Influence of experimental parameters on the fluorescence response and recovery of the high-performance liquid chromatography analysis of fumonisin B1

Post-harvest interventions decrease aflatoxin and fumonisin contamination in maize and subsequent dietary exposure in Tanzanian infants: a cluster randomised-controlled trial

A cluster randomised controlled trial was performed in three agro-ecological zones of Tanzania to evaluate the effectiveness of locally available post-harvest mitigation strategies in preventing and reducing aflatoxin and fumonisin contamination in maize. A total of 300 children, each from one household, were randomly selected from 30 villages (intervention: n=15). The mitigation strategies focused on hand sorting (prior to storage and use), drying maize on mat/raised platforms, proper sun drying, application of storage insecticides and de-hulling before milling. Maize sample was collected from each household at harvest (baseline) and six months after harvest. Maize intake by each child, estimated using the 24 h dietary recall technique and its body weight measured using standard procedures were taken at six months after harvest. Aflatoxins and fumonisins in the maize samples were determined using HPLC. Follow-up (six month after harvest) data were available for 261 of the 300 households (intervention: n=136). Mean concentration of aflatoxins, or fumonisins was significantly (P<0.05) lower in the intervention than in the control group: intervention effects: μg/kg (95% confidence interval (CI)) -4.9 (-7.3,-2.5), and -405, (-647,-162), respectively. The difference corresponds to 83 and 70% for aflatoxins, and fumonisins, respectively. At the end of the intervention, aflatoxin and fumonisin estimated mean intakes were lower in the intervention than in the control group by 78 and 65%, respectively. Six months after harvest, prevalence of underweight in the intervention group was 6.7% lower (P=0.014) than in the control group. Mean weight-for-age Z-score difference between the groups was 0.57 (95% CI; 0.16,-0.98; P=0.007). Post-harvest practices are effective in preventing and reducing aflatoxin and fumonisin contamination in maize and subsequent dietary exposure to infants. The interventions may be applied in these and other communities with similar environmental conditions or agricultural practices that favour production of aflatoxin and fumonisins in food crops. The trial was registered at ClinicalTrials.gov identifier: NCT02438774.

Control of Fusarium verticillioides (Sacc.) Nirenberg and Fumonisins by Using a Combination of Crop Protection Products and Fertilization

Fusarium verticillioides is the most common fungal pathogen associated with maize ear rot in Tanzania. In a two-year trial, we investigated the efficacy of crop protection (insecticide and/or fungicide) and fertilizer (nitrogen and/or phosphorus) treatments in reducing the occurrence of F. verticillioides and its mycotoxins in maize grown in Tanzania. Seasonal differences were seen to have a substantial influence on the incidence and severity of insect infestation, Fusarium ear and kernel rot, biomass of F. verticillioides and contamination with fumonisins. With regard to the application of fertilizers, it was concluded that the impact on maize stalk borer injury, Fusarium symptoms and fumonisin levels was not significant, whereas crop protection significantly reduced maize damage. The application of an insecticide was most effective in reducing insect injury and as a result of the reduced insect injury the insecticide treatment also resulted in a significant decrease in Fusarium symptoms. In 2014, fumonisin levels were also significantly lower in maize treated with an insecticide. Additionally, significant positive correlations between insect damage and Fusarium symptoms were observed. In conclusion, this study clearly shows that application of an insecticide alone or in combination with a fungicide at anthesis significantly reduces insect damage and consequently reduces F. verticillioides infection and associated fumonisin contamination.

Risk of dietary exposure to aflatoxins and fumonisins in infants less than 6 months of age in Rombo, Northern Tanzania

