Influence of storage environment on maize grain: CO₂ production, dry matter losses and aflatoxins contamination

Abstract

Poor storage of cereals such as maize can lead to both nutritional losses and mycotoxin contamination. The aim of this study was to examine the respiration of maize either naturally contaminated or inoculated with Aspergillus flavus to examine whether this might be an early and sensitive indicator of aflatoxin contamination and relative storability risk. We thus examined the relationship between different interacting storage environmental conditions (0.80-0.99 water activity (aw) and 15-35°C) in naturally contaminated and irradiate maize grain + A. flavus on relative respiration rates (R), dry matter losses (DMLs) and aflatoxin B1 and B2 (AFB1-B2) contamination. Temporal respiration and total CO2 production were analysed by GC-TCD, and results used to calculate the DMLs due to colonisation. Aflatoxins (AFs) contamination were quantified at the end of the storage period by HPLC MS/MS. The highest respiration rates occurred at 0.95 aw and 30-35°C representing between 0.5-18% DMLs.Optimum AFs contamination was at the same aw at 30°C. Highest AFs contamination occurred in maize colonised only by A. flavus. A significant positive correlation between %DMLs and AFB1 contamination was obtained (r=0.866, p<0.001) in the irradiated maize treatments inoculated with A. flavus. In naturally contaminated maize + A. flavus inoculum loss of only 0.56% DML resulted in AFB1 contamination levels exceeding the EU legislative limits for food.This suggests that there is a very low threshold tolerance during storage of maize to minimise . Please refer to any applicable publisher terms of use.2 AFB1 contamination. This data can be used to develop models which can be effectively used in enhancing management for storage of maize to minimise risks of mycotoxin contamination.

Three-Dimensional Study of F. graminearum Colonisation of Stored Wheat: Post-Harvest Growth Patterns, Dry Matter Losses and Mycotoxin Contamination

“…The low respiration levels found in the bottom-centre colonisation at 0.95 a w may thus have been due to lower oxygen levels in the intergranular spaces and the more stressful water availability treatment. Overall, the present results show that fungal colonisation rates can be accurately estimated by the amount of CO 2 produced in different stored cereals [3,5,27,28].…”

Carbon dioxide production as an indicator of Aspergillus flavus colonisation and aflatoxins/cyclopiazonic acid contamination in shelled peanuts stored under different interacting abiotic factors

“…Similar CO2 production levels were found at 30 and 35 o C in both naturally (2079 and 2281 mg CO2 kg -1 h -1 ), and inoculated (2274 and 2096 mg CO2 kg -1 h -1 ). In other cereal commodities, R for shelled peanuts was also optimum at 0.95 aW in paddy rice, brown rice and maize when inoculated with A. flavus at 30-35°C (Garcia-Cela et al, 2019;Martín Castaño et al, 2017b). The baseline data in the driest treatments were different for each cereal type because of the inherent cereal respiration and differences in the natural contamination with mycobiota and toxigenic fungi.…”

“…Indeed, because peanuts are hygroscopic they will often reabsorb moisture from the environment when post-harvest management is not effectively controlled. In previous studies with cereals, mycotoxin contamination of about 1% resulted in type A and B trichothecenes, zearalenone (both in wheat) and fumonisins toxin levels (maize) exceeded the EU legislative limits (Mylona and Magan, 2011;Mylona et al, 2012b;2019). For fatty acid rich nuts such as hazlenuts, Mylona (2012a) found that only 0.4% DML resulted in AFB1 contamination exceeding the EU limits.…”

“…Previously, DML values as low as 0.04, 1 and 2% indicated impacts on seed germination and risk of mycotoxin contamination in the context of the EU legal maximum limits Garcia-Cela et al, 2019;Lacey et al, 1994;Martín Castaño et al, 2017ab;Mylona et al, 2012b;Mylona and Magan, 2011;White et al, 1982). However, very little data is available on nuts, especially peanuts, although studies by Mylona (2012a) examined A. flavus and CO2 production in hazelnuts, showing that very small DMLs resulted in aflatoxin B1 (AFB1) contamination exceeding the EU legislative limits.…”

“…Recent studies have shown that changes in CO2 production during storage of cereals, including maize, wheat, oats and rice can be used as an indicator of DML, as well as the relationship with mycotoxin contamination Garcia-Cela et al, 2019;Martín Castaño et al, 2017ab;Mylona et al, 2012 ab;Mylona and Magan, 2011). In these studies it was found that it is possible to use the progressive increase in the aerobic respiration rate under increasingly conducive interacting abiotic factors.…”