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Distribution of Aflatoxin B1, B2, G1, and G2 in Various Fractions of Rice

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2015 ASABE Annual International Meeting  152190260.(doi:10.13031/aim.20152190260)
Authors:   HouMin Zhong, Griffiths G Atungulu, Bennie J. Bench, Shantae Wilson, Vy T. Nguyen
Keywords:   Amelioration, Aflatoxin, Rice, Milling.

Abstract. Aflatoxin, especially the Aflatoxin B1, is a known carcinogen that poses health hazards to consumers of grain and grain co-products. At the present, United States Food and Drug Administration (FDA) regulates the level of aflatoxin B1 at 20 ppb or less for grain destined for human consumption, and 300 ppb or less for feed. Beyond the set limit, the grain has to be disposed which represents a significant economic loss to the producers. Contaminated grain could be processed to reduce concentrations of aflatoxin to levels that meet other end-uses. The objective of this study was to investigate the potential to ameliorate aflatoxin-contaminated rough rice by milling treatments. Samples of long-grain, pureline rough rice (cv. Cheniere), naturally contaminated with aflatoxin, were used in this study. The initial concentration of aflatoxin B1, B2, G1, and G2 in the rough rice were determined as 27, 9.5, 2.5, and 0 ppb, respectively. The rough rice samples were dehulled and milled at three milling degrees (30, 45, and 60 s of millings). The concentrations of Aflatoxin B1, B2, G1, and G2 in various constituents of the rice such as hull, brown rice, and milled rice and bran obtained after different milling durations were determined using Ultra-Performance Liquid Chromatography (UPLC) coupled to Triple Quad Detector. Two Multiple Reaction Monitorings (MRMs) were utilized to provide a qualitative and quantitative assessment of each Aflatoxin. Based on the results, aflatoxin levels decreased as milling duration increased. For brown rice, aflatoxin B1 and B2 concentrations were at 29.5 ppb and 8.5 ppb, respectively. Milling rice samples for 60 s reduced the concentration of aflatoxin B1 5-fold and completely removed all the aflatoxin B2. Aflatoxins were found mostly in the rice bran, and were highly concentrated especially in the outer bran layers as evidenced by concentrations of aflatoxin B1 (214 ppb; 121 ppb) and B2 (16 ppb; 9ppb) after 30 and 60 s of milling, respectively. Aflatoxin G1 was only detected in rough rice and brown rice, but not after 30, 45 and 60 s of milling. Aflatoxin G2 was not detected in any of the rice constituents analyzed. These findings could benefit the rice industry by helping to find an effective strategy to utilize aflatoxin contaminated rice.

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