Updated profile of aflatoxin and Aspergillus section Flavi contamination in rice and its byproducts from the Philippines

Abstract

Our goal was to develop an updated profile of aflatoxin (AF) and AF-producing fungi contamination in rice and its byproducts from the Philippines. The total AF levels in 78 samples of polished and brown rice, determined by an immunoaffinity column clean-up method coupled with HPLC (detection limit: 25 ng/kg), ranged from <0.025–2.7 µg/kg (mean of positive samples: 0.37 µg/kg) and 0.03–8.7 µg/kg (mean of positive samples: 2.7 µg/kg), respectively. The incidence (% of positive samples) of AF in polished and brown rice were 94% and 100%, respectively. The AF levels in polished rice imported from Thailand and Vietnam were approximately 20% of the levels found in locally produced polished rice. AF levels decreased as the rice progressed through the various stages in milling. Fungi recovered include toxigenic Aspergillus flavus and A. parasiticus with an incidence ranging from 14% in rice bran to 78% in rough rice and producing <0.025−6200 µg/kg total AF in in vitro cultures on rice. All samples of rice bran and rice hull contained AF at levels ranging from 0.27–11 µg/kg. The estimated potential daily intake of AFB1 from rice is between 0.1 and 7.5 ng/kg of body weight/day, the mean of which is 1.0 ng representing 9.1–5.3 times the estimated tolerable daily intake for AFB1 reported to date for Asia. Thus, Filipinos have a potentially high risk of exposure to AF that can be easily controlled through proper post-harvest handling and storage of rice and its byproducts.