Quality control of shrimp bran and squid paste

Liu Xingwang Wang Hualang  (Guangdong Hengxing Group Scientific Research Center, Zhanjiang 524094)   Abstract: this paper summarizes the quality control standards and adulteration status of shrimp bran and squid ointment, and puts forward the corresponding identification and detection methods. It has a certain guiding significance for the trade of feed raw materials and the management and control of feed quality. About the author of :  Liu Xingwang (1979 -): male, born in Jinan, Shandong Province, doctoral student, mainly engaged in aquatic animal nutrition research and aquatic feed development, Tel: 0759-2711372,  Email:xingwangliu@126.com  author correspondence address: Guangdong Zhanjiang Mazhang Economic Development Zone Jinkangzhong Road Guangdong Hengxing Group Co., Ltd. Scientific Research Center. 524094  shrimp bran and squid paste are important raw materials for aquatic feed. With the vigorous development of aquatic feed industry, the demand for shrimp bran and squid paste is also growing rapidly. However, both of them are made from the scraps of marine animals, so there are some problems, such as unstable quality, great differences in quality among different manufacturers and so on. And with the increase of demand, the problems such as adulteration are becoming more and more serious. Based on the author's practical experience, this paper talks about some problems such as quality control and adulteration identification of shrimp bran and squid paste.  1. Quality control and adulteration identification of shrimp bran  1.1Source and feeding value of shrimp bran  shrimp bran is a by-product of shrimp processing. The processing plants of prawn, lobster and oratosquilla in coastal areas of China can produce about 60, 000 tons of shrimp bran per year. The main ingredients are generally a mixture of shrimp shell and mixed shrimp, which can be divided into shrimp powder, shrimp shell powder, shrimp head powder, whole shrimp powder and so on. Shrimp bran is not only rich in chitin and protein, but also rich in DHA, EPA, choline, phospholipid, cholesterol, astaxanthin, astaxanthin and phosphorus, calcium, iron, manganese, zinc, copper and other beneficial elements. The protein, choline, phospholipid and cholesterol in  shrimp bran are mainly concentrated in the head cavity, chelate limbs and footsteps, which are indispensable substances for animals, which can improve animal fat metabolism and enhance immunity. EPA and DHA, which are rich in shrimp oil, can improve blood circulation and promote nervous function and reproductive system. Astaxanthin and astaxanthin can slow down the process of lipid peroxidation and prevent animal cells from being damaged by free radicals. they are natural non-toxic food pigments and have the effect of coloring animals. In addition, the rich active calcium in shrimp shell can be easily absorbed by livestock and poultry. Therefore, it can be said that shrimp bran is a kind of feed material with high usable value.  proved that shrimp bran has good feeding value in livestock, poultry and aquatic feed. Shrimp bran can improve the palatability of feed and contribute to the color formation of shank of broiler and egg yolk of laying hens. It can promote the appetite of pigs, and adding 30.5% to fattening pigs can significantly improve the meat color. Shrimp bran is the most commonly used food attractant and colorant with the most suitable price in fish and shrimp feed. 5% of shrimp bran is added to shrimp feed, which has a good effect of attracting food, promoting growth and improving body color. It also contains a molting hormone, which can effectively promote crustacean molting.  1.2 the quality index of shrimp bran  the raw material source of shrimp bran is uncertain, the quantity changes greatly, and its quality composition varies greatly with the difference of raw material, variety, treatment method and freshness. Therefore, how to control the quality of shrimp bran, improve the feeding value of shrimp bran and improve the processing technology is an urgent problem to be solved. The nutritional composition of  shrimp bran varies greatly by many factors, and it is often impregnated with salt for anticorrosion, so it contains more salt. Generally speaking, if the salt content is more than 7%, it is best not to be used in formula feed. Therefore, each ingredient must be detected in detail before it can be used in formula calculation. The moisture content of good quality shrimp bran should be less than 12%, crude fat less than 10%, hydrochloric acid insoluble matter less than 3%, salt less than 7%, crude protein and crude ash content vary greatly with different processing technology, the general crude protein content is about 30%, the crude ash content should be less than 42%. The general nutritional composition of shrimp bran with different composition can be seen in Table 1.  