Infants less than 6 months of age receiving foods other than breast milk are at a high risk of exposure to mycotoxins. We surveyed food intake and estimated the risk of exposures to aflatoxin and fumonisin mycotoxins for infants less than 6 months of age in Northern Tanzania. A total of 143 infants were progressively recruited and three follow-up visits were made at 1, 3 and 5 months of age. A 24-h dietary recall technique was used to estimate flour intake of infants who had been introduced to maize foods. Aflatoxins and fumonisins in the flours were analysed using high-performance liquid chromatography technique. Exposure to aflatoxins or fumonisins was estimated using the deterministic approach. By the age of 3 months, 98 infants had started taking food; 67 of them, maize flours at levels ranging from 0.57 to 37.50 g per infant per day (average 8 g per infant per day). Fifty-eight per cent of 67 maize flour samples contained detectable aflatoxins (range 0.33-69.47 μg kg(-1) ; median 6 μg kg(-1) ) and 31% contained detectable fumonisins (range 48-1224 μg kg(-1) ; median 124 μg kg(-1) ). For infants who consumed contaminated flours, aflatoxin exposure ranged from 0.14 to 120 ng kg(-1) body weight (BW) per day (all above the health concern level of 0.017 ng kg(-1) BW per day as recommended by the European Food Safety Agency) and fumonisin exposure ranged from 0.005 to 0.88 μg kg(-1) BW per day. Insignificant association was observed between exposure to fumonisins or aflatoxins and stunting or underweight. Reducing aflatoxin and fumonisin contamination of maize and dietary diversification can prevent infants and the public, in general, from exposure to the toxins.

Strategies to reduce exposure of fumonisins from complementary foods in rural Tanzania

Feeding infants with maize can expose them to fumonisin mycotoxins. We assessed fumonisin exposure from complementary foods in rural Tanzania and determined strategies to reduce the exposure. We conducted a cross-sectional study in four villages of Tarakea division, Northern Tanzania. We used a repeat 24-hour dietary recall to collect data of maize consumption as complementary food for 254 infants aged 6-8 months. Fumonisin concentrations in the maize were also estimated. Fumonisin exposure was assessed using @risk analysis software. With the software, several maximum fumonisin contamination and maize consumption patterns were combined in order to determine effective strategies for minimizing fumonisin exposure. Of the infants, 89% consumed maize at amounts up to 158g/person/day (mean; 43g/person/day±28). The maize was contaminated with fumonisins at levels up to 3201µgkg(-1) . Risk of fumonisin intake above the provisional maximum tolerable daily limit of 2µgkg(-1) body weight was 15% (95% confidence interval; 10-19). The risk was minimized when the maximum contamination was set at 150µgkg(-1) . The risk was also minimized when the maximum consumption was set at 20g/child/day while keeping the maximum contamination at the European Union (EU) maximum tolerated limit (MTL) of 1000µgkg(-1) . Considering the economical and technological limitations of adopting good agricultural practices in rural Tanzania, it is practically difficult to reduce contamination in maize to 150µgkg(-1) . We suggest adoption of the EU MTL of 1000µgkg(-1) for fumonisins in maize and reduction, by replacement with another cereal, of the maize component in complementary foods to a maximum intake of 20g/child/day.

Analysis of fumonisins B1 and B2 in spices and aromatic and medicinal herbs by HPLC-FLD with on-line post-column derivatization and positive confirmation by LC-MS/MS

Fumonisins are produced by the fungus Fusarium verticillioides, which are known to cause fatal diseases in some animals and humans. Here, we describe a sensitive, reproducible and reliable analytical method for the quantitative determination of fumonisins B(1) (FB(1)) and B(2) (FB(2)) in 112 spices and aromatic and medicinal herbs marketed in China. This method is based on high performance liquid chromatography and fluorescence detection (HPLC-FLD) coupled to a new on-line post-column derivatization using ortho-phthaldialdehyde with 2-mercaptoethanol and immunoaffinity column clean-up. Under the optimized experimental conditions, a complete separation of FB(1) and FB(2) was obtained using a Synergi C(18) column and a gradient elution at 0.8 mL min(-1) with methanol and 0.1 M phosphate buffer at pH 3.15. The limits of detection for FB(1) and FB(2) were both 40 μg kg(-1). Good recoveries were found for spiked samples with FB(1) and FB(2), ranging from 82.34% to 98.16% for FB(1) and from 72.58% to 97.10% for FB(2), with relative standard deviation (RSD) < 7.0%. 5 spices, 11 aromatic herbs and 96 medicinal herbs including 93 normal samples and 19 visibly moldy samples, which were spoiled artificially, were analyzed. The results showed that 8 (42.1%) visibly moldy samples and 8 (8.6%) normal samples were contaminated with FB(1) at mean contents of 129.0 and 165.9 μg kg(-1), and with FB(2) at 1745.0 and 256.8 μg kg(-1), respectively. Positive confirmation of detected samples was performed by liquid chromatography tandem electrospray ionization mass spectrometry (LC-ESI-MS/MS), using a triple quadrupole analyzer and operated in the multiple reaction monitoring mode.

