1. Selection of fresh eggs
After the fresh eggs are determined by sensory identification and egg-photography, the iron-shell eggs, sand-shell eggs and oil eggs are then picked out by the egg-breaking method. , cracked eggs and other fresh eggs that are not suitable for processing; the method of knocking is to hold two duck eggs in the left hand and one duck egg in the right hand, and knock them gently one by one. Do not knock the two eggs against each other, otherwise the duck eggs will break or have small cracks. Not easy to check out. When knocking, hit both ends first, then hit the waist, rotate the wheel and hit everywhere. Whenever you hear a hoarse sound, it means there are small cracks in the eggshell. Such small cracked eggs are also called cracked eggs; while a sound like a steel ball colliding is an iron-shelled egg.
2. Ingredient formula
(1) Spring, autumn and winter: 0.55 kg of lead-free preserved egg marinade core material, 5 kg of salt, 1 kg of ground tea (96 purity) , 5.5 kg of sodium hydroxide (or replace with 7.5 kg of 98 soda ash and 14 kg of lime blocks), 100 kg of water.
(2) Summer: 0.6 kg of lead-free preserved egg pickling preparation core material, 5 kg of salt, 0.5 kg of ground tea (96 purity), 6 kg of sodium hydroxide (or 8.2 kg of 98 soda ash, lime 15 kilograms of block instead), 100 kilograms of water.
3. Ingredients operating procedures
First put salt, tea powder, sodium hydroxide (or use soda ash, lime) in the mixing tank, then stir with water until completely dissolved, wait The temperature of the material drops to room temperature; then use a small amount of warm water to dissolve the core ingredient of the lead-free preserved egg marinade, pour it into the above material liquid, mix well, and let it stand for 48 hours to make the upper and lower layers of the material liquid even.
4. Detection of effective concentration of feed liquid
Use acid-base neutralization titration method to detect the effective concentration of feed liquid. Usually the total alkalinity is determined to be in the range of 4.5 to 5.0. If the manufacturer temporarily If the conditions are not met, you can also test according to the following two empirical methods. One, take the recommended formula as the center, and make small samples with an upper and lower deviation of about 10 in alkali concentration. If the three samples are all good, it means that the material liquid formula is suitable. If you are not completely satisfied with the three samples, please adjust the above formula appropriately to find the most ideal formula. Second, use egg white as the raw material, take a spoonful and put it into the material liquid with a content of one spoonful. If it solidifies in 15 minutes, and then turns into water after 60 minutes, it means that the concentration of the material liquid is moderate; if it turns into water in 30 to 45 minutes, it means that the material liquid has a moderate concentration. If the concentration of the material liquid is too high, water needs to be added appropriately to dilute it; if it takes 60 to 70 minutes to dissolve the water, the concentration of the material liquid is too low, and raw materials need to be added appropriately.
5. Filling the vat and filling the soup
The selected fresh duck eggs are put into clean vats in different grades. They should be handled with care and the eggs should be placed low away from the surface of the vat. , install it about 6 to 10 cm from the mouth of the tank, add a bamboo mesh cover, and press it with a wooden stick to prevent the duck eggs from floating after filling the soup. Stir the cooled liquid to make the concentration uniform, and slowly pour the required amount into the tank from one side of the tank until all the duck eggs are submerged in the liquid. When filling the soup, be careful not to pour it violently to avoid breaking the eggs and wasting the liquid. After the soup is filled, let it sit until the duck eggs are marinated in the liquid. The temperature of the soup should vary with the seasons and should be controlled between 20 and 22°C, preferably below 25°C.
