Abstract
Occurrence of mycotoxins in foods poses a serious health concern all over the world. Aflatoxin B1 (AFB1) is the most toxic, with widest occurrence in various foods, but mainly in cereals and nuts and its accumulation depends on substrate and environmental factors. This study investigated the how physical status (milling) of maize kernels and atmospheric conditions (aeration, moisture and temperature) affect production of aflatoxin B1 by Aspergillus flavus (ATCC 28862). Intact kernels and flour were incubated for up to 20 days in open and partially sealed petri dishes under controlled temperatures of 25 ºC, 30 ºC and 37 ºC and initial moisture contents of 27%, 22%, 18%, 15% and 12%. It was found that on average, significantly higher (p < 0.05) aflatoxin B1 level was accumulated in intact kernels (145.7 µg/kg) as compared to milled kernels (2.2 µg/kg). Also, none of the samples incubated under partially sealed conditions, compared to up to 100% of the samples incubated in open atmosphere had detectable levels of aflatoxin B1 after 20 days. Fungal growth was not affected by milling or aeration, but sporulation was low at 37 ºC and high at 25 ºC and 30 ºC. The findings of this study provide baseline information on how conditions can be modified to control postharvest accumulation of aflatoxin B1 in cereals.
Highlights
Storage environment such as humidity, aeration, and ambient temperature are among factors which influence fungal infection and mycotoxin accumulation in stored food products (Holmquist et al, 1983, Mutegi et al, 2013)
This study investigated the how physical status of maize kernels and atmospheric conditions affect production of aflatoxin B1 by Aspergillus flavus (ATCC 28862)
Maize meals are prepared from maize kernels processed in different forms including intact kernels, dehulled, crushed, milled, fermented and the methods vary between communities (Gwirtz and Garcia-Casal, 2014)
Summary
Storage environment such as humidity, aeration, and ambient temperature are among factors which influence fungal infection and mycotoxin accumulation in stored food products (Holmquist et al, 1983, Mutegi et al, 2013). The method, in addition of controlling pests is reported to have positive impacts on mycotoxins formation by limiting oxygen availability to the contaminating fungi (Tubbs et al, 2016). Another important factor in achieving proper storage is the form in which the crops, especially grains. In most African societies is stored either as intact kernels, dehulled, crushed or milled to flour. The effects of these different physical forms on mycotoxin formation are not well established (Gwirtz and Garcia-Casal 2014). Laboratory settings for moisture level and temperature were tested in order to understand how the factors should be maneuvered when setting similar or related experiments
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