Studies On The Determination Methods Of Aflatoxins And Ochratoxin A In Ginger And Related Products

Objective:Develop methods for simultaneous determination of aflatoxins G2, G1, B2,B1and ochratoxin A in ginger, for providing the basis for the establishment of analytical method for multi-mycotoxins in other traditional Chinese medicines. Study the growth and toxin-producing conditions of Aspergillus flavus and Aspergillus carbonarius on ginger, for providing the basis for the safe use of ginger.Methods:①Three methods including UFLC-MS/MS, HPLC-PCD-FLD, UHPLC-FLR have been developed for the simultaneous determination of aflatoxins G2, G1, B2, B1and ochratoxin A in ginger.②Aspergillus flavus and Aspergillus carbonarius were inoculated on ginger, respectively, then the mycotoxin contents were detected by after a few days’cultivating, to study on the growth and toxin-producing conditions of Aspergillus flavus and Aspergillus carbonarius on ginger.Results:①Results of UFLC-MS/MS:The LODs and LOQs of five mycotoxins were0.04-0.3and0.125-1μg/kg, respectively. The recoveries were82.0%-100.2%. Among10batches of ginger,1batch was contaminated by aflatoxin B1with level of1.02μg/kg and1batch was contaminated by ochratoxin A with level of0.53μg/kg. All the contamination levels were below the legally allowable limits.②Results of HPLC-PCD-FLD:The LODs and LOQs for the five mycotoxins were0.03-0.3and0.1-0.9μg/kg, respectively. The recoveries were81.3%-100.8%. Among25batches of samples, moldy gingers were contaminated seriously, while none of the five mycotoxins were found in normal gingers. Ginger powder samples were contaminated slightly. Ginger tea bags were mainly contaminated by ochratoxin A at1.05-1.19μg/kg and ginger black tea bags were mainly contaminated by aflatoxins at3.37-5.76μg/kg. All the contamination levels were below the legally allowable limits.③Results of UHPLC-FLR:The LODs and LOQs for the five mycotoxins were0.005-0.2and0.0125-0.5μg/kg, respectively. The recoveries were84.2%-97.4%. Among30batches of samples,5batches were contaminated with aflatoxin B1at0.13-1.38μg/kg, while5batches were contaminated with ochratoxin A at0.31-5.17 μg/kg. All the contamination levels were below the legally allowable limits.④Results of contamination:As for ginger with Aspergillus flavus inoculated on the surface, the content of aflatoxin B1increase progressively from outside to inside. Aflatoxin B2was only found in the innermost layer with a small amount. As for ginger with Aspergillus flavus inoculated on the transection, the content of aflatoxin B1tended to decrease with the increase of distance and aflatoxin B2was only found in the part of0-0.5cm with a small amount. As for ginger with Aspergillus carbonarius inoculated, ochratoxin A was only found in the inoculated part.Conclusions:Three methods for simultaneous determination of aflatoxins G2, G1, B2, B1and ochratoxin A in ginger developed in the study were simple, rapid, sensitive and repeatable, and each method has its own merits, so researchers should choose the appropriate test method according laboratory conditions and experiment funds. Aspergillus flavus can grow in the inner part of ginger and produce lots of aflatoxins, therefore, ginger which get moldy was inedible any more.