How is Acetes processed? A detailed guide to Acetes processing technology
Acetes, namely Acetes chinensis, also known as small white shrimp, water shrimp, etc., belongs to the class Crustacea, family Sergestidae, with a laterally compressed body and a thin shell. Body length is generally 2.5-4 cm. The rostrum is short and small, roughly triangular in side view, with the lower margin oblique and slightly curved, and the upper margin bearing two teeth; the telson is very short, rounded at the end, without spines, and the posterior half of the lateral margins and the terminal margin bear feather-like setae. The first three pairs of walking legs are tiny chelate, and the posterior two pairs are completely degenerate. The body is colorless and transparent, with only the mouthparts and the second antennae flagellum red, the ventral surface of the sixth abdominal segment slightly red, and the base of the endopod of the uropod bearing 3-8 red spots. It lives in shallow seas with muddy and sandy bottoms, mostly near bays or estuaries. Its swimming ability is rather poor; it moves to deeper waters in winter and comes to nearshore areas to spawn after spring. The spawning period is long, from late May to late September; the eggs are semi-pelagic, and the young shrimp grow very quickly. It is produced along all the coasts of our country, with the largest yield along the Bohai coast. Fishing mostly uses stow nets. Besides being eaten fresh, it can also be processed into dried small shrimp, shrimp paste, shrimp oil, etc. A similar species is Acetes japonicus, slightly smaller in body size than Acetes chinensis, with only one relatively large red spot at the base of the endopod of the uropod. It is produced along both the northern and southern coasts of our country and is caught with set nets; it is also an important commercial shrimp species.
(1) Dried small shrimp
Dried small shrimp is the dried product of Acetes, and there are two types: raw dried product and cooked dried product. Dried small shrimp made from Acetes chinensis is superior. The shrimp body is small and the shell is thin, so after drying it easily gives the impression of being nothing but a layer of skin; the name "dried small shrimp" comes from this.
Dried small shrimp has high nutritional value and is a relatively inexpensive popular seafood product among aquatic products. Tests show that every 100 grams of dried small shrimp contains 39.3 grams of protein, 3 grams of fat, 8.6 grams of carbohydrates, 2000 milligrams of calcium, 1005 milligrams of phosphorus, 5.5 milligrams of iron, 0.03 milligrams of thiamine, 0.07 milligrams of riboflavin, and 2.5 milligrams of nicotinic acid. The calcium and phosphorus content of dried small shrimp is the most notable among aquatic products, and eating dried small shrimp appropriately is very beneficial to children's growth and development.
1. Cooked dried small shrimp
(1) Raw material handling: Before processing, Acetes must be graded according to freshness quality and processed separately, so as to avoid mixing good and bad together and lowering the quality of the finished product.
If the raw material is fresh and has no sand, mud, or other impurities, it can be boiled directly in water. If there is sand, mud, or other impurities, it must be washed clean and picked out. It can be sifted and washed in a bamboo basket; the method is to first put 5-8 kg of shrimp in the bamboo basket, then place it in a large vat or wooden barrel filled with clean seawater and wash it. While washing, hold the edge of the basket with one hand and swing it left and right in the water, and with the other hand gently turn the shrimp in the basket so that sand and mud flow out through the holes of the basket and sink to the bottom, and at the same time pick out small trash fish and other impurities; after washing clean, lift the basket out to drain.
(2) Boiling: Pour an appropriate amount of fresh water into the pot, add salt equal to 6% of the weight of the water, and after the water boils put the raw shrimp into the pot (the ratio of shrimp to water is 1:4); after it boils, it can be taken out to drain. During the boiling process, promptly remove the floating foam in the pot. Each time a pot is boiled, salt should be added appropriately to maintain the concentration of the brine. After about 8 pots are boiled, when the broth has become very cloudy, new water should be replaced immediately.
During draining and cooling, the shrimp basket must not be shaken; otherwise the shrimp bodies will loosen from one another, which will affect the draining effect and can accelerate spoilage of the semi-finished product. This is especially important to note when processing on rainy days.
(3) Sun-drying: After the boiled shrimp have been fully drained and cooled, they can be put out to dry. Before drying the shrimp, first shake the shrimp basket to loosen them, then spread the shrimp evenly on a mat. When they are about 40% dry, turn and rake them with a wooden rake; the turning must be even so as to avoid uneven drying and spoilage. In dry weather, they can be dried in about half a day. When they are 60-70% dry, gather them into a pile and store for two days, then put them out to dry until they are 90% dry, and they can be packaged. Properly controlling the dryness of the dried small shrimp is a key issue: too dry and they break easily, and the taste is not fresh and delicious; too moist and they easily spoil and cannot be stored for long. The yield is generally about 25%.
