Study On Enzymatic Extraction And Refining Of Acaudinaleucourocta Protein Peptide

Acaudina leucoprocta has been proved a high-quality protein resource as same as stichopus japonicas. The protein and amino acids content of it were very high, while the fat was relatively low. However, the dense and hard surface dirt layer contains very high level of heavy metals such as lead, arsenic and so on. Moreover, the fishy smell of stichopus japonicas is heavy and not easy to remove. In a word, these disadvantages hindered the further development of Acaudina leucoprocta. Being aimed at solving these problems, study of deodorization by surface microorganism fermentation of the overall Acaudina leucoprocta that have been treated in advance with exogenous enzymes and organic acid to remove the heavy metals has been carried out, and high yield of Acaudina leucoprocta peptide was obtained by autolysis and subsequent exogenous enzymatic hydrolysis.And furthermore, the refinement reararch of Acaudina leucoprocta peptide was also done.The result of the deodorization by surface microorganism fermentation of the overall Acaudina leucoprocta showed that the content of fishy smell in Acaudina leucoprocta has decreased after24h fermentation with different concentrations of saccharomyces cerevisiae and Anqi bread yeast. Unsaturated aldehydes which contributed largely to fishy smell have reduced by more than50%. The nonyl aldehyde and heptyl aldehyde in Acaudina leucoprocta with107saccharomyces cerevisiae were not detected. It has been proved a suitable method for deodorization.The optimal enzymatic hydrolysis conditions were determined by orthogonal test The results showed as follows:pH10,50℃,time3h for autolyzing and enzyme dosage0.4%,60℃, substrate concentration6%, time90mins for protamex hydrolysis. On these conditions, peptide yield reached52.63%, the molecular weight of the obtained Acaudina leucoprocta peptide distributed mostly within200-1000Da. That belongs to small molecule peptide and owned the good absorbency. Accoding to our analysis, the peptide product contains2.87%of polysaccharide and0.026%of saponin as well. The IC50(half maximal clearance rate or half maximal inhibitory concentration) of hydroxyl free radical clearance rate, superoxide free radical clearance rate, ACE inhibitory activity was10.994mg/mL,23.085mg/mL and0.423mg/mL respectively. It demonstrated best solubility when pH was7. And boiling water bath for30minutes has little influence on its solubilityThe optimal refining conditions for the Acaudina leucoprocta peptide were determined by orthogonal test. The results showed as follows:cation exchange resin(D113) dosage6%, pH7,35℃, time1.5h. On these conditions, the content of nonyl aldehyde, hexanal and heptyl aldehyde in hydrolysate reduced from1.18%to0.62%,10.5%to5.12%and0.79%to0.47%. On the basis of the optimal process, desalting rate reached93%with anion exchange resin(717)at dosage9%, pH7,35℃for1h.This study laid a solid foundation on the further development for Acaudina leucoprocta.