Characteristic Flavor Components Of Lysine Short-chain Peptides In Fragrant Sunflower Oi

At present,fragrant sunflower seed oil sold in the market has good color,but its aroma is not intense,and the substrates and mechanisms of characteristic aroma are not clear,which restricts the quality improvement of fragrant sunflower seed oil.Therefore,it is a key problem to explore the characteristic aroma components of fragrant sunflower seed oil from the perspective of substrates in the production process of fragrant sunflower seed oil.From the point of view of Maillard reaction precursor,the Maillard reaction model of peptides close to fragrant sunflower seed oil system is established to analyze the generation of pyrazines,which is expected to provide reference for the control of aroma of sunflower seed oil and the establishment of aroma standard.First of all,the effect of free amino acids and peptides on the generation of volatile compounds after the hydrolysis of sunflower seed protein was analyzed.The main volatile substances generated by Maillard reaction of sunflower seed protein were analyzed,and the influence of hydrolyzed peptides and free amino acids on the generation of main volatile substances was analyzed.By optimizing the heating temperature and time in the Maillard reaction,the optimum reaction condition of the peptide model was selected.Secondly,the changes of amino acids during sunflower seed baking were analyzed and the main amino acids in sunflower seed baking were selected.Based on the analysis of the effect of hydrolyzed peptides and free amino acids on the characteristic volatile substances of sunflower seed oil(pyrazine compounds)in the first part,the Maillard reaction models of lysine-containing short chain dipeptide and tripeptide were established in the experiment,and the pyrazines generated by each model were analyzed.The conclusions were drawn from the above research:(1)Pyrazines were the most volatile compounds in the free amino acid model system and hydrolyzed peptide model system.Moreover,different models have significant effects on the formation of pyrazines.The hydrolyzed peptide model produced the most types of pyrazines and the highest peak area.It is suggested that short chain peptides can promote the formation of pyrazines in Maillard reaction.(2)Heating temperature and time have important effects on the formation of volatile compounds in Maillard reaction.High temperature is beneficial to the formation of pyrazines,but too long heating time has a negative effect on the formation of pyrazines.When the heating temperature is 140? and the heating time is 90 min,the pyrazines generated by the system have the highest types and peak area.Therefore,the heating temperature of 140? and the heating time of 90 min are considered to be the optimal reaction conditions for the three models.(3)The main amino acids in sunflower seed baking were lysine,histidine and arginine,thus,the Maillard reaction model of dipeptides and tripeptides composed of these three amino acids was established.(4)The content of pyrazines in lysine dipeptide model was higher than that in lysine tripeptide model and free amino acid model.The C-terminal or N-terminal amino acids of lysine dipeptides have important effects on the formation of pyrazines.In the C-terminal lysine dipeptide model,the order of total pyrazine content model was Arg-Lys>His-Lys,while in the N-terminal lysine dipeptide model,the order of total pyrazine content was Lys-His>Lys-Arg.In addition,2,5(6)-dimethylpyrazines and 2,3,5-trimethylpyrazines are the main pyrazines in the lysine dipeptide model.In addition,for the lysine tripeptide model with different amino acid sequences,the N-terminal lysine or arginine tripeptide model detected more contents and types of pyrazines than the N-terminal histidine tripeptide model.The total content and percentage of pyrazine were similar in the N-terminal amino acid tripeptide model.It is concluded that the N-terminal amino acids in the tripeptide model have an important effect on the formation of pyrazines.In conclusion,lysine-containing short chain peptides have significant positive effects on the formation of pyrazines,and the effect of peptides with different structures is different.Thus,the studies are expected to provide reference for the control of characteristic aroma of sunflower oil and the establishment of aroma standard of sunflower oil from the perspective of peptide precursors.