Chitin
Operation points: 1 Immerse 50 kg of crab shell in 75 kg of 5% dilute hydrochloric acid solution, stir well, cover the wood and stone blocks, so that the shell is completely immersed in hydrochloric acid. After 24 to 28 hours, the crab shell is softened. All the calcium contained in the solution can be removed and packaged in a dilute fish. Rinse with clean water repeatedly to remove fleshy matter and other impurities from the shell and wash until neutral. Two 40-kilogram solutions with a concentration of 8% - 10% caustic soda Put it in a pot and boil, put the shell into the pot and boil it for about 1.5 hours until the protein and fat are completely dissolved. Rinse the shell into the stupid water and rinse it with water until it is neutral, then press it dry. 3 Take 78 grams of potassium permanganate, 40 liters of water into the sand tank and mix well. Put the shell into the jar. At this time, the solution in the sand tank becomes brown due to oxidation. After 1 hour, the shell is collected into the pan. , Repeatedly rinse with water. 4 Take 453 g of sodium sulfite, 50 liters of water and pour the shell into another sand jar and mix well. The shell material is gradually bleached. Add 25 liters of water and dip for 15 minutes. Add 5% dilute hydrochloric acid 2.5 kg and stir. 5 minutes, when the shell is pure white, it can be picked up and washed in water. Then it is squeezed to remove the water and dried on the flat bamboo. It is insoluble chitin. 5 will be 40% caustic soda. 37.5 kilograms are distributed in 4 Amoy jars. Each jar is immersed with about 10.6 kilograms of insoluble chitin. Stir uniformly and move into the drying room. Drying room temperature is gradually increased from 40°C to 60°C and maintained at 60°C. After 24 hours, stir 1 time every other hour, and gradually extend to 5 hours to stir 1 time. 6 Take a small amount of sample and wash it. Place it in 1% acetic acid to test. If it can dissolve completely, it means it is good, otherwise it will be prolonged. Incubation time, until soluble, with a wooden scoop into the oyster sauce, rinse with cold water until neutral, and then squeezed to moisture, spread on a flat bamboo basket to dry, that is, soluble chitin.
Comprehensive utilization of shrimp
Shrimp production
Operation points: 1 Thaw the shrimp head, and use a mincer to twist the shrimp head into a pellet of about 5 mm. 2 Place the shrimp head into a sandwich pot, add equal volume of water and 25% vegetable oil, and boil for 15 minutes. Set for 3-5 hours. 3 Centrifuge the supernatant in an oil-water centrifuge at 5000 rpm for 5 minutes to obtain a dark red transparent crude product. 4 Remove traces of water by heating to obtain refined products of shrimp brain oil. .
Chitin and chitosan production
Operation points: 1 Add 6% - 8% hydrochloric acid solution into the shrimp shell and mix well and soak for 24 hours. The calcium carbonate in the shell will produce calcium chloride and dissolve out. Remove the soft shell and rinse thoroughly with water until it is neutral. .2 In a soft shell, add 8% - 10% sodium hydroxide solution to boil, so that the protein and fat are completely decomposed, remove and rinse with water until there is no alkaline reaction. 3 Use 0.5% - 1% permanganate Potassium solution impregnated soft shell, oxidative removal of pigment impurities.4 Rinse the soft shell with dilute acid, and then dilute alkali for the second alkali boiled, can also play a role in bleaching. 5 The chitin is impregnated with 40% sodium hydroxide solution , Insulation 50--60 °C, 24 hours after the pressure of the impregnating solution, washed in warm water at 30 °C 1 times, and then washed to avoid alkaline, dried to obtain chitosan.
The edible parts of the crabs account for about 1/3 of the whole body, and most of them are crab shells. The crab shells are subjected to chemical treatments such as decalcification, fat removal, bleaching and deacetoxylation to make soluble chitin, insoluble in water and alkalinity. The solution can be dissolved in 0.5% - 2% dilute acetic acid to form a white and transparent colloidal solution with high viscosity. It can be diluted with water at any proportion without sedimentation. It is textile, printing and dyeing, man-made fiber, paper making, wood processing, plastics As well as a raw material for medicine and other aspects, synthetic fiber made of chitin is soft and shiny, and comparable to wool. Extraction of chitosan from chitin into surgical sutures does not cause wound infection because Can be absorbed by the body without stitches. Because half of the crab shell is chitin polysaccharide material, with caustic soda solution can be obtained keto acid, which can do coagulant.