Ultrasound Promoted Ferulic Acid Release From Bran By Fermentation Of Neurospors Sitophila

In this thesis,the ultrasonic-assisted fermentation technology was used to improve the production of ferulic acid by the fermentation of Neurospors sitophila.The effects of ultrasonic pretreatment on the production of ferulic acid from bran fermentation by Neurospors sitophila were investigated by applying different ultrasonic treatment in the three stages of fermentation.The effect of ultrasonic treatment on ferulic acid production in different fermentation stages was studied,and the effect of ultrasonic-assisted extraction after fermentation on the release of ferulic acid was discussed.Firstly,ultrasonic pretreatment of bran was carried out to investigate the effects of ultrasonic temperatures,ultrasonic power and ultrasonic time on ferulic acid production by the fermentation of Neurospors sitophila.Taking the total ferulic acid as the index,the optimal ultrasonic pretreatment conditions were determined.The results showed that when the ultrasonic temperature was 50?,the ultrasonic power was 324 W,and the ultrasonic treatment was 20 min,the extraction amount of total ferulic acid reached the maximum at 72 h,which was 0.35 mg/mL,1.35 times that of the control group.Ultrasound treatment changed the dense network structure of bran cell wall,increased the dissolution of hemicellulose,xylan and other macromolecules,which was beneficial to the fermentation of Neurospors sitophila and the release of ferulic acid.Secondly,by applying ultrasonic treatment at different time in the fermentation process of Neurospors sitophila and stimulating Neurospors sitophila with different ultrasonic time and interval,the change of the extraction amount of total ferulic acid in the fermentation process was studied.And the correlation between ferulic acid extraction amount and ferulic esterase,xylanase and cellulase activities was investigated after different ultrasonic treatment in the fermentation process.The final results showed that the maximum extraction amount of ferulic acid was 0.43 mg/mL,which was 1.31 times that of the control group.When the fermentation broth was treated by ultrasonic treatment at 48 h,the ultrasonic time was 5 min and the ultrasonic interval was 30 s every 30 s.The highest activity of ferulic esterase,xylanase and xylanase in the fermentation process was 8.55 U/mL,4.48 U/mL and 3.21 U/mL,which were 1.51,1.48 and 1.14 times as much as of that in the control group,respectively.Appropriate ultrasonic stimulation in the fermentation process can change the permeability of cell membrane,promote the release of enzymes,and then accelerate the release of ferulic acid.Through Box-Behnken response surface experiment,the optimal experimental conditions were as follows:the initial time of ultrasound was 53 h,the ultrasonic time was 5 min each time,and the ultrasonic interval was 32 s every 30 s.Under these conditions,the total ferulic acid extraction amount was 0.43 mg/mL.Finally,after the fermentation of Neurospors sitophila,different ultrasonic temperature,different ultrasonic power and different ultrasonic time were applied to assist the extraction of ferulic acid to study the change of the total ferulic acid extraction amount.The optimal ultrasonic extraction conditions were investigated with the extraction amount of ferulic acid as the index.The results showed that after fermentation,when the ultrasonic time was 25 min,the ultrasonic temperature was 40?,and the ultrasonic power was 324 W,the maximum extraction amount of total ferulic acid was 0.46 mg/mL,which was 1.07 times that of the control group,and about 92%ferulic acid in bran can be released under these optimal conditions.Therefore,the use of ultrasonic-assisted and microbial fermentation to prepare ferulic acid can significantly increase the amount of ferulic acid extraction,which provides a cheap and simple method for the efficient production of ferulic acid,and has a good development prospect.