Ultrasound-assisted Extraction Of Flaxseed Gum And Preparation Of Flaxseed Gum/Soybean Isolate Protein Merad Product

In this study,flaxseed cake meal was used as the raw material to optimize the ultrasound-assisted hot water extraction process of flaxseed gum(FSG)using a singlefactor combined with response surface methodology,and in vitro free radical modeling was applied to analyze the effect of FSG antioxidant activity before and after deproteinization.The preparation conditions were optimized using orthogonal design tests.The physicochemical properties,structural characterization and antioxidant capacity of FSG/SPI were evaluated by in vitro free radical modeling and spectroscopic methods in order to provide a theoretical basis for FSG preparation and its application in the food industry.The main studies and results are as follows:1.In the optimization test of ultrasonic-assisted hot water extraction process,the material-liquid ratio,ultrasonic power,ultrasonic time and p H had significant effects on the extraction rate of FSG.The best extraction process was the material-liquid ratio of 1:50,ultrasonic power of 248.66 W,ultrasonic time of 41.24 min and p H 6.06,and the extraction rate of FSG was 27.12% under these conditions;2.The hydroxyl radical scavenging rate,DPPH radical scavenging rate,ABTS cation radical scavenging rate and total reducing power of FSG(Deproteinized flaxseed gum,DFSG)after deproteinization were 4.04%,11.54%,11.08% and 0.09,respectively,lower than those of FSG before deproteinization;3.In the optimization test of FSG/SPI preparation conditions,p H,reaction temperature and reaction time had significant effects on the preparation of FSG/SPI by hygrothermal method.The optimal preparation conditions were p H 5,reaction temperature 80 °C and reaction time 120 min,and the grafting degree of FSG/SPI was 59.10% under these conditions;4.Compared to FSG and SPI,the structure of FSG/SPI is more dense.The emulsification and emulsion stability of FSG/SPI were better than FSG,and the emulsification and emulsion stability were 3.42 m2/g and 17.67 min higher than FSG,respectively.FSG/SPI had better foaming and foaming stability than FSG,and the foaming and foaming stability were 12.00% and 21.02% higher than FSG,respectively.The results showed that both the foaming and emulsification stability of FSG were improved by the Merad reaction,and also the antioxidant capacity of FSG and SPI were improved respectively.