| The crab shell is the main components of portunid wastes which produced during the processing of the portunid, includes the rich resource of chitin and calcium,has the high use value. The comprehensive utilization of these waste can not only save resources and protect the enviroment,but also to create a good economic value an social value.This paper studied one way and the related content of comprehensive utilization of the portunid carapace. Concrete as follows: Studied the extraction technology of crab chitin from the portunid carapace by acid alkali method. Studied the preparation technology of crab chitosan from crab chitin by alkali method. Studied the application of crab chitosan in clarifying sugarcane juice. Recying calcium from calcareous solution which was produced during the extracted crab chitin, further, studied the prepartion technology of calcium citrate malate from recying calcium carbonate. Examination quality of crab chitin and chitosan and calcium citrate malate of reelated products from comprehensive utilization of the crab shell.The optimum elimination calcium conditions for extracting crab chitin were studied by single factor analysis test as follows: chlorhydric acid concentration 6%, acid treatment time 4h, treatment temperature 25℃; The optimum elimination albumen conditions as follows: sodium hydroxide concentration 6%, alkali treatment time 2h, alkali treatment temperature 90℃. Base on this experiment,the productivity of crab chitin is 15.57%. Its qualities indexes are reach to standard of edible chitin.The optimum preparation crab chitosan conditions were studied by single factor analysis and orthogonal test as follows:particle sizes80, sodium hydroxide concentration 50%, temperature 100℃, ratio of liquid to material 15:1, time 10 h . Base on this experiment,the yield of crab chitosan is 75.62%. Its qualities indexes are reach to standard of edible chitosan.The optimum application conditions of crab chitosan in sugar cane juice were studied by single factor analysis and orthogonal test as follows: degree of deacetylation,dosage 0.45g/L, temperature 50℃,pH 4, time 45 min. Base on this experiment, The sugar cane juice transmittance enhances from 46.41% to 93.54%. Its nutritional value was maintained basically while clarified by crab chitosan, it indicated that the crab shell chitosan is one kind of effective clarifying agent.The recying calcium preparation conditions from calcareous solution through the experiment were studied as follow: volume ratio of calcareous solution to 30% sodium carbonate solution 100:9. The optimum preparation calcium citrate malate were studied by single factor analysis and orthogonal test as follows: molar ratio of material(calcium carbonate, citric aid, malice acid)10:3:7, temperature 50℃,time 2.5h, ratio of liquid to material 3:1.Base on this experiment, solubility of calcium citrate malate is 963.5mg/100ml water. It is a good calcium nutrient additive which its calcareous quantity is moderate and has good solubleness and a wide range applicability of temperature and pH.
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