Study On The Umami Characteristics And Stability Of Sunflower Seed Peptides

Sunflower seed is an important advantageous characteristic oil resource in Inner Mongolia.Sunflower seed meal is the product of sunflower seed oil extraction,and sunflower seed meal is rich in protein.The sunflower seed protein was used as raw material to hydrolyse the sunflower seed protein hydrolysate by using the umami protease.In the early stage,the umami taste value was used as the index.The umami taste sunflower protein hydrolysate was separated and purified by ultrafiltration,gel filtration chromatography and RP-HPLC.The amino acid sequence of sunflower seed peptide was identified by tandem mass spectrometry,but whether it was truly tasty,it still needs to be verified.In this study,sunflower seed peptide with known amino acid sequence was synthesized by solid-phase synthesis method,and its umami characteristics were analyzed.On this basis,the mechanism and stability of its umami were discussed,and its umami enhancing effect with monosodium glutamate(MSG)was also discussed,so as to provide a theoretical basis for the practical application of sunflower seed peptide as food umami base.The main results are as follows:1.Nine sunflower seed peptides SFNVD,EADLYN,ALEPIER,AEDFQV,DFVNPQ,NQLDEYQ,ETPEE,FEGGSIE and GNIFNG were synthesized by solid-phase synthesis.Their purity and molecular weight were analyzed by RP-HPLC and ESI-MS.The results showed that the purity of the synthesized peptides was higher than 95%,and the actual relative molecular weight was consistent with the theoretical relative molecular weight,indicating that the target peptides with high purity were obtained by chemical solid-phase synthesis.2.The TS-5000 Z intelligent taste analysis system was used to determine the umami taste and richness(umami aftertaste)of nine synthetic sunflower seed peptides.It was found that the umami taste values of sunflower seed peptides SFNVD,EADLYN and ALEPIER were 4.51,3.97 and 4.09 respectively,the strongest was SFNVD and the weakest was EADLYN.There was no significant difference in richness values,which were 0.99,1.00 and 1.02 respectively.The umami taste values and richness values of the three sunflower seed peptides were significantly higher than MSG,It shows that sunflower seed peptides SFNVD,EADLYN and ALEPIER have the potential to become new umami agents.3.Molecular docking technology was further used to analyze the mechanism of sunflower seed peptides SFNVD,EADLYN and ALEPIER.Firstly,the umami receptor T1R1 / T1R3 model was constructed by modeller 9.17,the model was evaluated by pull chart,and the molecular docking was carried out by using autodock vine 1.1.2 software.The results showed that the umami receptor T1R1 /T1R3 model constructed by homologous modeling method allowed 99.5% of regional amino acid residues,and the model construction was reasonable;The affinity of sunflower seed peptides SFNVD,EADLYN and ALEPIER with T1R1 /T1R3 was SFNVD > ALEPIER > EADLYN,which were embedded in the flytrap binding domain of T1R1 subunit of umami receptor T1R1 / T1R3,and the main interaction forces with T1R1 / T1R3 were hydrogen bond force and hydrophobic force;Sunflower seed peptides SFNVD,EADLYN and ALEPIER bind to 15 amino acid residues of umami receptor T1R1 / T1R3,among which Asp147,Ser148,Ser276 and Glu301 are the key binding residues;Glutamate,aspartic acid and asparagine residues on sunflower seed peptides are key sites recognized by umami receptors.In conclusion,sunflower seed peptides SFNVD,EADLYN and ALEPIER are embedded in the flytrap binding domain of T1R1 subunit of umami receptor T1R1 / T1R3,which is combined with it through hydrogen bond force and hydrophobic action to make it umami;The intensity of umami is consistent with the affinity of umami receptor T1R1 / T1R3,which is SFNVD>ALEPIER>EADLYN;Sunflower seed peptide has different umami strength,and the amino acid residues and sites bound to the umami receptor are different.4.The effects of processing conditions(pH,temperature)and common food accessories(sodium chloride,sucrose and citric acid)on the umami,richness of sunflower seed peptides SFNVD,EADLYN and ALEPIER were studied.The results showed that when the pH ranged from 4.0 to 8.0,the umami taste value increased with the increase of pH,but the richness value had nothing to do with pH;When heated at room temperature to 121 ℃ for 15 min,30min and 60 min respectively,the umami taste value and richness value do not change with the change of heating temperature and heating time;With the increase of sodium chloride concentration,the umami taste value increased and the richness value remained unchanged;Sucrose had no effect on umami value and rich value;With the increase of citric acid concentration,the umami taste value decreased significantly,but citric acid had no effect on the richness value;Sunflower seed peptides SFNVD,EADLYN and ALEPIER significantly enhance MSG umami.