Table 1 nutritional composition of shrimp bran raw materials  Shrimp Shell Powder (CNS) Shrimp Shell Powder Shrimp Powder (Shrimp Shell + Miscellaneous Shrimp) Shrimp head Powder whole Shrimp Powder  moisture content 12.07.53.2--  crude protein%-- 24.9 37.2 58.2 73.6  crude fat% 2.5 below 2.6 5.3 8.9 6.3  Crude fiber%-13.6 21.4 11.9- crude ash% 42 below 39.4 38.2 22.6 18.6  calcium%-12.9 15.0-- 3.0  phosphorus%-1.42.2-- 1.1  total nitrogen% below 4.02-5.97 9.32- salt% less than 7.0 - hydrochloric acid insoluble matter less than 3.0%- The physical and chemical items that need to be tested after the arrival of shrimp bran include moisture, sand, salt, ash, crude protein, crude fat, calcium and phosphorus content and so on. Due to the great changes in protein, fat, ash, etc., it is necessary for quality inspectors to determine the standards of these indicators according to the requirements of the formula. Special attention should be paid to the moisture, sand and salt content of shrimp bran. If it exceeds the control standard, it should be deducted, discounted or returned according to a certain standard.  in addition, because the production of shrimp bran is generally dried by the sun, it is easy to contaminate bacteria, decay and oxidation. Therefore, before use, we need to test volatile base nitrogen to judge its freshness, in addition, we also need to detect the total number of bacteria, intestinal pathogenic bacteria salmonella and other microbial indicators. The qualified standard is that the volatile basic nitrogen is less than 0.3 mg, the pH is less than 7.8, and the total number of bacteria is less than 1 × 107 / g, salmonella can not be detected. If in-depth testing is necessary, arsenic, mercury, peroxide value, nitrite and other items can also be detected. General feed enterprises do not have bacteria and other microbial detection conditions, so bacteria, heavy metals and other detection items can be detected and controlled by sending samples on a regular basis.  is worth mentioning here that part of the protein in shrimp bran crude protein comes from chitin nitrogen; the chitin content of shrimp powder is very close to that of crude fiber, which is not only in the carapace, but also in the inner layer of gastric wall, so it has no use value. Therefore, when calculating the formula, the non-protein nitrogen from chitin should be removed before it is a real protein. Chitin content detection is not easy, can be calculated by rough estimation, shrimp shell powder, for example, contains about 35% crude protein, nitrogen shrimp shell contains about 50% chitin, of which inorganic nitrogen accounts for about 7%. Therefore, the protein content from non-protein nitrogen is about 21.9% (50 × 7% × 6.25), then the real protein content should be 13.1%. Appearance detection and adulteration identification of  shrimp bran  shrimp bran should first be spread on a white disk for appearance inspection to check whether the smell is normal, whether there is obvious spoilage ammonia smell and impurities. Shrimp shell powder is crisp and fragile, mostly flaky, containing black shrimp eye fragments. Shrimp shell varies according to the color of shrimp pigment, from light yellow, pink to orange. There is a distinct smell of dried shrimp.  observed under the microscope that there are horizontal lines, cross lines and other marks caused by parasites on the shrimp shell. The hairs on the shrimp legs are short, rarely branched, and the tips do not have small hooks like feathers. The segment of shrimp antennae can be seen under stereoscopic microscope, which is in the shape of a long tube with spiral parallel lines. Shrimp eyes are compound eyes, appear to be small wrinkled pieces, dark purple or black, with shadow lines on the surface. Shrimp meat of different sizes, glossy, translucent, yellow, orange or pink, sometimes hard texture, or muscle fibers are easy to break into small pieces, the continuous shell from the shrimp body is thin and transparent, while the head shell is quite thick, opaque, shrimp leg fragments are wide tubular. Hairy or no hair, flat and shiny, translucent. On the one hand, the dopants of  shrimp bran come from non-feed substances such as quicklime and wood bran for anticorrosion and water absorption in the processing process. On the other hand, it is purely for the purpose of profiteering, the illegal addition of ammonium salt, urea, stone powder, shell powder, sediment, dyes and other toxic and harmful substances. Generally can take the following methods for identification:  hydrochloric acid dissolution identification method: put a small number of samples on the white porcelain plate, add 8-10 to extract 1:3 hydrochloric acid, if there are bubbles show that mixed with quicklime, stone powder, shell powder and other carbonate substances.  