Study On Separation And Purification Of Protein And Chitin From From Shrimp Shells

In recent years,with the advancement of farming and fishing technology in China,the production of shrimps and crabs has increased year by year,but the problem of scraps generated has to be solved urgently.Shrimp shell contains a variety of nutrients such as fat,mineral calcium,protein and chitin,more and more companies in the industry have extracted chitin from shrimp shells,but with the problems of high cost and pollution.An efficient and environmentally friendly leaching system urgently needs to separate the components of the shrimp shell and make rational use.This paper provides an efficient and environmentally friendly process for separating components from shrimp shells and improving the overall utilization of shrimp shells effectively.The technical conditions for the leaching of fat in the shell of the shrimp by the leaching method were optimized.The ethanol was selected as the best leaching agent and leached for 12 h at 98 °C,and the fat yield was 3.52%,of which the oleic acid content was 30.06%,the content was 8.43% and the DHA content was 9.06%.The methyl esterification conditions of fatty acids were optimized: 80 mg of shrimp oil,dissolved in 4 m L of n-hexane,and 800 ?L of 2 mol/L KOH-CH3 OH solution was added.After shaking for 30 s,it was allowed to stand for 70 min.After adding 1 g of Na HSO4,vibrate vigorously and let stand for 30 min.In six parallel experiments,the average yield of shrimp oil was 3.57%,the relative standard deviation was 5.024%,the EPA content in shrimp oil was stable at 8% to 9%,and the DHA content was stable at 9% to 10%.A new method of mineral leaching and separation of minerals in shrimp shells has been proposed.The optimal decalcification conditions were selected: acid A concentration 2.0 mol/L,temperature 35 oC,ratio of material to liquid 1:10,40 min.The decalcification ability of the acid A was verified.The results showed that the decalcification was complete after once leaching,and the decalcification rate was over 96%.For the decalcification leaching solution,the p H was adjusted and concentrated,and calcium salt was prepared by a natural precipitation method.The new system and characteristics of DESs for separating proteins from shrimp shells were studied.The optimal leaching agent DESs3 and leaching conditions were selected by UV absorption method and Coomassie brilliant blue method: leaching agent concentration 7%,solid-liquid ratio 3:25,temperature 50 oC,reaction time 16 h.The whole process was carried out in six parallel experiments.The average fat yield was 3.63%,the relative standard deviation was 7.52%;the average decalcification rate was 97.68%,and the relative standard deviation was 0.82%;The amount of protein removed was 162.12 mg,and the relative standard deviation was 0.82%.SDS-PAGE gel electrophoresis experiments were carried out on the protein of parallel experiments.It was confirmed that the molecular weight of the protein leached in the shell of shrimp was extensive,and the structure of the shell was studied.The results showed that DESs3 had better preparation effect on chitin.The mechanism of protein leaching was explored by means of UV and FTIR analysis.The results showed that O on DESs3 attacks the N atom in the amide group of the protein,the peptide bond was broken,and a small molecular protein was formed and then dissolved.The C-N bond was broken to form a strong carboxyl group and an amino group.Then,the carboxyl group ionizes to lose hydrogen ions to form COO-,the amino group obtained hydrogen ions to form NH3+,and finally the intramolecular amino acid salt was obtained,and both NH3+ and COO-were present in the same protein molecule.At the same time,the infrared analysis and comparison of decalcified shrimp shells and multiple deproteinized shrimp shells showed that there were characteristic peaks of proteins in the infrared spectrum of the shells after decalcification.The results showed that the infrared peaks of the shellfish and chitin were deproteinized several times.The positions were roughly the same,but the purity was still relatively low,so the separation of proteins needs to be continuously optimized.