Mycology and effects of dehauling local Oryza Sativa for human consumption on total aflatoxins within some parts of Kaduna metropolis

Abstract

Aflatoxins are the most toxic food contaminant and their presence in Oryza Sativa could have a great toxic effect on humans and animals health. The aim of this study was to isolate aflatoxigenic moulds from dehauled Oryza sativa and to assess the effects of small scale mechanized and traditional wooden pestle and mortar processing methods on aflatoxins. Standard techniques was employ to screen for moulds using potato dextrose agar and aflatoxigenic strains using Yeast extract sucrose agar (YESA) modified with 0.3% cyclodextrin and 0.6% sodium desoxycholate (YCSD). The total aflatoxin was determined using enzyme-linked immunosorbent assay (ELISA). Proximate values were also determined using standard techniques. The mould counts for the processed samples were lower than that of undehauled Oriza sativa. The percentage moisture was relatively low (9.69 and 9.79 %) for both small scale mechanized and pestle and mortar processing techniques respectively. Ash content of Oryza sativa obtained through pestle and mortar processing method presented higher level (0.74 %dm) compared to small scale mechanized technique (0.48 %dm). Aspergillus flavus had the highest frequency of occurrence. While thirty nine (39.0 %) of the total samples collected was contaminated with aflatoxigenic moulds, seventeen (17.0 %) represent prevalence of aflatoxin contamination. It was understood from this work that wooden pestle and mortar processing retains higher total aflatoxin level than small scale mechanized technique. The small scale mechanized technique is better but can further be standardized to solve the issue of drying after boiling raw Oryza sativa for dehauling.