(4) Packaging: After the dried small shrimp are dried, they should be properly sieved to remove broken bits and powder. The packaging material should be convenient for transport and not easily broken, and moisture-proof material should be placed inside during packaging to prevent the dried small shrimp from absorbing moisture and spoiling.
2. Raw dried small shrimp: The raw material handling is basically the same as for cooked dried small shrimp, but the freshness requirement is high, and the shrimp bodies should be relatively large and uniform.
After the cleaned fresh shrimp are drained, spread them on a mat in a thin layer. When they are about 40% dry, turn them, and when they are 90% dry, they can be stored. When processing raw shrimp, be sure to choose clear and dry weather; on relatively humid cloudy days the dried small shrimp easily become stinky. The yield of raw dried small shrimp is generally about 20%.
3. Quality requirements for dried small shrimp:
(1) Quality of cooked dried small shrimp: The color is preferably yellow-white; the shrimp grains are uniform in size and intact; the dryness is appropriate (grab a handful with your hand, and after opening your hand the dried small shrimp can scatter on their own; when the dried small shrimp are sprinkled on the floor, they can bounce up); there are no impurities; the saltiness is moderate; and they have a fresh and delicious taste.
(2) Quality of raw dried small shrimp: The color is white or light yellow; the shrimp grains are relatively large; they are neat and free of impurities; the dryness is moderate; and they smell of the unique fresh aroma of raw dried small shrimp.
4. Storage of dried small shrimp: Because dried small shrimp have a relatively high water content, the storage time should not be too long. Especially in high-temperature seasons, if stored too long they tend to become moldy and spoil. For a short time, they can be sealed to prevent moisture absorption, and then they change relatively slowly. But for long-term storage, they must be kept in a cold storage or refrigerator; otherwise, even if well sealed, they easily become moldy and spoil at room temperature in high-temperature seasons.
5. How to eat dried small shrimp: Dried small shrimp are the most convenient to eat. Clean cooked dried small shrimp can be used directly in dishes, whether for soup dishes or cold dressed dishes. Dried small shrimp containing fine sand can be rinsed with cool boiled water before eating. Raw dried small shrimp can only be used in cooked dishes, and before use in dishes it is best to rinse them with clean water.
(2) Shrimp paste and shrimp oil
Shrimp paste is a fermented product, usually made from Acetes, mysid shrimp, biting midge shrimp, etc. First rinse the raw shrimp clean, remove impurities, drain, then mix in about 30% salt, put into a wooden barrel or vat to pickle. After 5-7 days the shrimp bodies have turned red, indicating initial fermentation. At this point the brine floating on top can be filtered off, then the shrimp bodies are mashed into paste, put into a vat or barrel, and after about 10 days of sun exposure the shrimp paste ferments and swells. After that, stir twice a day to make the fermentation uniform and thorough. After about one month, it ferments into finished shrimp paste.
The shrimp brine filtered out during shrimp paste processing can be processed into shrimp oil. The method is to place the shrimp brine in a vat and let it ferment in the sun; rainwater must absolutely be kept out. After about 3 months of high-temperature weather it can ferment well. After filtering, put it into a pot, add scallion, ginger, Sichuan pepper, star anise and other seasonings, and simmer for about two hours. Remove the boiled seasonings, and this becomes delicious shrimp oil.
In some areas, shrimp paste is processed by sealed fermentation: first add 15-17% salt to clean fresh shrimp and mix well; after 2-3 days of fermentation, add another 3-5% salt (total salt used not exceeding 25%), then grind the shrimp bodies into paste, and add 3% rice wine and 2-3% edible sugar; after mixing well, put into a jar and cover and seal it (seal the jar lid with gypsum or mud), and keep it at about 30°C to ferment for about 3 months, and it becomes finished shrimp paste.
In the southern coastal areas of our country, the following method is also used to process shrimp paste and shrimp oil: after the raw materials are washed clean, drain the water, put them into a large vat, add 30-35% salt and mix well, cover the vat, and place it in the open air to ferment for several months. When mature, take the upper liquid, filter it, and after adding seasoning spices and simmering, it becomes shrimp oil; the residue sunk at the bottom of the vat is ground and becomes shrimp paste.