Livestock (bovine, pig, and sheep) blood is a resource that can be processed into a variety of products using livestock blood as a raw material. In a few remote areas of our country, due to the lack of awareness of the blood processing and utilization of livestock, coupled with limited geographical conditions and lack of technology, the blood of livestock is mistakenly regarded as a “burdenâ€, and individual areas even arbitrarily discard the blood of livestock, resulting in local Environmental pollution that should not occur.
Statistics show that livestock blood accounts for about 8%-9% of the livelihood of livestock, and the blood yield is 3%-5% of the livelihood of the livestock, of which bovine blood is 5% of the live weight, and pig blood is lively. 3.5%, sheep blood is 3.2% of live weight. Nationally, the blood of livestock that can be used for processing is a huge number. It goes without saying that the processing and utilization of livestock blood, the value of livestock blood, and the potential effectiveness and use of livestock blood are undoubtedly a cause of creating wealth, enriching the environment, and benefiting the country and the people.
1 The nature of livestock blood
The blood that has just flowed out of the animal is a red, opaque, slightly alkaline liquid with a slightly sticky, salty or special smell. When the blood of a livestock comes out from a blood vessel or a bloodletting mouth, it is a liquid. If it is left still, it will become sticky after about 5-10 minutes, and it will form a red jelly. The blood forms filamentous fibers in a liquid state, which is formed into a network and filled with liquid. At this time, the blood has lost the characteristics of the liquid and condensed into a block shape. This phenomenon is commonly called coagulation. Blood coagulation is a process in which plasma changes from a sol to a gel.
Livestock blood is weakly alkaline, pH 7.3-7.5. Generally, the pH of blood refers to the pH of plasma, and the pH of blood cells is about 7.1. The blood itself has a buffering effect, and the pH can be maintained at around 7.4 even if carbonic acid is continuously increased.
The specific gravity of livestock blood is in the range of 1.041-1.057, usually between 1.05-1.06. The specific gravity of blood is roughly proportional to the amount of protein in the blood.
The viscosity of blood is mainly derived from blood cells, and the viscosity of plasma and hemolysis is very low. The ratio of water, plasma, and whole blood viscosity is 1:1.7-2.0:3.6-5.4.
2 Composition of livestock blood
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Livestock blood consists of a portion of the liquid plasma and a formed hematopoietic cell suspended in the liquid. In the blood of livestock, dry matter accounts for 18%-23%, and the rest is water. Among the dry matter, organic compounds account for 17%-22%, and inorganic compounds account for 0.6%-1%. Plasma accounts for about 60% of blood and blood cells account for about 40%. The water content in plasma is 90%-92%, and the dry matter is 8%-10%. The dry matter in plasma is mainly composed of proteins and salts (see Table 1). Plasma proteins include albumin, globulin, and fibrinogen, accounting for 6%-8% of total plasma. Fibrinogen plays an important role in blood coagulation.
The plasma also contains some inorganic salts, which are relatively constant under normal conditions, accounting for about 0.9%. In addition, plasma contains a small amount of hormones, enzymes, vitamins and antibodies.
Blood cells include red blood cells, white blood cells, and platelets. Red blood cells are the main component of the blood. They are red and round spheres. The red blood cells account for about 60% of the water and the dry matter accounts for about 40%. The main dry matter is hemoglobin, which accounts for 90%, and the remaining 10% is other proteins, lipidoids, glucose and inorganic salts.
White blood cells are colorless, nucleated spheres that are larger than red blood cells and much less numerous than red blood cells. White blood cells contain components of common cells such as proteins, nuclear proteins, lipids, lecithin, cholesterol, enzymes and inorganic salts, and there are quite a few proteases.
Platelets are small, non-nuclear, irregular shaped bodies whose primary function is to participate in the blood coagulation process.
