Effect of Climate and Type of Storage Container on Aflatoxin Production in Corn and its Associated Risks to Wildlife Species

Abstract

The effects of grain storage containers on aflatoxin production, and the relationship between the level of aflatoxin and the number and weight of fluorescing kernels were determined in corn (Zea maize) stored in controlled climate regimes. Two hundred and forty 100-g samples were held up to 3 mos using four types of storage containers placed in four climates. Storage containers included corn placed in metal cans, paper bags, plastic bags, and paper bags placed in plastic bags. Climates were constant during the duration of the project and included a combination of temperatures and humidities. Temperatures were 29-32 C and 14-18 C; relative humidities were 85-88% and 35-40%. In addition, corn was exposed to environmental conditions conductive for aflatoxin production and 100 g samples were randomly collected, examined under ultraviolet light for fluorescence, and then quantified for aflatoxin levels. Corn samples tested negative for aflatoxin at the beginning of the project. Main (i.e., container, climate, and month) and interactive effects were not observed. Mean levels of aflatoxin ranged from 0 to 151 microg/kg. Aflatoxin was produced regardless of type of storage container, time of storage, and climatic conditions; however, only 8% of the samples produced aflatoxin levels that exceeded 50 microg/kg. Fluorescing corn ranged from 0 to 19 kernels per sample, while aflatoxin levels ranged from 0 to 1,375 microg/kg for the same samples. No relationships were found between the number and weight of fluorescing kernels of corn and aflatoxin levels. The black light test yielded a false negative rate of 23% when in fact the aflatoxin concentrations exceeded 50 microg/kg. Therefore, quantifying fluorescing grain under UV light should not be considered a feasible alternative for aflatoxin testing of grain intended for wildlife.

<b>Occurrence of <i>Aspergillus</i> sp., <i>Fusarium</i> sp., and aflatoxins in corn hybrids with different systems of storage

“…As shown in Figure 2 (a), between four and seven months of storage (November 2012to February 2013, the temperature exceeded 20.5ºC. According to Thompson and Henke (2000), temperatures above 21ºC are propitious to the germination of spores and to the mycelial growth of Aspergillus sp.…”

“…The average temperatures were 15.2 and 23°C for winter and summer storage, respectively. According to Thompson and Henke (2000), A. flavus and A. parasiticus can grow and produce aflatoxins in temperatures above 21°C. Additionally, Arrus et al (2005) verified an increase of Aspergillus sp.…”

“…Many studies assessed the physical-chemical properties (Costa, Faroni, Alencar, Carvalho, & Ferreira, 2010) and health concerns of corn during storage (Hirooka et al, 2007;Mohale et al, 2013;Santin, Gutokoski, Eichelberger, Portella, & Durigon, 2009;Thompson & Henke, 2000). However, most of these studies evaluated storage alternatives used at large scales and did not consider the rudimentary systems still in use on small farms in developing countries such as Brazil.…”

“…Among the mycotoxins detected in corn, toxic secondary metabolites that are produced by filamentous fungi and aflatoxins (B 1 , B 2 , G 1 and G 2 ) that are produced by several species of Aspergillus have great importance for the toxic effects to humans and animals and because of the carcinogenic, mutagenic and teratogenic properties (Moreno et al, 2009;Thompson & Henke, 2000). Aflatoxins are a worldwide economic problem because of the effects on the export of grains and livestock production (Rocha et al, 2009).…”

Comparison of thin-layer chromatography, spectrofluorimetry and bright greenish-yellow fluorescence test for aflatoxin detection in corn

“…(Table 1). Thompson and Henke (2000) reported no relationship between the number and weight of fluorescing corn kernels and aflatoxin levels. Interfering compounds in corn matrix, when excited by UV light can absorb and emit fluorescent light with wavelengths similar to aflatoxins, yielding false-positive results.…”