Natural occurrence of aflatoxins and toxigenic fungi in rice bran oil and de-oiled bran

Abstract

Samples of crude- and refined- rice bran oil and de-oiled bran collected from mills and local market places were analysed for the presence of aflatoxins B1 and the causal fungi. Out of 20 crude rice bran oil and 20 refined rice bran oil samples analysed, 15 and 6 samples, respectively were positive for aflatoxins B1. The aflatxoin B1 in the rice bran oil samples were in the range of trace to 956 ppb and averaged 618 ppb. Out of 30 samples analysed, 20 samples of de-oiled bran were positive and the toxin level ranged from 7 to 144 ppb with an average of 33 ppb. The storage fungi including toxigenic fungi present in the rice bran oil and de-oiled bran samples were Aspergillus glaucus, A. flavus, A. niger, A . nidulans, A. candidus, A. fumigatus, and Penicillium spp. and Gliocladium viride. In the rice bran oil samples, the fungi found were less in number (1 one to 14 cfu/g) with an average of 2 cfu/g. While, in the de-oiled bran, it was 1 to 130 X 103 cfu/g with an average of 33 X 103 cfu/g which include toxigenic A. flavus. About 60% of A. flavus from crude rice bran oil samples and 66.7% of A. flavus strains isolated from de-oiled bran samples were positive for aflatoxin production. Keywords: Aflatoxins, mycotoxins, storage fungi, Aspergillus flavus, rice bran oil, de-oiled rice bran.