Researches On Isolation,Purification,Identification And Properties Of Umami Peptides From Kelp

In this paper,Laminaria japonica was used as raw material to extract umami ingredients by bio-enzymatic method,and the effects of the time of enzymatic hydrolysis,the temperature of enzymatic hydrolysis,the pH value of enzymatic hydrolysis,the solid-liquid ratio and the amount of enzyme addition on the enzymatic hydrolysis of kelp were studied.According to the response surface model building,through the verification test,get best seaweed protein enzymolysis condition was:adding enzyme quantity was 0.3%,pH was 6.38,the material liquid than 1:50?g/mL?,enzyme solution temperature was 52.60?,enzymolysis time was7.64 h,under the condition of the validation test,seaweed protein hydrolysis degree was24.94%.Decolorization and depurination of kelp enzymatic hydrolysate,using active carbon to kelp enzymolysis liquid decolorization processing,through the single factor experiment,orthogonal experiment optimization by active carbon decoloring again the optimal process conditions:activated carbon content of 1.0g/100 mL,temperature of 45?,time of 50 min,the decoloring rate was 56.34%,the polypeptide loss rate was 20.02%.Biological fermentation combined with activated carbon deodorization method was selected to deodorize kelp enzymatic hydrolysates.Single factor experiment was conducted first,and then orthogonal experiment was conducted to optimize the analysis,After that the optimal conditions for yeast deodorization process of kelp enzymatic hydrolysates were obtained:yeast addition amount of 0.4g/100 mL,the temperature of 30?,the processing time of 50 min,the sensory value was 6.75,polypeptide loss rate was 6.17%.Activated carbon was used to deodorize the kelp enzymatic hydrolysate after yeast fermentation.The single factor experiment was carried out first,and the optimal conditions for the second deodorization process of kelp enzymatic hydrolysate after yeast fermentation by activated carbon were obtained through the orthogonal test optimization analysis:Activated carbon dosage was 1.5 g/100 mL,time was 50 min,trends of temperature was45?,after processing the enzymolysis liquid of sensory value of 9.5 points,polypeptide loss rate was 29.38%.After the enzymolysis liquid analyzed by HS-SPME-GC-MS,26,35 and 18 volatile substances were respectively detected before deodorization,after deodorization by yeast fermentation,and after deodorization by yeast-activated carbon combination.After yeast fermentation and deodorization,the total peak area increased by 288.90%,and the peak area of aldehydes,alcohols and ketones all increased.The total peak area was reduced by 74.16%after yeast-activated carbon deodorization.The above main volatile components have been reduced,and the main astringent substance aldehydes are reduced by 78.80%compared with that before deodorization,especially the odorous components such as valeraldehyde,hexanal and heptaldehyde.A series of separation and purification methods including ultrafiltration grading,ge l filtration chromatography and reverse high performance liquid chromatography were used to separate and purify the kelp protease hydrolysate.The umbilical components o f kelp were analyzed and identified by UPLC-MS/MS.Three umami peptides of kelp with molecular weights of 763.38 Da,885.37 Da and 871.83 Da were found,and thei r amino acid sequences were TDIRPY?thr-asp-ile-arg-pro-tyr?,KMGYWDA?lys-met-gly-tyr-trp-asp-ala?and ESGVIPY?glu-ser-gly-val-ile-pro-tyr?.The physicochemical properties and in vitro antioxidant analysis of the isolated and purified lyophilized components showed that the kelp umami components had good solubility,apparent viscosity and autoclaving stability.Through the in vitro antioxidant experiment,the results showed that the kelp umami component showed a certain DPPH free radical scavenging ability,Fe²⁺chelation ability and certain reducing power.Compared with the flavor of yeast extract,it was found that the umami component of kelp was similar to that of yeast extract.The salt reduction effect was outstanding.It was compounded with yeast extract F3803 in a ratio of 2:3,which had the best effect of freshening and reducing salt.