6. Strengthen technical management
After the soup is filled, the pickling process begins, until the preserved eggs are mature. The technical management work at this stage is closely related to the quality of the finished product. The first is to master the The indoor (in-tank) temperature is generally required to be between 21 and 24°C. The duck eggs are immersed in the soup for 7 to 10 days in spring and autumn, about 3 to 4 days in summer, and about 5 to 7 days in winter. The contents begin to change, the egg whites first become thinner, and then gradually solidify over about 3 days. At this time, the indoor temperature can be increased to 20-27°C to accelerate the penetration of alkali and other ingredients into the eggs, promote the coagulation and discoloration of the preserved eggs, and make them mature in time. After soaking for about 15 days, the indoor temperature can be lowered to 15-18°C to facilitate the use of eggs. The liquid material slowly enters the egg, which eases the change process. The indoor temperature requirements in different regions are also different. The temperature should be avoided to be too high or too low. If the temperature is too high, it will burst, and if the temperature is too low, it will affect the solidification and discoloration.
Therefore, when the temperature is too high in summer, some cooling measures can be taken; when the temperature is low in winter, insulation measures can be taken appropriately. Where possible, the tank room is located in the basement, which is warm in winter and cool in summer. During the pickling process, there should be a dedicated person responsible for frequent observation and inspection so that problems can be solved in a timely manner.
7. Coming out of the vat
The preserved eggs that are mature after inspection will be taken out of the vat. The soaking time is 30 to 40 days. Generally, when the temperature is low, the soaking time is longer; when the temperature is high, the soaking time is shorter. The eggshells will be fragile after soaking, so be careful when taking them out of the tank. Operators should wear rubber gloves to avoid burning fingers. After the preserved eggs are taken out of the vat, the dirt on the preserved egg shells should be rinsed with 1.5 to 1.8 caustic soda solution or the supernatant in which the preserved eggs have been soaked. If rinsed with cold boiled water, it should be wrapped with mud or waxed in time.
8. Quality inspection
Quality inspection must be carried out before coating the preserved eggs to remove broken, substandard and inferior eggs to ensure the quality of the preserved eggs. The inspection method is mainly sensory inspection, supplemented by light inspection. These methods are "one look, two weighs, three shakes, four flicks, five photos, and six peels".
(1) First inspection: Check whether the eggshell is complete and whether the shell color is normal, and remove damaged eggs, cracked eggs, black-shelled eggs and larger black-spotted eggs.
(2) Erwei: Weigh the eggs with your hands. Take an egg and put it in your hand, throw it up 5 to 20 centimeters, and throw it several times to determine whether its contents are elastic. If the egg is slightly elastic and heavy, it is a high-quality preserved egg; if it is elastic, it is a runny egg; if it has no elasticity, it is a watery preserved egg or a rotten egg.
(3) Three shakes: shake by hand. This method is a supplementary check for inelastic preserved eggs. The method is to pinch both ends of the preserved egg with your thumb and middle finger, shake it up and down, left and right by your ear two or three times, and listen for any sound of water. Those with no sound of water are considered good eggs, and those with the sound of water are called preserved eggs or rotten eggs.
(4) Four bombs: play with your fingers. Put the preserved egg in the palm of your left hand, and use the index finger of your right hand to gently flick the two ends of the egg. If it makes a soft "te" or "te" sound, it is a good egg. If it makes a stiff "de" or "de" sound The sound is bad.
(5) Wuzhao: that is, using light for perspective. When looking at the eggs, if most of the preserved eggs are black (dark green) and the small head of the eggs is yellow-brown or reddish, they are high-quality preserved eggs. If most or all of the egg is yellowish brown and moves slightly, it is an immature egg. If there is a black shadow inside the egg and there are blister shadows moving back and forth, it is a watery egg. If one end of the egg is dark red, it is a rotten egg.
(6) Peeling inspection: Take samples of preserved eggs and peel them for inspection. First, observe the shape, color, hardness, etc. Then use a knife to cut it lengthwise, observe the yolk, protein, and color inside, and finally taste it. If the egg white is smooth and clean, separated from the shell well, and appears as a tan or tea-green translucent body; the yolk is dark green or grass green, and the yolk center is an orange-yellow runny heart, with a fragrant smell and a delicious taste, then it is a high-quality preserved egg. If the egg white sticks to the shell, becomes rotten, or even becomes watery and liquefied, and more seriously, the egg yolk turns yellow-red and becomes hard, with a pungent, alkaline smell, the egg is alkali-damaged. If the egg white is solidified and soft, the yolk is runny and has a fishy smell, it means the preserved egg is not fully mature. If the egg white is well coagulated and the yolk is yellow, it is a preserved egg that has turned yellow due to exposure to air. Although this kind of preserved egg is edible, it lacks the unique flavor of preserved eggs.
