Study On Oyster Enzymatic Hydrolysate's Taste Characteristics And Heavy Metal Removal Technology

Oyster is a kind of marine bivalve shellfish.It has a wide range of sources,delicious flavor and rich nutrition.It shows important application value in the fields of food,medicine and health care products.In the existing oyster development technology,the enzyme technology has attracted people's attention due to its mild reaction conditions,easy process control and non-toxic and harmless products.Oyster enzymatic hydrolysate is rich in amino acids,small molecular peptides,trace elements and other beneficial ingredients for human body,but it also has the problem of excessive content of harmful heavy metals.In this paper,oyster was used as raw material to prepare oyster hydrolysate by deep enzymatic hydrolysis with complex enzymes,and the flavor characteristics and heavy metal removal process of oyster hydrolysate were discussed.The aim is to provide reference for further processing of oyster.In this paper,the technology of compound enzymatic hydrolysis of oyster was studied with the index of protein hydrolysis degree and protein recovery.The optimum enzymatic hydrolysis process obtained by response surface methodology was as follows: the mass ratio of Flavorzyme500 MG to Pancreatin is 1:3,the time of enzymatic hydrolysis was 7.04 h,the temperature of enzymatic hydrolysis was 50?,and the amount of enzyme added was 0.39%.At this time,the degree of protein hydrolysis and the recovery of protein were 37.82% and 71.87%,respectively.The basic components and flavor characteristics of oyster hydrolysate were studied.After enzymatic hydrolysis,the ash content of oyster enzymatic hydrolysate decreased from 23.01% to 12.75%,and the reducing sugar content increased from 0.71% to 14.04%,indicating that the the ash content of oyster was decreased significantly,and the reducing sugar content of oyster were increased significantly in the enzymatic hydrolysis process.The flavor characteristics and flavor synergism of oyster enzymatic hydrolysate were analyzed.The results showed that oyster enzymatic hydrolysate had strong flavor,full taste,weak acidity and bitterness;it had different enhancement effects on the taste and kokumi of different foods,and the higher the amount of enzymatic hydrolysate added,the more obvious the enhancement effect on food flavor.A total of 31 peptides were identified from oyster hydrolysate by UPLC-MS/MS and De novo sequencing.,and the molecular weights of which were all less than 800 Da.Among them,eight of them might be bitter peptides.Peptides F1-1(AGDDAPR),F1-3(DGAGSSF),F1-6(FGGAGALH)and F2-1(TGSSPAGE)were synthesized by solid-phase synthesis.Among them,the flavor of F1-1 and F1-3 is sour,with a taste threshold of 1000 mg/L;the flavor of F1-6 and F2-1 were sour and delicious,with a taste threshold of 500 mg/L and 2000 mg/L,respectively.The synthetic peptide had obvious flavor enhancement effect in salt solution and the mixed solution of salt and MSG,which indicated that peptides can make the overall taste of food more rich and coordinated.The removal process of harmful heavy metals from oyster hydrolysate was studied.The contents of As and CD in oyster hydrolysate were higher,and the contents of them were 16.5 mg/kg and 7.43 mg/kg,respectively.Which indicated that the removal of As and Cd in enzymatic hydrolysate should be emphasized.Compared with the removal of As and CD in oyster hydrolysate by 0.05% phytic acid and chitosan,the results showed that the adsorption rates of As were 38.14% and 36.02% respectively,and the adsorption rates of Cd were 42.89% and 41.14% respectively.The removal efficiency of harmful heavy metals by phytic acid was better than that by chitosan,but there was little difference between them.Phytic acid and chitosan can both cause loss of beneficial metal elements and peptide segments with molecular weight greater than 1000 Da in the enzymatic hydrolysate.The adsorption rates of phytic acid on Fe,Zn,Cu and Se were 4.97%,19.41%,10.12% and 10.25% higher than those of Chitosan,the loss of peptide fractions with molecular weight greater than 1000 Da is more obvious under the action of phytic acid.Considering the removal efficiency of heavy metals and the loss of nutrients in oyster hydrolysate,chitosan was a better adsorbent for heavy metals.