Aflatoxins and aflatoxigenic fungi in rice and its byproducts

Abstract

This report gives a retrospective of studies done on aflatoxins and aflatoxigenic fungi in rice and its by-products. Previous studies on rice employed analytical methods with detection limits ranging from 0 .1 to 5μg/kg, which could mean that lower levels were overlooked, thus, underestimating the actual incidence of aflatoxins in the commodity. Aflatoxin production in rice is relatively minimal. However, high aflatoxin levels have been found in samples from some countries in Asia and Africa, which can be attributable to inadequate postharvest system. Incidence of aflatoxins in more than 2800 samples of rice and its products surveyed all over the world appears to have increased from 7% in the 70s to about 31% from 2000 onwards. Levels of AFB1 and total AF in samples analyzed were mostly beyond European Union regulatory limits; some even have levels above 20μg/kg, the amount of aflatoxins allowed in foods by Codex Alimentarius. Incidence of aflatoxigenic species, particularly A. flavus and A. parasiticus, in rice and its by-products appears to be concentrated in the tropical and subtropical regions, where prevailing environmental conditions are conducive to their growth. Due to increasing stringency of regulatory limits, there is a need to develop more sensitive methods that can detect the lower levels of aflatoxins found in rice and its by-products and ascertain the extent of contamination in these commodities. In order to regulate these commodities, continued monitoring is necessary to provide data that can serve as basis for exposure assessment studies. Other urgent areas for research are those of improved and integrated approaches to control aflatoxins and aflatoxigenic fungi at all stages of production and marketing.