9. Coating to preserve quality
(1) Coating with mud and chaff: The preserved eggs should be coated with mud and chaff in time after they come out of the vat. It has three functions: First, it protects eggshells from breakage, because after soaking fresh eggs, the eggshells become brittle and easily broken. Second, extend the shelf life to prevent preserved eggs from contacting the air or being contaminated by bacteria. Third, it promotes the post-cooking of preserved eggs and increases the hardness of the egg whites (especially the preserved eggs that come out of the vat early due to high temperature and are still soft and have a larger runny heart). To apply mud and wrap bran, you can use the egg-soaked liquid and add yellow mud to make a thick paste. You should wear rubber gloves when wrapping the mud. Each egg should be wrapped with 70 to 80 grams of mud, and the thickness of the mud should be 2 to 3 mm. After wrapping the mud, you need to stick a layer of chaff on the surface and wrap it with plastic film.
(2) Coating: Compared with coating with mud and wrapping bran, this method is hygienic, beautiful and convenient. This method was developed by the Animal Products Processing Research Team of the Animal Husbandry Institute of the Zhejiang Academy of Agricultural Sciences. Lead-free preserved egg cling film is used to wrap a piece of film on each preserved egg that comes out of the vat to preserve the quality.
10. Storage
There are generally three ways to store preserved eggs:
(1) Storage in the original vat: that is, extending the date of mature preserved eggs from the vat. If it continues to be stored in the original tank, it can generally be stored for 3 to 5 months without changing the quality.
(2) Packing and storage in a cylinder: Wrap the eggs with all the ingredients, seal and store them in a cylinder. The storage period can be up to about half a year.
(3) After packaging, pack the eggs into boxes or baskets for storage: wrap the eggs with all ingredients, put them in nylon bags instead of cylinders, pack them in cartons or bamboo baskets, and store them in the warehouse. The storage period can be up to 3 to 5 months, but when the temperature is high in summer, it is generally not necessary to store in cartons or bamboo baskets. It is best to store in cylinders.
The storage period of preserved eggs is also related to the season. Generally, the storage period is longer in spring and shorter in summer. Since preserved eggs are a flavored food, they should not be stored for too long. The temperature in the warehouse should be controlled within the range of 10 to 20°C, and the jars (tanks) and baskets (boxes) containing preserved eggs should be placed in a cool and ventilated place, away from the sun, rain or moisture. To avoid causing the preserved eggs to become moldy and spoilage.
11. Quality indicators of lead-free preserved eggs
(1) Sensory indicators
①Appearance: The mud layer and rice husk wrapping the mud eggs should be evenly thin and thick. Slightly moist, the coating on the paint egg should be even. Mud-coated eggs, painted eggs and bare eggs must not be moldy, and the eggshells must be clean and intact.
② Egg shape: The egg body is complete, shiny, elastic, with loose flowers, and does not stick to the shell. The soft-boiled preserved eggs have a generally soft or small soft core, while the hard-cooked preserved eggs have a hard core or a small hard core.
③ Egg color: The egg white is translucent greenish brown or brown, and the yolk is dark green with obvious multiple color layers.
④Smell and taste: It has the unique smell and taste of preserved eggs, no peculiar smell, not bitter, not astringent, not spicy, and has a long aftertaste. The hard preserved eggs are slightly spicy.
(2) Physical and chemical indicators
Moisture, 66～70
Total alkalinity, meq/100g 5～10
Arsenic ( Calculated as As), mg/kg ＜0.5
PH value (1/15 dilution) ＞9.5
(3) Bacterial index
Number of bacteria, Individuals/g <500
Escherichia coli, individuals/100g >30
Pathogenic bacteria (referring to Salmonella) shall not be detected