Studies On GABA Content Changs In Aspergillus Fermented Douchi

The GABA contents in the 39 traditional commercial fermented soybean products from four different types were analyzed by the method of HPLC or Colorimetry.Douchi samples made from two soybean species,Xiaoli 6 and a black soybean species,were prepared by naturally Aspergillus fermentation,and the content changes of GABA were observed in different fermentation stage.The effects of technological treatments,such as budding and adding rice wine before aging,to the content changes of GABA,were also investigated.The results are as follows:(1) The content of GABA in Furu-gravy and the Furu-body were 122.57 mg/100g and 73.52 mg/100g respectively,higher than all the other samples,and in the blue-Furu samples were higher than both the white-Furu and the red-Furu samoles,while in the Furu-gravy samples were higher than in the Furu-body.The contents of GABA in the Soysauce and Douchi were 70.82 mg/100ml and 53.14 mg/100g,and in Soybean paste,only 36.80 mg/100g, the least of all the samples.(2) The crude protein concentration of Xiaoli 6 and balck bean changed during the process of Douchi preparing,decreasing in the former stages,and then increasing in the latter aging stage to 23.3%and 28.7%,a little less than that of materials,which were 38.0 g/100g and 35.9 g/100g respectively.The budding treatment of the two materials was the stage that the concentration of crude protein decreased most,which were 17.7%and 8.8%,while adding rice-wine resulted in the increase the crude protein concentration of 12.11%and 5.68% respectively.(3) The Glu contents in two Douchi samples increased to 14974.9 mg/100g and 14710.4 mg/100g,much higher than that of Xiaoli 6 and the black bean materials.While teated by budding combined with adding rice wine resulted in the Glu content increasement of 50.24%and 66.04%,and the no-budding and adding rice wine treatment,16.33%and 126.28%respectively.(4) The GABA contents in two Douchi samples increased to 923.31 mg/100g and 1012.13 mg/100g,much higher than that of Xiaoli 6 and the black bean materials.The budding treatment of Xiaoli 6 soybean and the black bean resulted in a GABA content increacement of 87.8%and 74.6%,and adding dee wine treatment,31.1%and 28.75%,while treated by budding combined with adding rice wine,the Glu content increased to 1312.35 mg/100g and 1432.61 mg/100g respectively.It was concluded from the results that:(1) The fermented soybean foods contained high relatively high concentration of GABA,indicating that fermented soybean foods can be potential GABA rich food resources.(2) The content changes of Glu and GABA were significantly positive correlative during the process of the XIaoli 6 and the black bean Douchi preparing.The contents of crude protein,Glu,and GABA were all significantly different between the treated samples by budding,adding rice wine,and budding combined with adding rice wine,and the controls, both in the XIaoli 6 and the black bean Douchi preparing.(3) The GABA contnents of Douchi samples increased obviously when treated by budding and adding rice wine both in XIaoli 6 and the black bean samples.