3 Animal blood collection, anti-coagulation and preservation
3.1 Collection of livestock blood
Regardless of the manufacture of any blood product, the collected blood must be protected from contamination. When collecting livestock blood, it should be carried out according to its application requirements. Blood used as edible and medical products is more hygienic and more demanding than the blood used as an industrial product, requiring special tools and utensils. In particular, it should be emphasized that the blood of livestock used as food, medical, and feed additives must be derived from livestock that have been confirmed to be healthy after quarantine.
The container for collecting blood of livestock varies with processing purposes, such as processing plastic powder for plastic containers; if blood is to be coagulated, the storage container may be in the shape of a barrel or a box; defibrinated blood or blood added with anticoagulant should be Stored in milk tank-type containers, which are ideal for stainless steel containers.
In order to prevent livestock blood from decaying, the collected blood should be transported to the processing plant as soon as possible. Livestock blood must be transported in a sealed container, one to prevent seepage and the other to prevent contamination.
3.2 Anticoagulation of livestock blood
Thrombin in the blood of livestock makes the plasma-dissolved protein, fibrin, a linear insoluble fibrin. These threads form a net, and the molded product in the entangled plasma becomes a clot. Many blood products must have a liquid requirement for the raw animal blood. That is to say, blood that needs to be defibrated is required. Therefore, preventing blood coagulation has become a problem that must be solved.
In order to prevent blood from clotting and maintain the fluid state of the blood, two methods are usually used:
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(1) Add anticoagulant to the blood of livestock
Commonly used anticoagulants are oxalate, sodium citrate, ethylenediaminetetraacetic acid (EDTA), and heparin. Oxalate is banned because oxalate is toxic, when processing blood products or when making medical blood products. The use of oxalate, sodium citrate, EDTA, and heparin should be used in strict accordance with relevant national regulations and regulations.
The anticoagulant is preferably stored as a solid salt and formulated as a solution prior to use. Some anticoagulant solutions are toxic, especially heparin, and should never be in contact with food. Safety issues must not be taken lightly.
(2) Removal of blood fibrin by agitation
The stirring method is to remove fibrin by a blood agitating defibration machine, and to remove fibrin by an artificial method. The artificial method is to use a rough-surfaced wooden stick or a long-handled brush to constantly stir the blood in the container, the fibrin is destroyed, one part is attached to the stick or the brush, and the other part is floating in the blood. On the surface (the specific gravity of fibrin is 0.8 and the specific gravity of the blood is 1.055), fibrin can be separated from liquid blood. When the defibrinated blood is poured into another container, the fibrin is leached by filtration. The blood that has been defibrated retains its liquid properties.
When artificially agitating defibrin, about 12% of blood fibrin can be obtained from blood, which can be used as processing feed, fertilizer and other blood products.
3.3 Preservation of livestock blood
Livestock blood is rich in nutrients and is the best medium for bacterial growth. When the blood is exposed to the air for a longer period of time, the amount of bacteria will quickly multiply. When the blood is spoiled, an unpleasant smell is produced, which is due to the decomposition of blood proteins by bacteria.
The so-called preservation of livestock blood is to try to prevent the proliferation of bacteria and the decomposition of blood proteins themselves. The preservation of livestock blood can be carried out by methods such as dry storage, refrigeration and chemical preservation. Dry preservation is to dry the blood of the livestock into a blood meal, and the blood of the blood is dried. The chemical composition and protein remain unchanged.
In the northwest and northeastern regions of China where the temperature is very low in winter, frozen methods can be used to preserve blood. The freezing point of the blood is 0.56 °C. When the blood freezes, the bacteria also stop moving. The frozen blood is remelted to form a blood meal, and its chemical composition and protein remain unchanged. For the blood of livestock for consumption, 10% of fine salt is added to the blood of defibrin, stirred evenly, and placed in a refrigerator at 5-6 ° C for about 15 days.
