UTILIZATIION OF ORGANIC ACID FOR INHIBITING AFLATOXIN PRODUCED BY Aspergillus flavus IN STORED YELLOW CORN

Abstract

The effect of organic acid mixtures on the growth of Aspergillus flavus and subsequently on the production of aflatoxins B1, B2, G1, G2 and total aflatoxins in yellow corn at two moisture levels, was investigated. Yellow corn grains was calibrated to moisture levels 15 and 20% and treated with combined application of propionic acid + acetic acid + formic acid at ratios 1:1:2 (mixture1), 1:2:2 (mixture2) and 1:2:3 (mixture3). A preliminary stepwise protocol starting from 0.2% to 1.0% concentration was used to determine the concentration of organic acid mixtures that can inhibit growth of A. flavus in yellow corn during 21 days. Then, the chosen concentrations were used in the main experiment which lasted 60 days. In yellow corn with 15% moisture, one concentration (0.2%) was used to the main trial. When moisture was raised to 20%, two concentrations were used (0.8 and 1.0%) to the main experiment. The trial included two groups of treatments, with and without A. flavus infection then, stored at room temperature 30 oC and 25 oC for 60 days. Results showed that A. flavus production increased with increasing moisture level, but decreased as the concentration of organic acid increased. Total fungal count increased during the whole period of the experiment in the control groups. At all storage conditions, mixture 3 showed less fungal inhibity effect. raising moisture content of yellow corn was up to 20%, mixture 2 was found to be the best mold inhibitor at a concentration of 0.8%. Incubation at 25oC was more effective than that at room temperature to reduce total aflatoxins. It could be concluded that, using 1.0 % of mixture 1 and mixture 2 as preservatives inhibited both growth of A. flavus, and aflatoxin production in yellow corn stored whether at 25°C or ats room temperature during the 21 days of storage.