Rapid determination of fumonisins B1 and B2 in corn by liquid chromatography-tandem mass spectrometry with ultrasonic extraction

A simple, sensitive, and reliable analytical method is developed for the rapid determination of fumonisin B(1) and fumonisin B(2) in corn by high-performance liquid chromatography-positive electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). Fumonisin B(1) and fumonisin B(2) are extracted from corn with methanol-water (3:1, v/v) by means of ultrasonic extraction, and directly injected into an LC-MS-MS system after centrifugation. Fumonisin B(1) and fumonisin B(2) are separated on a Zorbax Eclipse XDB-C(18) column with a solution of methanol-water-formic acid as the mobile phase. The method is validated with respect to linearity, accuracy, precision, specificity, and stability. Moreover, the method was applied to real samples and demonstrated to be suitable for the determination of fumonisin B(1) and fumonisin B(2) in corn. The total time required for the analysis of one sample was ~30 min.

Co-occurrence of fumonisins with aflatoxins in home-stored maize for human consumption in rural villages of Tanzania

This study determined maize-user practices that influence the presence of fumonisin and aflatoxin contamination of maize in food consumed in the rural areas of Tanzania. Samples of the 2005 maize harvest in Tanzania were collected from 120 households and examined for fumonisins and aflatoxins. Information on whether the maize was sorted to remove defective (visibly damaged or mouldy) maize before storage and whether the damaged and mouldy maize or the non-dehulled maize was used as food was also collected. In addition, the percentage of defective kernels in the samples was determined. Ninety per cent of the households sorted out defective maize, 45% consumed the defective maize and 30% consumed non-dehulled maize. In 52% of the samples fumonisins were determined at levels up to 11,048 microg kg(-1) (median = 363 microg kg(-1)) and in 15% exceeded 1000 microg kg(-1); the maximum tolerable limit (MTL) for fumonisins in maize for human consumption in other countries. Aflatoxins were detected in 18% of the samples at levels up to 158 microg kg(-1) (median = 24 microg kg(-1)). Twelve per cent of the samples exceeded the Tanzanian limit for total aflatoxins (10 microg kg(-1)). Aflatoxins co-occurred with fumonisins in 10% of the samples. The percentage defective kernels (mean = 22%) correlated positively (r = 0.39) with the fumonisin levels. Tanzanians are at a risk of exposure to fumonisins and aflatoxins in maize. There is a need for further research on fumonisin and aflatoxin exposure in Tanzania to develop appropriate control strategies.

Human exposure to fumonisins from home grown maize in Tanzania

Fumonisins contaminate maize worldwide resulting in unacceptable fumonisin exposures in people relying on maize as staple food. This study determined fumonisins B1 (FB1) and B2 (FB2) in maize from 120 rural households: 30 from each of four main maize producing regions of Tabora, Ruvuma, Iringa and Kilimanjaro in Tanzania in order to estimate total fumonisin (FB1 + FB2) exposures to adult individuals in the households. The average daily per capita maize consumption of 771 g, recommended by the Tanzania Food and Nutrition Centre (TFNC) for an adult relying on it as a main meal, and also average daily per capita maize consumptions of 129, 308 and 356 g documented for Tanzania, were used in the exposure estimation. The fumonisins were determined by HPLC using fluorescence detection. Total fumonisins exposure (µg/kg body weight (bw)/day) was determined by multiplying average daily per capita maize consumption (kg) by fumonisin level in maize (µg/kg) from a given household and then dividing by an average bw of an adult of 60 kg. Of the 120 samples, 52% were contaminated with fumonisins at levels of up to 11,048 µg/kg (median; 363 µg/kg). Based on the recommended maize consumption of 771 g/person/day, fumonisin exposures to adult individuals in 38% of the households would exceed the provisional maximum tolerable daily intake (PMTDI) of 2 µg/kg bw, recommended by the Joint FAO/WHO Expert Committee on Food Additives. At the least documented maize consumption of 129 g/person/day, fumonisin exposures in 16% of the households were still above the PMTDI. Reduction of the maize consumption level to 40 g/person/day is an impractical, and reduction of the maximum contamination level to 155 µg/kg is a possibly practical, option for effective minimisation of fumonisin exposures in these communities. A relatively larger study is needed in order to generate comprehensive data for the formulation of appropriate strategies to minimise fumonisin exposures in Tanzania.