Chemical preservation is the use of chemical agents to prevent or inhibit the growth of bacteria in the blood of livestock, without decomposing the albumin of the blood. But most of these chemicals are harmful to the human body, so that the blood can not be used for food. Therefore, the chemical preservation method is not suitable for preservation of blood of livestock for medical, forage, and edible blood products. The chemical commonly used in chemical preservation methods is crystalline carbolic acid.
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4 Preparation of livestock blood products
With the development of China's collectivized aquaculture industry and the formation of mechanized slaughtering mode, China's livestock blood resources are increasingly rich. Livestock blood is rich in protein and can be processed into a variety of blood products, widely used in food, medicine, light industry, feed industry.
4.1 plasma
Plasma contains protein and various salts. It is a nutrient-rich full-price protein and a good food additive. Taking pig plasma as an example, it can be added to western-style cakes, Chinese cakes, biscuits, noodles, soy protein meat, meals, and other foods and dishes. Adding to the sausage can act as an emulsification to make the product retain water and elasticity. When added to the bread, it can enhance the color of the bread, ensure the product's shape retention and extend the shelf life.
The plasma is separated and prepared from the blood, the equipment investment is small, and the process technology is simple. The main equipment for preparing plasma is a milk separator. The plasma and blood cells that make up the blood have a specific gravity of 1.024 and 1.09, respectively. In a centrifuge that rotates at a high speed, a large blood cell is rapidly flowed into the periphery of the separation body due to a large centrifugal force, and then flows out along the outer wall; the plasma portion having a small specific gravity is gradually collected in the middle circular hole of the separation body. The corpus callosum is removed through the upper hole to achieve the purpose of separation.
When preparing plasma, to ensure the separation effect, the control temperature should not be lower than 18-26 °C, and the speed of the separator should not be lower than 6000r/min. The blood flow into the separator is controlled so that the quality of the prepared plasma can be guaranteed. Since plasma is used for food, the blood of livestock used as plasma preparation must be blood that is confirmed to be healthy livestock after quarantine.
4.2 Charcoal
Blood charcoal is used as a decolorizing and deodorizing agent in the light and chemical industries, and is used in the sugar, wine and pharmaceutical industries.
Brief description of the production process of blood charcoal: the tangible material after separating the plasma is added with potassium carbonate (the ratio is 8:1), stirred, heated and retorted, and then cooled and cooled. The potassium carbonate is recovered by warm water washing, and finally rinsed with dilute hydrochloric acid, and then washed with warm water until neutral. Drying (below 120 ° C), grinding into powder, that is, the finished blood charcoal.
4.3 blood meal
Blood powder can be divided into feed blood powder and industrial blood powder according to different purposes.
4.3.1 Feed blood meal
Feed blood meal is a product made by drying and pulverizing the blood of coagulated livestock. The process is not complicated, the technology is easy to master, and it is suitable for large-scale centralized production and suitable for simple equipment dispersion processing.
Blood meal is a good source of animal protein and essential amino acids in compound feed. Its crude protein content is higher than that of fish meal, meat powder, tryptophan and lysine, and even exceeds fishmeal. In addition, blood meal also contains a variety of vitamins and trace elements. According to the measurement, the crude protein in blood meal has a digestibility of 87% for chicken and a crude fat digestibility of 90%. Feeding chicken with blood meal, the utilization rate of lysine is higher than that of fish meal and soybean cake. Feed blood meal is used for animal protein supplements in chickens and pigs. The feed amount is generally 5% of compound feed and 3% for chicks.
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A process
Fresh livestock blood → collection → boiled blood → press dehydration → drying → crushing → inspection → packaging.
B process description
(1) When collecting blood from fresh livestock, add the crushed quicklime powder to about 1% of the whole blood volume, and stir it before blood coagulation to distribute the quicklime evenly into the blood.
(2) When boiled blood, stir while heating until a crisp clot is formed.
(3) After dehydration by pressing, the water content of the cooked blood should be below 50%.