washing identification method: add water to the 200ml beaker about 150ml, take about 5 grams of the sample slowly withdraw to the surface of the water to observe, sediment faster than the sample to settle into the bottom of the arms, and then carefully rinse the sediment with water to see the sand and gravel. Another 10g sample was placed in a l00ml high beaker, mixed with 80ml carbon tetrachloride and placed for 1 minute. The upper float was filtered, dried and screened, and the sediment was filtered and dried. Most of the powdered plants were left on the 10-20 mesh sieve surface. The washing suspension method can also observe whether the solution has color to determine whether it is mixed with dyes and other substances.  lignin qualitative method: take a small amount of samples on a white porcelain plate, wet the samples with phloroglucinol (5% ethanol solution), drip hydrochloric acid 2 minutes later, show dark red to prove that plant substances such as wood bran are mixed.  urea qualitative method: take a small number of samples on the white porcelain plate, add 2-3 drop cresol red (0.1% aqueous solution) and 2-3 drop urease (0.4% aqueous solution), 5 minutes later, if there is fuchsia, it indicates that urea is mixed.  ammonium salt qualitative method: take a small number of samples into the test tube, add about 5ml water and shake well, and then add a few drops of dilute hydrochloric acid and 10% barium chloride solution at 1:3. If there is white precipitation, ammonium sulfate is added. In addition, a small amount of samples were placed on the white porcelain plate, adding 3 diphenylamine grains and 2 dripping water, and then adding l dripping sulfuric acid, which showed dark blue, which indicated that ammonium nitrate was added.  in a word, shrimp bran inspection is a complex and changeable process, and microscope examination is intuitive and clear, but it requires high technology and rich experience. Although qualitative identification is simple and fast, it can only indirectly indicate the existence of a substance, and it is difficult to determine the quantity. Health index is a prerequisite to judge whether the product is good or bad and whether it can be used as livestock and poultry feed. Physical and chemical inspection is not only an indispensable step in formula calculation, but also a reliable basis for judging product quality. The vast number of raw material procurement personnel and quality inspection staff should fully understand and master these methods, and continue to learn and communicate with each other in order to minimize the damage caused by fake and shoddy raw materials and reduce unnecessary losses.  2. Quality control and adulteration identification of squid ointment  2.1.The source and feeding value of squid ointment  squid ointment is a kind of paste made from squid viscera and processed by refinement, filtration, sterilization and drying. It is an excellent food attractant and nutritional supplement in aquatic products, livestock and poultry feed.  experiments have proved that adding squid ointment to aquatic feed can obviously induce fish and shrimp, and can improve the palatability and utilization rate of the feed. This is because the squid paste has a good composition of amino acids, which has a very strong attractive effect on fish and shrimp, and contains highly unsaturated fatty acids and cholesterol, which is an indispensable nutritional element to promote the digestion, absorption and growth of shrimp and crab. At the same time, squid ointment is rich in sterol shelling hormones and other unknown nutritional factors, which can effectively promote crustacean shelling and improve the immunity of aquatic animals. In addition, the appropriate addition of squid ointment to the pellet feed has an auxiliary bonding effect on the granulation of the pellet feed, which can improve the granulation efficiency and reduce the wear of the ring die roller. Therefore, squid ointment is widely used in aquatic feed, and the market demand is increasing year after year.  2.2quality index and control of cuttlefish ointment  squid ointment is black or brown in color and has a strong cuttlefish fishy flavor, usually in buckets. Therefore, the quality inspection of squid cream must be sampled in the middle of the barrel.  