Occurrence of Aflatoxins and Ochratoxin A and Contamination levels in Cocoa beans from Uganda

Cocoa is a major commodity of great economic importance globally. In Uganda the production and export of cocoa beans is an essential component of the country’s agricultural sector and social economic transformation however during stages of primary processing cocoa becomes susceptible to attack by various mycotoxigenic fungal species which produce mycotoxins. The mycotoxins of great agroeconomic and public health concern in the cocoa industry globally are ochratoxins and aflatoxins (Afs). This study investigated occurrence and concentration levels of aflatoxins and ochratoxin A (OTA) in cocoa beans from three cocoa growing agroecological zones of Uganda. The occurrence of aflatoxins and ochratoxin A was evaluated in 270 fermented and dried cocoa beans randomly collected from farmers from three cocoa growing agroecological zones of Uganda. The occurrence and concentration of these mycotoxins was determined using Liquid chromatography-tandem mass spectrometry (LC-MS/MS) after immunoaffinity column clean up. The occurrence and concentration level of aflatoxins and ochratoxin A varied across the three agroecological zones of Uganda. The study revealed that 77.04% (208/270) of the samples were contaminated with one or more aflatoxin types. The mean aflatoxin concentration was 4.50 ± 0.62µg/kg and ranging from 0.02µg/kg to 50.98µg/kg. Ochratoxin A was detected in 53.33% (144/270) of the analyzed samples. Twenty-three samples (8.5%) exceeded the maximum limit of 10µg/kg for aflatoxin set by the Brazilian legislation. The mean concentration of OTA was 1.97 ± 0.21 µg/kg and ranging from 0.02 µg/kg to 7.61µg/kg. None of the cocoa samples was above the maximum limit of 10µg/kg for OTA in cocoa beans established by the Brazilian legislation. Only 17.41% of the analyzed samples exceeded the threshold of 3µg/kg for OTA in cocoa powder established by the European Commission (EC). The highest level of aflatoxin contamination was observed in Lake Albert crescent agroecological zone with mean concentration of 8.83 ± 1.37µg/kg while the lowest aflatoxin concentration was observed in western range lands agroecological zone with mean aflatoxin contamination level of 0.08 ± 0.01µg/kg. The mean concentration of aflatoxin in Lake Victoria crescent agroecological zone was 2.48 ± 0.29µg/kg. The most prevalent aflatoxin type in aflatoxin contaminated cocoa bean samples were aflatoxin G2 (77.04%), aflatoxin B1 (43.33%), aflatoxin G1 (32.22%) and aflatoxin B2 (17.78%). The mean concentration of AFB1 was 2.45µg/kg with an interval of 0.02µg/kg to 21.14µg/kg. Lake Victoria crescent agroecological zone exhibited the highest level of OTA contamination with mean concentration of 5.37 ± 0.08µg/kg, ranging from 2.63µg/kg to 6.55µg/kg while the lowest contamination with OTA was from western rangelands agroecological zone with mean concentration of 0.20 ± 0.10µg/kg and an interval of 0.20µg/kg to 7.61µg/kg. OTA contamination in Lake Albert crescent agroecological zone was 1.01 ± 0.10µg/kg and ranging from 0.03 to 6.79µg/kg. These results suggest the need for improved post-harvest management and a regulatory framework to ensure sustainable supply of safety and quality cocoa beans. This is the first study to report occurrence and contamination levels of aflatoxins and ochratoxin A in cocoa beans produced in Uganda. Cocoa beans from the three agroecological zones of Uganda were contaminated with aflatoxin and ochratoxin A albeit at considerably low concentration levels with most of cocoa beans found to be within recommended international food safety regulatory limits for ochratoxin A and total aflatoxins. The study underscores the need for mycotoxin regulatory framework, surveillance system and robust preventive strategies to ensure food safety, public health and promote access to high value international market. The study findings are important for future research and provide valuable insights for policy makers, regulatory bodies and cocoa value chain actors.