(4) When drying, the hot air temperature should not exceed 60 °C, and it can be dried on the drying field in areas with strong sunshine.
(5) The moisture content of the finished blood meal cannot exceed 8%, otherwise it is difficult to store. The packaged blood meal should be stored in a cool, dry place. The blood powder with lime powder can be stored for one year when collecting blood, and the blood powder without lime powder can only be stored for one month.
4.3.2. Industrial blood meal
Industrial blood meal, also known as spray-dried blood or black blood protein, is a deep reddish brown powder with a water content of 5%-8%, ash 10%-15%, soluble in water.
Industrial blood meal is widely used as a binder in the plywood industry, as a protein polishing agent in the leather industry, as a stabilizer in asphalt latex, as a foam stabilizer in ceramics and as a catalyst for decomposing hydrogen peroxide. It can be used as a stabilizer, a diffusing agent and an adhesive for insecticides and fungicides.
A process
Defibrinated blood → filtration → spray drying → cooling → packaging.
B process description
(1) The raw material blood of the blood powder for processing industry is defibrinated blood, and the prepared defibrinated blood should be processed within a few hours. If it cannot be processed temporarily, it must be stored at 4 °C.
(2) Filtration is to remove fibrin and impurities and provide a qualified raw material for spray drying.
(3) The packaging usually uses a polyethylene bag, which is convenient for storage and can be stored for up to 5 years.
C blood meal quality standard
(1) Physical indicators
Shape: Fine powder passing through a 2mm sieve. Blood powder and aqueous solution smell: no special rancid smell. Color: reddish brown with minimal differences. Concentration of glue: black jelly with red luster.
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(2) Chemical composition index
The chemical composition indicators are shown in Table 2.
4.4 blood foaming agent
The foaming agent obtained from the defibrinated animal blood is a brown transparent liquid which, upon agitation, produces a foam. Foaming agent is the raw material for making foam concrete. The foam concrete body is light and weighs only 30 kg per cubic meter and can be used for cold storage insulation.
A production process
Defibrinated livestock blood → heating alkalization → acid neutralization → filtration → finished product.
B process description
(1) Heating to 90 ° C, the added alkali is a caustic soda solution, after adding alkali, at 90 ° C for 3 h, the heating is stopped.
(2) When the temperature was lowered to 60 ° C, hydrochloric acid was added and neutralized to pH 7.0.
(3) The precipitate is filtered off to obtain a brown transparent liquid foaming agent.
When making foam concrete from blood foaming agents, ferrous sulfate should be added as a foam stabilizer (addition amount is 5% of the foaming dose). Foamed concrete can be made by mechanically stirring it into a foam and then pouring it into the cement.
4.5 blood casein
Blood casein is a dark brown black powder or granulated product made from defibrinated plasma by acid addition, pressing and drying. Blood casein can be used as a plastic glue, can be made into a variety of plastic materials, making a variety of electrical parts, container handles, and a variety of button materials.
Brief description of the production process of blood casein: The metered defibrotated plasma is injected into an acid-resistant cylinder and stirred by hand or machine. During the stirring process, the concentration of 20% nitric acid was slowly added, and stirring was continued for 1 hour, and stirred for 3-5 minutes every 30 minutes in the next 6 hours. After the blood casein is precipitated in the solution, it is then placed in a cloth bag to filter off some of the water, placed on a bamboo mat or bamboo pole, and dried in the sun. If it is dried in a drying chamber, the temperature is controlled at 45-50 ° C, and it needs to be flipped frequently to make it dry.
The yield of blood casein is about 22% of defibrinated plasma.
4.6 heme
Heme is also called high erythropoietin and hydroxyheme. Heme is a blue to brownish black powder crystal. It was heated to 200 ° C without decomposition and decomposition. Soluble in sodium hydroxide alkaline solution and hot alcohol, slightly soluble in hot pyridine, insoluble in water, ether and ammonia.
