Study On The Biogenic Amines And Decarboxylase Activity In Bacteria Fermented Douchi

Douchi is a kind of condiment. It's a favorite flavor becase of the increase of value on food safety,the unique of flavour and its has certain pharmacological effects. biogenic amine contents is too high will cause certain toxic effects on human health, at the bacteria-fermented Douchi in the fermentation process,so it is a necessity for determination of the content of biogenic amines.The study dynamically determinate the content of biogenic amies and tyrosine decarboxylase activities on bacteriafermented Douchi samples of different stages.(1)In this work, the content of biogenic amine in bacteria-fermented Douchi was detected dynamically by HPLC. The results showed that the dansyl chloride as a derivative reagent were precolumn derivatization, Agilent XDB-C 18(150 mm × 4.6 mm, 5 ?m) for column chromatography, 8 biogenic amines(tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine) were separated effectively within 20 min. Inoculated with Bacillus subtilis(B.subtilis BJ3-2) to strengthen the pure fermentation conditions of dynamic detection of biogenic amine content, the content of tyramine, at 60 h reached to 154.59 mg/kg; the total biogenic amines are firstly increased and then decreased in the pre-fermentation and post-fermentation, the range was 58.08~227.14 mg/kg and 71.18~131.8 mg/kg. During natural fermentation stage, the spermidine content was the highest at 42 h up to 35.8 mg/kg. The biogenic amines content in total is increased, the range was 56.59 ~98.56 mg/kg and 30.26~63.48 mg/kg in pre-fermentation and post-fermentation stages. Pure fermentation and natural fermentation conditions, Tyrosamine and phenethylamine content great change, maybe due to the fermentation chamber was polluted in factory.(2) Single factors effect on tyrosine decarboxylase(TDC) pure enzyme was studied.Using L-tyrosine as substrate, PLP as a cofactor, to determine the optimal conditions for the TDC produced in the reaction of tyramine. Taking into account the TDC of stability, in temperature is 40?, pH = 7, add coenzyme(PLP) to 0.2 mmol /L, add L-tyrosine as 0.5 mmol/L conditions is tyrosine decarboxylase(TDC) activity is the best.(3)The activity of TDC enzyme can influence tyramine formation in bacterialfermented Douchi. Under the pure fermentation conditions, TDC activity is the highest at the pre-fermentation 36 h and at the post-fermentation stage 3 d, were 9.26 U/g and 4.45 U/g, respectively. And the natural fermentation conditions,it were 72 h pre-fermentation and 3 d at the post-fermentation stages,4.32 U/g and 2.04 U/g, respectively.In summary, we can draw a conclusion that the content of biogenic amines can be decreased by controlling the parameters of fermentation process in theory. The temperature control in 35?~40?, salt concentration by adding 6%, monosodium glutamate adding amount was about 10%, add a lower concentration of tea-water, add the soy sauce 2%, reduce the ginger and pepper add amount etc. This way can decline the tyrosine decarboxylase(TDC) activity, thereby reducing accumulation of the tyramine.