The Analysis Of Citrinin In Monascus Products And Study On Fermentaton Control

In this paper,we analyzed the pollution condition of citrinin in Monascus products which are sold in Tianjin,The effects of fermentation conditions on the production of pigments and citrinin by Monascus were also studied.A total of 74 samples which were added red yeast rice or Monascus pigments,purchased from Tianjin market were analyzed.None of sausages,meat products and biscuit samples were found to contain citrinin by HPLC in Out of total 13 fermented bean curd samples analysed,citrinin was detected in 12 samples ranging from 0.56 to 3.43 mg/kg,all of them add red yeast rice.Out of total 4 Red yeast rice and Monascus pigments sold in market 3 samples were polluted by citrinin.Monascus strains were separated from red yeast rice and the results of identified show it were Monascus purpureus.The fermentation condition of the Monascus purpureus was investigated.The fermentation products have only 19.7%the citrinin content of raw red yeast rice.The results show that the cultivate conditions have great influence on citrinin production.In order to understand the difference raw materials fermented by Monascus on the effect of pigment and citrinin,we utilize 8 cereals,4 tuber crops,and argo-industrial residues fermentated Monascus.Fermentation results show that millet flour,naked oats flour,sorghum flour as materials can reduce the yield of citrinin,the yield was only 0.05 mg/L,0.08 mg/L and 0.25 mg/L,respectively.The ordyceps sinensis residues was unfavorable for production of citrinin that was only 0.15 mg/L and at the same time higher pigments were achieved.When tuber crops as substrates,cassava was suitable for Monascus fermentation.Monascus fermented cassava raw material for a more in-depth research.The results show that pH has a significant effect on the production of citrinin.Further experiments showed that nitrogen source was directly related to the pH.Comprehensive results show that fewer citrinin was produced at low pH and no citrinin biosynthesis at pH 2.0.When the pH value was high,there was more red pigment synthesise,and when the pH value was low,there was more orange pigment synthesise.The experiments of adjusting the pH of Monascus culture medium by phosphoric acid or adding phosphates to culture medium can observably increase the yield of pigments anddecrease the yield of citrinin.Diammonium phosphate concentrations of 0.5 g/L was found to be the most suitable for liquid Monascus culture,there was almost no citrinin in broth.