Study Of Biosynthesis Rule And Inhibition Of Citrinin In Sufu

Citrinin(CIT)is a secondary metabolite produced by normal metabolism of Monascus species,so did some strains of Aspergillus and Penicillum.Citrinin is mainly distributed in the daily lives of cereals,food,fodder.Sufu is a traditional Chinese beans fermented food,having many kinds of amino acids.However,the citrinin content of red sufu is generally higher than others.In the present,studies are mainly involved in red yeast product about generation rule and control for citrinin,while generation rule and control for citrinin in sufu has not been reported.Therefore,to public health,the content standards of citrinin in sufu should be determined urgently and citrinin should be controlled in sufu processing.This study was carried out in order to determine the content of citrinin in sufu and intestinal products.The survey results showed that the levels of citrinin in sufu ranged between 0.0173 ?g/g and 3.077 ?g/g.Some sufu that not added red yeast rice also detected the presence of citrinin.Due to the different processing,the content of citrinin in north sufu is generally higher than in south sufu.Citrinin can be partly detected in intestinal products added monascorubrin.Among total 23 samples,the incidences of citrinin contamination were 52%,with the mean contamination levels were 0.00862 ?g/g.The Monascus.FM-46 or Monascus.Winter4 solid-state fermentation were tested.The results showed that the content of citrinin in Monascus.Winter4 is reduced to 5 percent of Monascus.FM-46,while pigments are higher than Monascus.FM-46 about 1000 U/g?3000 U/g.Using the traditional method of sufu fermentation,citrinin content changes are monitored during the latter part of fermentation process.Whether it is fermented at 25 ?for one month or at room temperatue for four months,citrinin content have no significant trends of change.Besides,the effect of red yeast rice and fermentation temperature on citrinin content in the latter fermentation period were also studied.Using red yeast rice fermented by Monascus.Winter4 or increasing the latter fermentation temperature can decrease citrinin content.Orthogonal test results showed that 32 ?,35 g rice and 14%inoculation are the optimum conditions.Moreover,the influences of three kinds of addictive(sodium lactate,cyclic adenosine monophosphate,biotin)on biosynthesizing citrinin were investigated.The results indicated that addition of sodium lactate had no inhibitory effect on citrinin biosynthesis.On the contrary,low amount of sodium lactate can improve the biosynthesis of citrinin.The inhibition rates of citrinin could reach 96%and 75%respectively by adding 0.36 g/kg cyclic adenosine monophosphate and 30 ?g/kg biotin.