What are the new processing techniques for Acetes shrimp? A detailed explanation of the processing methods
Acetes shrimp, namely Acetes chinensis, also known as small white shrimp, water shrimp, etc., belongs to the class Crustacea, family Sergestidae. Its body is laterally compressed and its carapace is thin. The 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, with a rounded end, no spines, and the posterior half of the lateral margins and the terminal margin bearing feathery setae. The first three pairs of walking legs are in the form of tiny pincers, and the latter two pairs are completely degenerated. 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 inner ramus of the uropod with 3-8 red spots. It lives in shallow seas with muddy and sandy bottoms, mostly near bays or estuaries. Its swimming ability is relatively 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, and the eggs are semi-pelagic. The young shrimp grow very quickly. It is produced along the coasts of China, with the largest yield along the coast of the Bohai Sea. It is mostly caught with 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, which is slightly smaller in body size than Acetes chinensis, and the base of the inner ramus of its uropod has only one relatively large red spot. It is produced along the coasts of both northern and southern China and is caught with set nets; it is also an important economic shrimp species.
(1) Dried small shrimp
Dried small shrimp is a dried product made from Acetes shrimp, and there are two types: raw dried product and cooked dried product. The dried small shrimp produced from Acetes chinensis is of the best quality. The shrimp body is small and the shell is thin, so after drying it easily gives people the impression that it is merely a layer of skin, and 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. According to tests, 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 in dried small shrimp is the most notable among aquatic products, and appropriate consumption of dried small shrimp by children is greatly beneficial to their growth and development.
1. Cooked dried small shrimp
(1) Raw material handling: Before processing, Acetes shrimp 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 materials are fresh and free of sand, mud, and other impurities, they can be boiled directly. If there is sand, mud, or other impurities, they must be washed clean and picked out. A bamboo basket can be used for sieving and washing. The method is to first put 5-8 kg of shrimp in the basket, then place it in a large vat or wooden barrel containing clean seawater for washing. While washing, hold the edge of the basket with one hand and swing it left and right in the water, while gently turning the shrimp in the basket with the other hand so that sand and mud flow out through the basket holes and sink to the bottom, and at the same time pick out small miscellaneous 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 at 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 boiling, they can be taken out to drain. During the boiling process, the floating foam in the pot should be removed in time. Salt should be appropriately added each time a pot is boiled to maintain the concentration of the brine. After about 8 pots are boiled, when the broth has become very cloudy, it should be replaced immediately with new water.
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 deterioration of the semi-finished product. Special attention should be paid to this especially when processing on rainy days.
(3) Sun-drying: The boiled shrimp can be put out for drying only after sufficient draining and cooling. Before drying the shrimp, first shake the shrimp basket to loosen them, spread the shrimp evenly on a mat, and when dried to about 40% dryness, turn and rake them with a wooden rake. The turning should be even to avoid uneven drying, which can cause deterioration. In dry weather, they can be dried well in about half a day. When dried to about 60-70% dryness, gather them into a pile and store for two days, then put them out to dry again until about 90% dryness, and then they can be packaged. Properly controlling the dryness of dried small shrimp is a key issue. If too dry, they are easily broken and the taste is not savory; if too moist, they are prone to deterioration 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 crumbs. The packaging should be convenient for transportation and not easily broken, and moisture-proof material should be placed inside during packaging to prevent the dried small shrimp from absorbing moisture and deteriorating.
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 draining the cleaned fresh shrimp, spread them on a mat in a thin layer. When about 40% dry, turn them, and when dried to about 90% dryness, they can be stored. When processing raw shrimp, be sure to choose clear and dry weather; on cloudy days with higher humidity, the dried small shrimp are easily spoiled. 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 complete, and the dryness is appropriate (when you grab a handful with your hand and open your hand, the dried small shrimp can scatter automatically; when sprinkled on the floor, the dried small shrimp can bounce up), with no impurities, moderate saltiness, and a delicious taste.
(2) Quality of raw dried small shrimp: The color is white or light yellow, the shrimp grains are relatively large, neat and free of impurities, moderately dry, and when smelled they have the unique fresh fragrance of raw dried small shrimp.
4. Storage of dried small shrimp: Because dried small shrimp have a relatively high water content, they should not be stored for too long, especially in high-temperature seasons, when they are often prone to mold and deterioration after too long a time. For a short period, they can be sealed to prevent moisture absorption, and then they change relatively slowly. But for long-term preservation, they must be stored in a cold storage or refrigerator; otherwise, even if well sealed, they are still prone to mold and deterioration at room temperature during high-temperature seasons.
5. Methods of eating dried small shrimp: Dried small shrimp are most convenient to eat. Clean cooked dried small shrimp can be used directly in dishes, whether as soup dishes or cold dressed dishes. Dried small shrimp containing fine sand can be rinsed with cooled boiled water before eating. Raw dried small shrimp can only be used in cooked dishes, and it is best to rinse them with clean water before use.
(2) Shrimp paste and shrimp oil
Shrimp paste is a fermented product, usually made mostly from Acetes shrimp, mysid shrimp, Leptomysis 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 preliminary 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 will ferment and swell. 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 seasonings such as scallion, ginger, Sichuan pepper, and star anise, and simmer for about two hours. Remove the boiled seasonings, and this becomes delicious shrimp oil.
Some regions use a sealed fermentation method to process shrimp paste: 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, mix well, put into a jar, cover and seal (seal the jar lid with gypsum or mud), and keep at a temperature of about 30°C to ferment for about 3 months, and it becomes finished shrimp paste.
Coastal areas of southern China also use the following method to process shrimp paste and shrimp oil: after washing the raw materials 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. After maturity, take the upper liquid and filter it; the filtrate is simmered with seasoning spices to make shrimp oil, and the residue sunk at the bottom of the vat is ground to make shrimp paste.