After the fresh eggs are determined by sensory evaluation and egg-beating method, the fresh eggs that are not suitable for processing, such as iron shell eggs, sand shell eggs, oil eggs and cracked eggs, are selected by egg-beating method. Knocking method is to take two duck eggs in your left hand and one duck egg in your right hand, and knock gently one by one. Never let two eggs collide with each other, or a cracked or cracked duck egg will not be easily found. When knocking, knock at both ends first, then knock at the waist, knock at the wheel, and knock everywhere. Anyone who hears a dumb sound means that the eggshell has a small crack (small crack), which is also called cracked egg; And the sound like steel balls colliding is an iron shell egg.
2, ingredients formula
(1) Spring, autumn and winter: 0.55 kg of lead-free preserved egg curing agent core, 5 kg of salt, tea powder 1 kg (purity 96%), 5.5 kg of sodium hydroxide (or 7.5 kg of 98% soda ash, lime block 14 kg instead) and water/.
(2) Summer: 0.6 kg of lead-free preserved egg curing agent core material, 5 kg of salt, 0.5 kg of tea powder (purity 96%), 6 kg of sodium hydroxide (or 8.2 kg of 98% soda ash and 15 kg of lime block instead), and 0/00 kg of water.
3, batching operation procedures
Firstly, salt, tea powder and sodium hydroxide (or soda ash and lime) are put into a mixing tank, then water is added and stirred until the materials are completely dissolved, and the temperature of the materials is reduced to room temperature; Then use a little warm water to dissolve the core material of the lead-free preserved egg curing agent, then pour the core material into the above-mentioned liquid and mix it evenly, and let it stand for 48 hours to make the upper and lower layers uniform.
4. Detection of effective concentration of feed liquid
The effective concentration of feed solution is detected by acid-base neutralization titration, and the total alkalinity is usually determined in the range of 4.5 ~ 5.0%. If the manufacturer does not have the conditions temporarily, it can also be tested by the following two empirical methods. First, take the suggested formula as the center and make a small sample. The deviation of alkali concentration is about 10%. If all three small samples are good, it means that the feed liquid formula is suitable. If the three samples are not completely satisfied, please adjust the above formula appropriately in order to find the most ideal formula. Secondly, taking egg white as raw material, take a spoonful and put it into the feed liquid of a spoonful of contents. If solidification 15 minutes, hydration for 60 minutes, it shows that the feed liquid concentration is moderate; If water is added for 30 ~ 45 minutes, it means that the feed liquid concentration is too high and needs to be diluted with water appropriately; If hydration takes 60 ~ 70 minutes, it means that the concentration of feed liquid is too low and raw materials need to be added properly.
5. Fill the jar and soup
The selected fresh duck eggs should be put into a clean jar in stages, and should be handled with care. Eggs should be placed at a lower place from the surface of the tank, about 6 ~ 10 cm from the mouth of the tank, covered with an eye bamboo net, and pressed with a wooden stick to prevent duck eggs from floating after pouring soup. Stir and cool the completely cooled feed liquid 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 liquid. Don't pour the soup violently, lest you break the eggs and waste the liquid. Fill the soup and let it stand until the duck eggs are marinated in the soup. The temperature of soup should change with the seasons, and should be controlled between 20 ~ 22℃, preferably below 25℃.
6. Strengthen technical management
After the soup is poured, it enters the pickling process until the preserved eggs are mature. The technical management at this stage is closely related to the quality of finished products. First, the indoor (tank) temperature is generally required to be between 265,438+0 ~ 24℃. Duck eggs are soaked in soup for about 7 ~ 65 days, 438+00 days in spring and autumn, 3 ~ 4 days in summer and 5 ~ 7 days in winter. At this time, the indoor temperature can be raised to 20 ~ 27℃ to accelerate the penetration of lye and other ingredients into eggs, and promote the solidification and discoloration of preserved eggs and timely maturity. After soaking for about 15 days, the indoor temperature can be reduced to 15 ~ 18℃, so that the feed liquid can slowly enter the egg and alleviate the change process. Different regions have different requirements for indoor temperature. Too high or too low temperature should be avoided. Too high will explode, too low will affect the curing discoloration. Therefore, when the temperature is too high in summer, some cooling measures can be taken; When the temperature is low in winter, appropriate heat preservation measures can be taken. Where conditions permit, the cylinder room is located in the basement, which is warm in winter and cool in summer. During the curing process, a special person should be responsible for regular observation and inspection, so as to find problems and solve them in time.
7, out of the cylinder
Preserved eggs that have matured after inspection will be taken out of the jar. The soaking time is 30-40 days. Generally, the soaking time is longer in low temperature season; Soaking time is shorter in high temperature season. Eggshells are fragile after soaking, so be careful when taking them out of the jar. Operators should wear rubber gloves to avoid burning fingers. After the preserved eggs are taken out of the tank, the dirt on the eggshells of the preserved eggs should be cleaned with 1.5 ~ 1.8% caustic soda solution or the supernatant of the preserved eggs. If it is washed with cold boiled water, it should be wrapped in mud or waxed in time.
8. Quality inspection
Before coating preserved eggs, quality inspection must be carried out to eliminate broken eggs, bad eggs and inferior eggs to ensure the quality of preserved eggs. The inspection method is mainly sensory inspection, supplemented by lighting inspection. These methods are "one observation, two adjustments, three shakes, four bullets, five photos and six peeling inspections".
(1) One point of view: observe whether the eggshell is complete and the shell color is normal, and remove damaged eggs, cracked eggs, black-shelled eggs and larger black-patched eggs.
