Studies On Detection And Degradation Of Citrinin And Cotrol Technology

Citrinin is the secondary metabolite of fungus and is a mycotoxin of antibacterial activity, nephrotoxicity and teratogenicity. Therefore, limit of detection of citrinin in food has become a hot spot at home and abroad. Recently, there are many methods to detect citrinin such as HPLC, ELISA and TLC. In this thesis, the method of purification of citrinin from food samples, the removal and degradation of citrinin, the ability of mould to produce citrinin and the influence of culture conditions on citrinin production of mould were researched.1、The citrinin in food samples was extracted by60%ethanol, purified by A, and eluted by V(C):V(H2O)=80:20(pH2.1). Then the eluate was detected by HPLC-FLD. The column was Shimadzu Hypersil ODS2,(5μm,250x4.6mm). The mobile phase composition was V(acetomtrile):V(H2O)=30:70(pH2.5), fluorescence detector:λex=331nm, λem=500nm. There was good linear relationship between the fluorescence detection values and citrinin concentration in the range of100μg/mL-0.01μg/mL (R2=1.0000), and the RSD was0.074%.The detection limit of citrinin purified from food was lower, and the citrinin in food can be well separated from other impurities. Meanwhile, the recovery of citrinin purified from food was about80%. Among the30kinds of food that be detected, vinegar, millet wine, cereals, rice wine and fruit juice were safer. And the contents of citrinin in soy sauce and fermented bean curd were higher than others with3.2513μg/mL and6.0301μg/g.2、The contents of citrinin reduced in red kojic rice were proportional to high temperature degree, high moisture content. The citrinin could be eliminated by high or low pH. Only a little of citrinin were degraded when added salinity was less than12%. However,50%of citrinin were degraded when added salinity were14%or16%. Citrinin extracted from the red kojic rice treated with120℃or160℃did not show bactericidal inhibition zone, while it treated with140℃had inhibition zone. Citrinin thermal degradation products treated with140℃was identified as Citrinin H2, and the citrinin degradation products in ambient temperrature was identified as Citrinal A.3、Two fungi produce citrinin were isolated from purchased Monascus powder and orange peel, and they were identified as Monascus anka Nakazawa et Sato and Penieillium citrinum Thom. The citrinin production ability of Penicillium citrinum Thom was stronger than Monascus anka Nakazawa, Aspergillus oryzae and Aspergillus niger with64.21μg/mL in MSG. The citrinin content in culture medium increased gradually with fermentation time, then decreased after the peak. Moreover, different strain has its optimum temperature to produce citrinin. The citrinin content in culture medium was found to be higher in higher pH. And at pH7.7, the citrinin content of Aspergillus oiyzae has reached the highest point. However, the ability to produce citrinin of this four fungi can be lowered, when there were ammonium salts and EDTA in the culture medium. And ammonium sulfate and ammonium nitrate played the biggest role in it.