colored eggs, colorful preserved eggs, preserved eggs, alkaline eggs, mud eggs, etc.). ) is a specialty of our country and one of the important export commodities. Now its processing technology is introduced as follows. 1. Raw materials The main raw material for processing preserved eggs is duck eggs. In addition, soda ash, lime, salt, tea, yellow lead powder, plant ash, pine and cypress branches are also used. 1. The selection and processing of duck eggs must use good quality fresh eggs to meet the quality standards of high-quality products. 2, materials and their functions The materials used to process preserved eggs must also meet the quality requirements in order to make high-quality, standard preserved eggs. (1) quicklime. Protein of duck eggs can be denatured and solidified into jelly. In addition, in order to ensure the concentration of lye, the lime used must not be damp or placed in the open air for a long time. (2) soda ash. (3) yellow lead powder. Lead oxide, also known as Lithuanian monk. It has two main functions: one is to make the preserved egg protein have a unique blue-black color; The second is to make the protein maintain a certain hardness after solidification, which is convenient for shelling, and it is also complete from the beginning after shelling. (4) salt. It can weaken the spicy taste of preserved eggs, improve the flavor of preserved eggs, inhibit the activity and reproduction of harmful microorganisms, and promote the formation of soup hearts from yolk. However, the amount of salt should not be too much. When it is too much, the coagulation power of protein is poor and the yolk is hard. (5) tea. Tea contains tannins, which is helpful to the solidification of protein, improve the color of preserved eggs and relieve the spicy taste. (6) plant ash. Contains Na2CO, which is helpful for protein solidification. (7) pine and cypress branches. Resins and aromatic substances with special smells help to improve the flavor of preserved eggs. Second, the processing principle 1, the characteristics of preserved eggs, the eggshell is easy to peel off, protein is solidified, and it is light green brown or brown translucent jelly. There are pine needle-like white crystals or patterns in brown protein, and the yolk is semi-solidified. Egg yolk can be clearly divided into dark green, khaki, grayish green, orange and other colors, and there is soup in the egg yolk. The finished product has unique flavor, rich fragrance and less spicy taste, and has a cool feeling after eating. 2. Processing principle Fresh duck eggs can be made into preserved eggs with the above characteristics, because the contents of duck eggs are formed under the comprehensive action of various materials during the production process. Among them, sodium hydroxide plays a major role, which gradually permeates into protein during processing and promotes the solidification of protein. Third, processing methods Although there are many processing methods for preserved eggs, the main technological processes are similar, as follows: 1. The ingredients of preserved eggs produced in China vary from place to place. Now the list of composition standards in Beijing, Tianjin, Hubei and other regions is as follows. Table 1 reference table for standard area and seasonal weight of preserved egg ingredients (kg) Ingredients North Beijing Tianjin Hubei Spring, Summer, Spring, Early Autumn and Late Summer Season 1, Season 2 and Season 3 Fresh duck eggs 400 400 400 500 500 500 quicklime14-15-16/kloc 4.25 3.25-3.5 3.75 calcined lead powder 0.150.150.1-0.15 edible salt 2 2 68. 8+0.5 tea1.51.51.57 2 charcoal ash 1 1 25-3 3.5 pine and cypress branches 0.150. 50 50 50 From the reference table of batching standards, it can be seen that batching standards change with the seasonal change of climate, and the main materials, namely quicklime and soda ash, are also different. At the same time, the quality of duck eggs in summer is not as high as that in spring and autumn, and the yolk floats and deteriorates shortly after the eggs are laid in the tank. Therefore, the dosage standards of quicklime and soda ash should be appropriately raised to accelerate the ripening of preserved eggs and shorten the ripening period. It is better to choose white block ash with high purity and low impurity content for quicklime in the ingredients: plumbum preparatium powder (don't use too much, otherwise it will increase the lead content in the mouth), which is better, purer in quality and better in effect. The ingredients must be ground and sieved, the finer the better, so as to avoid "pig's eye" (that is, granular yellow lead powder corrodes protein and causes black spots in protein), which will affect the quality of finished products. 