cuttlefish and other internal organs because of the high water content, mostly more than 75%, after processing and drying, the water content in squid cream is still very high, the general water content is about 35%. Too high moisture content can easily lead to rancidity and other problems of raw materials, and affect the control of moisture in the production process, and improve the production cost. Therefore, when purchasing squid cream, feed enterprises should negotiate with the production enterprises to reduce the moisture content in the products as much as possible, and it is appropriate to control the moisture content below 30%. The protein content of  cuttlefish cream varies with its water content, which is generally required to be more than 30%. It should be pointed out that the content of amino acids in squid cream is very balanced, in which lysine, methionine, histidine and other essential amino acids are very rich and reasonable, so it is a high-quality protein source. Qualified enterprises should determine the amino acid composition of squid cream, which is the most effective way to control its quality. The fat content of cuttlefish ointment varies greatly due to different processing and treatment methods of . The fat of squid ointment is rich in a variety of essential fatty acids, such as EPA, DHA, etc., which is necessary for animal growth and can improve animal immunity. Many aquatic products processing enterprises treat and extract the oil from squid paste to make squid oil, which has high economic value. Therefore, squid ointment must test its fat content after entering feed enterprises, and the fat content of high-quality squid ointment should be controlled at about 20%. If it is too low, it means that there is loss in the processing; if it is too high, it will affect other nutritional indicators such as protein.  cuttlefish ointment must strictly abide by the Safety and Health Management measures for Animal-derived Feed products in all aspects of processing, transportation and storage. In order to control its quality, processing and feed enterprises should regularly or batch test the total number of bacteria, Escherichia coli, salmonella, heavy metals, specific pathogens and other safety and health indicators, only after the compound national standards, can be purchased or used. In addition, squid ointment is easy to deteriorate in the process of storage and transportation, so its volatile base nitrogen and acid value must be detected regularly. The qualified standard is that the volatile basic nitrogen is less than 4mg/g and the acid value is less than 40mgKOH/g.  is difficult to identify if adulterated because the physical properties of cuttlefish ointment are paste-like. Therefore, feed enterprises should choose excellent and honest suppliers and manufacturers to buy. Generally common doping is mixed with sea sand, salt, etc., therefore, the ash and salt content of cuttlefish paste must be determined after arrival, the salt content is generally controlled below 10%, and the salt content should be controlled below 7%. In addition, the determination of amino acid composition of squid ointment by high performance liquid chromatography is the most effective method to control its quality.  2.3squid powder  squid powder (or squid viscera powder) is a product made by aquatic products processing enterprises that separate squid ointment or oil from squid head, feet, offal, etc., mixed with soybean meal and fish solution, and then dried and crushed, with the characteristics of simple addition and low moisture, it plays the same role as squid paste in feed, and is often used by feed enterprises. However, its quality is also very difficult to control due to the difference in the quality of squid paste and the mixing ratio of squid paste and soybean meal. And many unscrupulous manufacturers mix deteriorated squid cream with rapeseed meal, wheat bran and other substances, seriously damaging the quality of this raw material, resulting in its poor utilization. At present, most feed enterprises do not have an effective way to control its quality, so it can be used as a supplement to squid ointment, but its use should be controlled as far as possible.  reference:  Qin Yi. A simple method was used to identify whether the feed was adulterated or not. Modern Fisheries Information, 2003, 18 (1), 32-32.  Wang Youming. Some experience in preventing adulteration of feed raw materials. Feed wide angle, 2002 (12), 19-19.  Peng Jinrui. Some thoughts on the problem of feed adulteration. Feed wide angle, 2001 (13), 9-10.  Nie Qingping. Talking about the utilization and inspection of shrimp bran. Guangdong Feed, 1996 (1), 42-43. -Thank you for sharing, good information-good information, thank you for sharing. -I'm glad to see this article here! Dr. Liu is so talented! The article is of great reference value!-good information, thank you for sharing, thank you.-not bad! Thank you!-I have different views on the quality index of squid ointment in this article.-good, good. -these two things have not been used yet, but it is necessary to learn.-those who have different views should share their views with the public and look forward to it. -Thank you for sharing. Study first.-Thank you for your hard work.