Produce of γ-Aminobutyric Acid by Extruded Rice Bran Fermented
|School||Tianjin University of Science and Technology|
|Course||Of Food Science|
|Keywords||extrusion rice bran γ-aminobutyric acid fermentation Aspergillus oryzae|
China is rich in rice bran resources, but its deeply exploitation and utilization were still in low level. In this article, twin-screw extrusion which is the most common technology in food processing was used to process the rice bran, without affecting the activity of various biological components. The extruded rice bran was as raw materials to product the y-aminoburyric acid by liquid and solid state fermentation using Aspergillus Oryzae.In this way,the γ-aminoburyric acid content could be greatly improved, reached the purpose of enrichment of γ-aminoburyric acid.The effect of the extrusion processing of rice bran on γ-aminoburyric acid yield by extruded rice bran fermentation was studied. The γ-aminoburyric acid content of the fermentation product was also different due to the extrusion processing. The optimal extrusion conditions for rice bran were water content of20%, screw speed of200r/min and extrusion temperature150℃, the γ-aminoburyric acid contents of fermentation product were118.6mg/100g and121.1mg/100g by liquid and solid state fermentation. Conditions for liquid state fermentation method was at28℃,130r/min,2days of cultivation,7.5%of inoculation quantity, and the conditions for solid state fermentation was at32癈.3days of cultivation,7.5%of inoculation quantity and90%of relativehumidity.The analysis of the cellulose, hemicellulose, soluble dietary fiber content in the extrusion condition showed that the content of soluble dietary fiber increased slightly and the amount is almost equal to the loss of himicellulose and cellulose. In addition. the residual vitality of peroxidase in extruded rice bran was less than4%, it showed peroxidase and lipase activity were greatly passivated by extrusion, so the free fatty acids would increase slowly during storage period. The experimentations were carried out about the effect of the fermentation products on the a-amylase activity, glucoamylase activity and the ability to remove DPPH·. Liquid fermentation product could reduce the α-amylase activity, but solid fermentation product increased the a-amylase activity. Both liquid fermentation product and solid fermentation product can restrain glucoamylase activity. And through the experiment of research the ability to remove DPPH·, the bacterial fermentation products have certain antioxidative ability.