Varietal differences in accumulation of aflatoxin B1 in Indian rice cultivars

Rice (paddy) seeds are known to be colonised by Aspergillus flavus in the field or under storage conditions and contaminated with aflatoxins which have impact on human and animal health. In this study, we investigated the varietal differences in 30 Indian healthy rice cultivars used for human consumption (15 normal and 15 basmati) for accumulation of aflatoxin B-1 (AFB(1)) after inoculation with aflatoxin-producing A. flavus (DRAf 009). Significant varietal differences in AFB(1) accumulation were observed in normal and basmati rice cultivars. Comparatively, the accumulation of AFB(1) is higher in normal cultivars, ranging from 3-628 mu g/kg, than in basmati cultivars, ranging from 0.2-7.2 mu g/kg. The highest accumulation of AFB(1) in normal cultivars was observed in PR 106 (628 mu g/kg) and the lowest in IR 64 (3 mu g/kg). In basmati rice cultivars, the highest accumulation of AFB(1) was observed in Ranbir basmati (7.2 mu g/kg) and the lowest in Vasumati (0.2 mu g/kg). All these cultivars were evaluated for their total phenolic content (TPC) in rice bran using the Folin-Ciocalteau method. The results indicated that the TPC of normal and basmati cultivars was in the range of 1.96-2.45 and 2.13-2.65 mg gallic acid equivalent (mg/g of bran), respectively. This study may be used as a basis to develop A. flavus resistant rice cultivars and proper storage structures to produce aflatoxin-free rice. This is the first report on the evaluation of various rice cultivars for accumulation of AFB(1) after inoculation with A. flavus.