Study On Ultrasonic Modification Of Oat Globulin

Oat protein is a source of superior plant protein,which has high content and many kinds of amino acids.With sufficient production and abundant nutrition value,oat protein had increasingly attracted people's interest and attention.In this paper,oat globulin was isolated by adjusting the oat globulin salt solution pH,and ultrasound was used to change the physicochemical properties and structure of oat protein.The main research contents are as follows:1.Oat globulin salt solution was fractionated by Osborne fractions and oat globulin was isolated by adjusting pH.The results of single-factor experiments showed that the purity of the globulin was 88.6%,obtain by following ways:at first adjusting oat globulin salt solution pH to 4,then watering precipitation twice and adjusting oat globulin water solution pH to 6 in the first washing.It was also found that the solubility of the acid-precipitation globulin was better than that of the dialysis globulin.2.Ultrasonic treatment can improve the solubility of oat globulin.With the increase of ultrasonic power and time,oat globulin solubility gradually increased.Compared with untreated sample,the emulsification and foaming ability of ultrasonic treated oat globulin were improved.With the increase of ultrasonic power and time,the emulsification and foaming ability of ultrasonic treated oat globulin increased at first then decreased.3.Particle size determination,surface hydrophobicity,UV absorption spectra,fluorescence spectrophotometry,CD spectra and SDS-PAGE were performed to analyze the effects of ultrasonic treatments on protein structure of oat globulin.The results showed that ultrasonic treatments included association/dissociation of the oligomer,formation of soluble aggregates.With the increase of ultrasonic power and time,the molecular structure of protein was expanded and the hydrophobic amino acid residue was exposed,resulting in an increase in the UV absorption intensity and surface hydrophobicity of the globulin and a decrease in the fluorescence intensity.The a-helix and ?-structure content of globulin decreased significantly while the random curl content of globulin increased with ultrasound treatment.However,ultrasound treatment had no significant effect on the primary structure of globulin.4.Ultrasound treatment could enhance the oat globulin heat-induced gel property and viscoelasticity.The results of scanning electron microscopy showed oat globulin heat-induced gel network structure had denser and more uniform with ultrasound treatment than no ultrasound treatment globulin gel.LF-NMR results showed ultrasound treatment had no significant effect on the water activity of globulin heat-induced gel,but ultrasound treatment could increase the UV intensity and decrease in the fluorescence intensity of globulin alkaline solution.Moreover,the soluble aggregation increased significantly,which was beneficial to the formation globulin gel with ultrasound treatment.5.Single factor experiment results showed glucono-deta-lactone(GDL)gel optimum preparation conditions were as follows:heating temperature 90 0C,concentration of NaCl 1 mol/L,GDL 3 g/100 mL.The effects of ultrasonic pretreatment on oat globulin GDL gel were studied.With the increase of ultrasonic power and time,the gel property and water holding capacity of GDL gel was enhanced.LF-NMR results showed the ultrasound pretreatment GDL gel has a lower water activity than no ultrasound pretreatment GDL gel.Ultrasound pretreatment could enhance GDL gel's viscoelasticity and with the increase of ultrasonic power and time,the GDL gel of storage modulus and loss modulus were gradually increased.The results of scanning electron microscopy showed that the ultrasound treatment GDL gel structure was denser and more uniform.