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Heme is a compound called protoporphyrin composed of protoporphyrin and a divalent iron atom, and has high practical value. In the pharmaceutical industry, heme can be used as a semi-synthetic bilirubin raw material and is the main raw material for the preparation of an anticancer drug, a hematoporphyrin derivative. Heme itself is an important drug, which is used clinically for lead poisoning. It can also be used as a supplemental iron to treat anemia caused by iron deficiency. In the food industry, hemoglobin can replace the coloring agent nitrite and synthetic pigment in meat products. It uses meat products to create an attractive bright red color that adds to its aesthetic appeal. For example, if hemoglobin is added to Western-style ham and red sausage products, the cut surface of the product is uniform in color, bright and beautiful, maintaining the inherent natural color of the muscle, the tissue is fine and free of vacuoles, the taste is strong, the taste is pure, and the nutritional value is increased. More importantly, the use of heme instead of nitrate can avoid the carcinogenic effects of nitrite.
There are many methods for producing heme, and the commonly used methods are sodium acetate method, citric acid method, glacial acetic acid method, distillation method, and carboxymethyl cellulose method.
4.6.1 sodium acetate method
A process
Fresh livestock blood → separation → hemolysis → filtration → static precipitation → filtration → drying → product.
B process description
(1) Add trisodium citrate (0.8% of the blood) to the blood of fresh livestock and mix well. Then, put it into the centrifuge tube, centrifuge at 3000r/min for 15min, and discard the clear solution (available for preparation). Thrombin used).
(2) Blood cells were collected, and an equal amount of distilled water was added thereto, and the mixture was stirred for 30 minutes to hemolyze the blood cells, and then 5 times the amount of chloroform was added to filter out the fibers.
(3) Add 4-5 volumes of acetone solution (containing acetone volume 3% hydrochloric acid) to the filtrate, calibrate the pH to 2-3 with 1 mol/L hydrochloric acid, stir and extract for about 10 minutes, then filter, and filter residue is dried. The protein powder is obtained, and the filtrate is collected and used.
(4) In the collected filtrate, adjust the pH to 4-6 with 1 mol of sodium hydroxide, then add 1% sodium acetate to the filtrate, stir evenly, and let stand, and the hemoglobin precipitates in amorphous black green. After filtration, That is, a heme precipitate is obtained.
(5) The heme precipitate is dried and the hemoglobin product is obtained.
4.6.2 Glacial acetic acid method
A process
Fresh livestock blood → extraction → standing sedimentation → washing → drying → crude hemoglobin.
B process description
(1) Put four times the volume of glacial acetic acid in the blood of the livestock into a sealed extraction tank, then add fresh livestock blood, heat at 90 ° C, stir for 30 min, and let stand for about 10 h, that is, precipitates with bright crystals are precipitated.
(2) The precipitate is filtered off, and the precipitate is washed with 50% acetic acid solution, distilled water, ethanol, diethyl ether, washed, and dried to obtain crude hemoglobin. After being sealed and packaged, it can be sold to pharmaceutical factories and biochemical pharmaceutical plants as raw materials.
The glacial acetic acid method is used to prepare crude heme, which has low investment and simple process, and is suitable for small town enterprises and professional households.
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4.7 Hydrolyzed protein
With the continuous improvement of people's living standards, higher requirements are put forward for cosmetics, which not only requires beautification, but also requires nutrition and curative effect. Hydrolyzed protein moisturizes the skin, delays the skin aging process, promotes cell metabolism, enhances skin elasticity and hair shine, and reduces the effects of pigmentation and wrinkles on the skin surface. A brief introduction will be made to the production process of hydrolyzed protein for cosmetics by enzymatic hydrolysis using livestock blood as raw material.
A process
Fresh livestock blood → fibrin → rinse → minced → boiled → enzymatic hydrolysis → filtration → bleaching → filtration → concentration → drying → finished product.