2. Wash the pot first, and then pour the soda ash (or purple alkali), salt, tea, pine and cypress branches and clear water accurately weighed in advance into the pot to heat and boil. 3, blanking to prepare an empty cylinder (coarse cylinder) or iron drum, first put the quicklime into the cylinder (or barrel), and then put the plumbum preparatium powder and plant ash on the quicklime. Then pour the boiled water (or juice) into the tank while boiling. At this time, when lime meets juice, it will melt by itself, and at the same time, it will release heat and emit high temperature. After the evaporation power in the tank becomes weak, turn it continuously and stir it evenly with a shovel. 4. Fill the jar with soup. Put the selected fresh duck eggs into a clean jar according to the grade or size. Before lowering the tank, the bottom of the tank should be covered with a layer of clean wheat straw to prevent the duck eggs at the bottom from directly colliding with the hard bottom of the tank and being crushed by the multiple layers of duck eggs above. When you put eggs in the jar, you should put them gently and lay them flat layer by layer. Put it about 6- 10 cm away from the tank mouth, cover it with bamboo grate and hold it down with a wooden stick to prevent the duck eggs from floating up after pouring soup. After canning, stir the cooled feed liquid (or feed soup) to make its concentration uniform, and slowly pour it into the tank from one side of the tank according to the required amount until the duck eggs are completely submerged by the feed soup. The temperature of soup should change with the seasons: it should be controlled at about 65438 05℃ in spring and autumn; The lowest temperature in winter is 20℃, and the measurement of soup in summer should be controlled between 20-22℃, preferably below 25℃ ... 5. Technical management After pouring the soup, it will enter the pickling process until the preserved eggs are mature. The technical management of this section is mainly to strictly control the indoor (cylinder room) temperature: the first general requirement is between 2 1-24℃, 7- 10 days in spring and autumn, 3-4 days in summer and 5-7 days in winter. The contents of eggs begin to change, and the protein first becomes thinner, which is called "albumen-clearing period", and the protein gradually changes in about 3 days. At this time, the indoor temperature can be raised to 25-27℃ to accelerate the penetration of lye and other components into eggs. After soaking for about 15 days, the room temperature can be reduced to 16- 18℃, so that the ingredients can slowly enter the eggs. In the curing process, there must be a special person in charge, check the changes of eggs, temperature and the amount of soup every day, and record them at any time, so as to find problems and solve them in time. 6. Under normal circumstances, duck eggs will mature in about 45 days after being canned (about 40 days in summer and 50-60 days in winter). Before taking out of the can, sampling inspection should be carried out in each can, and all duck eggs should be regarded as mature before taking out of the can. When taking out the jar, first take out the wooden stick and bamboo grate cover on the jar, and then take out the mature duck eggs. Listen to the dirt such as lye attached to duck eggs with boiling water in sequence, and put them in a bamboo basket to dry. 7. Wrap qualified eggs selected by quality inspection and grading with mud bags and rice milling. The mud wrapping system consists of 60-70% yellow mud and 30-40% preserved egg soup mixed into paste. When the eggs are wrapped in mud, one egg is wrapped in mud, and each egg needs about 675 grams of mud on average. In order to facilitate storage, preserved eggs wrapped in mud should stop sticking to each other. After wrapping the mud, the eggs should roll back and forth on the rice husk, and the rice husk will stick to the mud evenly. Every 100 egg needs about 500 grams of rice husk. And spray a little salt water properly to make the chaff shell look good. 8. Put the eggs into the jar, put them into the gap or jar, fill the jar mouth or jar mouth with mud and seal them, and then put them into storage. 9. Preserved eggs are generally stored in three ways: (1) in the original tank. (2) The materials are packaged and stored in a cylinder. (3) packaging materials, and then packing or storing in baskets. The storage period of preserved eggs is related to seasons. Generally, the storage period is longer in spring and shorter in summer. Because preserved eggs are a kind of flavor utensils, they are generally not suitable for storage. The temperature in the warehouse should be controlled within the range of 10-20℃, and the altar (altar) or basket (box) containing preserved eggs should be placed in a cool and ventilated place, so as not to be exposed to the sun, and to prevent the preserved eggs from going moldy and deteriorating due to rain or moisture.