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B1 production of Fusarium verticillioides and F. proliferatum on corn. Part I: The effect of initial headspace carbon dioxide concentration

The effect of modified atmospheres on the growth and fumonisin B(1) production of Fusarium verticillioides and Fusarium proliferatum on corn is presented in a series of two papers. In this, the first part, the effect of initial headspace (IH) carbon dioxide concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was evaluated. It was observed that at all a(w) values studied, increase in the IH CO(2) concentration generally resulted in a decrease in the colony growth rate (g, mm day(-1)) and maximum colony diameter (D(max), mm) and an increase in the lag phase duration (lambda, day). Although both a(w) and IH CO(2) concentration had significant and synergistic effects on g, a(w) had the largest effect. As little as 10% IH CO(2) completely inhibited the production of fumonisin B(1) by F. verticillioides. F. proliferatum was more resistant and required 40, 30 and 10% IH CO(2) at a(w) 0.984, 0.951 and 0.930, respectively, to completely inhibit fumonisin B(1) production. These results demonstrate that modified atmospheres containing high CO(2) levels could potentially be employed for the protection of corn from fungal spoilage and mycotoxin contamination during the post-harvest period.

Interaction of water activity and bicarbonate salts in the inhibition of growth and mycotoxin production by Fusarium and Aspergillus species of importance to corn

The combined effects of water activity (a(w)) and ammonium/sodium bicarbonate on growth and mycotoxin production in corn by Fusarium and Aspergillus species were investigated. Interaction was observed between the salts and a(w) on the colony growth rates and lag phase durations of all isolates. Growth stimulation at low salt levels was observed only for the Fusarium isolates as the fastest growth of F. verticillioides and F. proliferatum occurred at levels of 0.1-0.2 and 0.5% ammonium and sodium bicarbonate, respectively. Although the complete inhibition of the growth of the Fusarium and Aspergillus isolates investigated took place at a level of 1% ammonium bicarbonate as much as 4% sodium bicarbonate failed to completely inhibit the growth of the Aspergillus isolates. Increase in concentration of either salt generally resulted in large reductions of both fumonisin B(1) and aflatoxin B(1) production. According to the sensorial analysis performed, corn treated with up to 1% ammonium bicarbonate was still acceptable for consumption, whereas corn treated with at least 2% sodium bicarbonate was determined to be sensorially unsuitable. Ammonium bicarbonate can be concluded to be more suitable for protecting stored corn from fungal contamination as it was capable of completely inhibiting both growth and mycotoxin production of the Fusarium and Aspergillus isolates of most importance to corn at levels that were still sensorially acceptable. Therefore ammonium bicarbonate could possibly be applied as a cheap and easy to apply treatment for use in resource limited developing countries.

The influence of modified atmospheres and their interaction with water activity on the radial growth and fumonisin B(1) production of Fusarium verticillioides and F. proliferatum on corn. Part II: The effect of initial headspace oxygen concentration

This paper is the second in a series of two that describe the effect of modified atmospheres on the growth and mycotoxin production of Fusarium verticillioides and Fusarium proliferatum on corn. In this part, the effect of initial headspace (IH) oxygen concentration and its interaction with water activity (a(w)) on growth and fumonisin B(1) production was investigated. In addition, the impact of vacuum packaging and in-cooperation of O(2) scrubbing sachets was also studied. It was observed that at all a(w) values studied, reduction of IH O(2) concentration from 20 to 2% had no significant effect on the colony growth rate (g, mm d(-1)) and lag phase duration (lambda, d). However, g and lambda were positively and negatively correlated to a(w). The IH O(2) concentration was determined to have a a(w) dependent effect on the oxygen consumption rate. Although the maximum colony diameter (D(max), mm) decreased with the reduction of the IH O(2) level, the greatest mycelial density occurred at 10% IH O(2) for both isolates. This observation was accompanied by a trend of a decrease in the value of the IH O(2) level at which the most fumonisin B(1) was produced from 15 to 5% when the a(w) was decreased from 0.976 to 0.930 for F. verticillioides. For F. proliferatum the optimum conditions for fumonisin B(1) production shifted from 20% at a(w) 0.976 to 10% at both 0.951 and 0.930. Vacuum packaging and the in-cooperation of O(2) absorbing sachets completely inhibited the growth of both isolates. These results together with those reported in Part I of the study indicate that O(2) should preferably be completely excluded from modified atmospheres that are employed to protect stored corn from fungal growth and mycotoxin production.