B process description
(1) The collected fresh animal blood is continuously stirred rapidly to separate the fibrin, and then the fibrin is filtered out.
(2) Repeated rinsing with water until the blood fiber has no obvious blood color, and it is white.
(3) The fibrin is broken into a blood sludge by a meat grinder.
(4) Add a certain amount of blood sludge to the reaction tank, and add 5 times the amount of water to boil for 30 minutes. After the temperature is slightly lowered, the upper liquid is aspirated. Add the same water as before, and adjust the pH to 9.0 with 10% caustic soda solution, boil for 30 min. After the temperature is slightly lowered, the upper liquid is aspirated, the same water is added for the previous time, boiled for 30 min, and then the temperature is lowered.
(5) When the temperature of the reaction tank is lowered to 55 ° C, an appropriate amount of toluene is added, and the porcine pancreatic juice is slowly added under stirring, and the amount is 15%-20% of the amount of blood sludge. The pH was adjusted with saturated lime water to stabilize it between 7.2 and 7.5. Stirring was stopped after 5 h of hydrolysis. The hydrolysis time was 20 h, and the whole hydrolysis process was stable at about 50 °C.
(6) After completion of the hydrolysis, the pH was adjusted to 6.5-7.0 with 3:10 (i.e., 3 parts of phosphoric acid, 10 parts of water) to terminate the enzymatic reaction. Heat and boil for about 20 minutes, and filter to obtain a neutralizing solution.
(7) In the boiled neutralization liquid, add activated carbon for sugar, heat to 80 ° C, stir and keep for 40-50 min, filter and recover activated carbon, adjust the pH of the filtrate with phosphoric acid to about 6.5, and separate the supernatant with a centrifuge. .
(8) After the supernatant is concentrated, vacuum drying is carried out at a low temperature to obtain a product.
4.8 blood tofu, blood sausage
The livestock blood is rich in nutrients, high in protein content, complete in essential amino acids, rich in trace elements, and has high nutritional value. It can be processed into blood tofu, blood sausage and other human consumption. Animal blood that produces blood tofu and blood sausage must be derived from livestock that have been confirmed to be healthy after quarantine.
4.8.1 Blood Tofu
Blood tofu is a traditional dish widely eaten by Chinese people and has a reputation as a scavenger.
Blood tofu production process: blood collection → stirring (adding salt 3%) → loading (blood-water ratio is 1:3) → dicing boiled (water temperature 90 ° C, boil for 25 min) → dicing water immersion → sale
4.8.2 blood sausage
The blood sausage is the traditional food of the residents of northern China. The blood sausage made from sheep blood in Inner Mongolia is a common dish on the table. The blood sausage has the characteristics of simple processing, rich nutrition, and low price.
Blood sausage production process: blood collection → stirring, adding water → adding seasoning → enema → boiled → drying up the pot → selling, eating.
Seasoning formula: pepper 0.1%, MSG 0.1%, green onion 1%, fresh ginger 0.5%, sesame oil 0.5%, refined salt 2%, chopped, mixed Serve.
In the southwestern part of China, glutinous rice is added to the blood of livestock (the glutinous rice is first soaked in hot water for one night), and after mixing evenly, various ingredients are added. After enema, steaming can be sold and eaten. This kind of blood sausage is commonly called "filling", which is very popular among people.
Schedule
Table 1 Composition of dry matter in livestock plasma
Ingredient Content /% Ingredient Content /% Ingredient Content /%
Protein 8.00 sodium 0.35 chlorine 0.38
Glucose 0.06 potassium 0.02 bicarbonate 0.16
Cholesterol 0.12 Calcium 0.015 Sulfate 0.21
Lecithin 0.17 Magnesium 0.003 Phosphate 0.14
Table 2 Chemical composition indicators of blood meal
Project excellence
Soluble protein content /% (not less than) 85 75
Moisture content /% (not greater than) 11 11
Fat content /% (not greater than) 0.4 0.4
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