Effect Of Steam Explosion Pretreatment On Structure And Functional Properties Of Sesame Meal Protein

Sesame meal is a by-product of sesame oil extraction.Its protein content can reach 42.5% to 47.9%,and its amino acids meet the human protein standards recommended by FAO/WHO.It is a good source of vegetable protein.Due to the poor physical and chemical properties of sesame meal protein(such as the poor solubility of11 S globulin in sesame protein),its application in food or feed production is affected.Steam explosion(SE)is a green,economical and short-time physical treatment method,which can improve the functional properties of proteins to a certain extent.In this study,SE technology was used to treat sesame meal,combined with alkali extraction and acid precipitation to extract protein,and to explore the changes in its structure and functional properties,aiming to find a new way to improve the functional properties of sesame meal protein,and at the same time for the high value of sesame meal.Development and utilization provide theoretical reference and technical support.The main research contents and results are as follows:1.The sesame meal is pretreated by SE technology,and the protein extraction rate of sesame meal and the changes of crude protein,crude ash,moisture,crude fat and amino acid composition in sesame meal protein samples are studied under different SE conditions.The test results show that the protein extraction rate of sesame meal prepared by steam explosion pretreatment increases with the increase of steam explosion pressure and pressure time,and then remains unchanged,while the protein content in the protein samples gradually decrease,while the change of steam explosion parameters have no significant effect on crude ash,moisture and crude fat in the sesame meal protein samples.The amino acid determination data of sesame meal protein samples under the conditions of no SE,low-intensity SE,and high-intensity SE show that when the SE pressure,dimensional pressure,time increase,the total amount of amino acids in the protein samples show a decreasing trend,the hydrophobicity value of amino acids increase,and the hydrophobicity of sesame meal protein increase.2.The physical and chemical properties of sesame meal protein under different SE pretreatment conditions are studied,including color,surface hydrophobicity,disulfide bond and sulfhydryl content,thermal stability,etc.Mainly for the changes in the secondary and tertiary structure of protein samples,so as to understand the relationship between functionality and structure.The color difference test results show that after SE treatment,the Maillard reaction of sesame meal protein is intensified and the brightness decrease.The stability is enhanced,and the protein molecules become more disordered.The results of flexibility and free sulfhydryl groups and disulfide bonds show that with the increase of SE pressure and pressure maintenance time,the flexibility of sesame meal protein gradually increases,the content of free sulfhydryl groups increases,and the disulfide bond increases.The content of sulfur bonds decrease,and larger aggregates are more converted into smaller aggregates;the surface hydrophobicity and turbidity results show that with the increase of SE pressure and treatment time,the surface hydrophobicity and turbidity of protein samples also gradually increases,the hydrophobicity doesn’t change significantly under higher SE conditions;Fourier transform infrared spectroscopy results show that no new functional groups are generated during the SE process,and the content of β-sheet,β-turn,and random coil increases,and α-The helix is reduced,and the partially ordered secondary structure is transformed into an unfolded or disordered structure;the results of the UV spectrum show that the internal chromophore is exposed after the SE treatment,and the UV absorption intensity is enhanced;the protein glycosylation results show that,the Maillard reaction is enhanced,more fluorescent substances are produced,and the protein fluorescence intensity increases under the low-intensity SE condition of 1.0 MPa for 30 s.With the increase of SE pressure and time,more fluorescent substances are converted to colored substances,and the fluorescence intensity decrease.The result of endogenous fluorescence spectrum test show that the protein fluorescence quenche and the fluorescence intensity decrease after SE pretreatment.3.To study the protein solubility,oil retention,foaming and emulsifying properties of sesame meal extracted under different SE pretreatment conditions,and to analyze the effect of SE pretreatment on the functional properties of protein samples with no SE sesame meal as a control.After SE treatment,the solubility of sesame meal protein increases with the increase of SE pressure and treatment time,but when it reached 2.0 MPa for 120 s and 2.5 MPa for 60 s,the increase isn’t obvious;the oil absorption test results show that the effect of improving the oil absorption of sesame meal protein isn’t significant under the low-intensity SE conditions.When the pressure and time of SE treatment are increased,the oil retention of sesame meal protein is improved.And foaming stability,emulsification and emulsification stability are improved.