(2) Second, weigh the eggs by hand. Take an egg in your hand and throw it up 5 ~ 20 cm high for several times to identify the elasticity of its contents. If it is slightly elastic and heavy, it is a high-quality preserved egg; If it is elastic, it is a big preserved egg; If it is inelastic, it is a preserved egg with water ringing or a rotten preserved egg.
(3) Three shakes: by hand. This method is a supplementary test for inelastic preserved eggs. The method is to hold both ends of the preserved egg with your thumb and middle finger, and shake it up, down, left and right two or three times in your ear to hear that there is no water. Good eggs have no water noise, while preserved eggs or rotten eggs have water noise.
(4) four bombs: that is, flick your fingers. Place the preserved egg in the palm of your left hand, and gently pat both ends of the egg with your right index finger. If the voice is soft "special" or "special", it is a good egg, if it is hard "Germany" or "Germany", it is a bad egg.
(5) Five photos: namely light perspective. If the preserved eggs are mostly black (dark green) and the small heads of the eggs are yellowish brown or red, they are high-quality preserved eggs. If most or all eggs are yellowish brown and move slightly, they are immature eggs. If an egg has a black shadow and a bubble shadow that turns back and forth, it is a water-ringing egg. If one end of an egg is dark red, it is a rotten egg.
(6) Peeling inspection: Peeling inspection of preserved eggs, first observe the appearance, color and hardness. Then cut it lengthwise with a knife, observe the internal yolk, protein and color, and finally taste it. If the protein is bright and clean, it is well separated from the shell and is brown or tea-blue translucent; The yolk is dark green or grass green, the yolk is small orange, the smell is fragrant and delicious, and it is a high-quality preserved egg. If the protein sticks to the shell, rotten head, or even liquid water, the more serious yolk is yellow-red, hard and has a spicy alkaline taste, indicating that the egg was hurt by alkali. If the protein is soft, the yolk is thick and smells like an egg, it is an incomplete preserved egg. If the protein is well solidified and the yolk is yellow, it is a preserved egg, which will turn yellow when exposed to the air. Although this kind of preserved egg is edible, it lacks the unique flavor of preserved eggs.
9, coating quality
(1) Mud-coating and bran-coating: Mud-coating and bran-coating should be done in time after the preserved eggs are taken out of the can. It has three functions: first, it protects the eggshell from damage, because after fresh eggs are soaked, the eggshell becomes brittle and easily damaged. Second, extend the shelf life to prevent preserved eggs from contacting the air or being contaminated by bacteria. Third, promote the maturity of preserved eggs, and increase the protein hardness (especially the preserved eggs with soft and big hearts in protein due to high temperature). Mud coating and bran wrapping can be made into thick paste by adding yellow mud into the egg soaking liquid, and rubber gloves should be worn when wrapping mud. Each egg is wrapped with 70-80g of mud, and the thickness of the mud is 2-3mm. After the mud is wrapped, stick a layer of chaff shell on the surface and wrap it with plastic film.
(2) Coating: Compared with coating mud from chaff, this method is sanitary, beautiful and convenient. This method uses the lead-free preserved egg preservative film developed by the livestock product processing research group of the Animal Husbandry Institute of Zhejiang Academy of Agricultural Sciences, and wraps a layer of film on each preserved egg to achieve the purpose of quality guarantee.
10, storing
Preserved eggs generally have three storage methods:
(1) Original storage: that is, extending the storage date of mature preserved eggs and continuing to store them in the original storage. Generally, they can be stored for 3 to 5 months, and the quality remains unchanged.
(2) The packaged eggs are stored in the jar: that is, the eggs are wrapped in the whole material and sealed in the jar, and the storage period can reach about half a year.
(3) After packaging, storage in boxes or baskets: eggs are packed in whole materials, packed in nylon bags instead of jars, packed in cartons or bamboo baskets and stored in warehouses. The storage period can reach 3-5 months, but when the temperature is high in summer, cartons or bamboo baskets are generally not needed, and it is best to store them in cans.
The storage period of preserved eggs is also related to the season. Generally, the storage period is longer in spring and shorter in summer. As preserved eggs are a kind of flavor food, they should not be stored for too long. The temperature in the warehouse should be controlled within the range of 10 ~ 20℃, and the jars (cans) and baskets (boxes) containing preserved eggs should be placed in a cool and ventilated place to avoid sunlight, rain or moisture, so as to avoid mildew and deterioration of preserved eggs.
1 1, quality index of lead-free preserved eggs
(1) sensory index
① Appearance: The mud layer and rice husk of the mud-wrapped egg should be thin and even, slightly moist, and the paint applied to the egg should be even. Mud-covered eggs, painted eggs and naked eggs must not be moldy, and the eggshells should be clean and complete.
2 egg shape: the egg is complete, shiny, elastic, pine-flowered and non-sticky. Preserved eggs with a heart are generally or slightly shaped, and preserved eggs with a hard heart are hard or slightly hard.
③ Egg color: protein is translucent blue-brown or brown, with dark green yolk and obvious multicolor layers.
Smell: It has the unique smell and taste of preserved eggs, no peculiar smell, no bitterness, no astringency, no spicy taste and a long aftertaste. Hard-core preserved eggs are slightly spicy.
(2) Physical and chemical indexes
Humidity,% 66 ~ 70
Total alkalinity, meq/ 100g 5 ~ 10.
Arsenic (As), mg/kg < 0.5
PH value (diluted with115) > 9.5.
(3) bacterial index
Number of bacteria, < 500 per gram.
Escherichia coli, each/100g > 30
No pathogenic bacteria (Salmonella) can be detected.