Dietary risk assessment of selected organophosphorus and pyrethoid pesticide residues in fresh harvested tomatoes at Makambako Town, Njombe region, Tanzania.

This study aimed to assess the levels of selected pesticides residues in harvested tomatoes and their associated dietary risks to consumers at Makambako Town in Njombe region, Tanzania. Forty-two fresh tomatoes were sampled among tomato farmers during harvesting season and extraction of analytes was done using QuEChERS method and analysed by Gas Chromatography-Mass Spectrometer. Residues of chlorpyrifos, profenofos, gamma cyhalothrin and cypermethrin were alternatingly detected in 78.51% of samples. The average concentrations of residues were 0.014, 0.056, 0.003 and 0.2 mg/kg for chlorpyrifos, profenofos, gamma cyhalothrin and cypermethrin and were all below their respective Codex MRLs. The highest concentration was 0.718 mg/kg for cypermethrin, above the Codex MRL of 0.2 mg/kg. The hazard indexes indicate no potential health hazards to the general population due to the lifetime consumption of fresh tomatoes from the study area. Periodic monitoring of residue levels of pesticides in vegetable fruits, including tomatoes, is recommended.

The Influence of Weather on the Occurrence of Aflatoxin B1 in Harvested Maize from Kenya and Tanzania.

A study was conducted using maize samples collected from different agroecological zones of Kenya (n = 471) and Tanzania (n = 100) during the 2013 maize harvest season to estimate a relationship between aflatoxin B1 concentration and occurrence with weather conditions during the growing season. The toxins were analysed by the ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. Aflatoxin B1 incidence ranged between 0-100% of samples in different regions with an average value of 29.4% and aflatoxin concentrations of up to 6075 µg/kg recorded in one sample. Several regression techniques were explored. Random forests achieved the highest overall accuracy of 80%, while the accuracy of a logistic regression model was 65%. Low rainfall occurring during the early stage of the maize plant maturing combined with high temperatures leading up to full maturity provide warning signs of aflatoxin contamination. Risk maps for the two countries for the 2013 season were generated using both random forests and logistic regression models.

Curcumin-based photosensitization inactivates Aspergillus flavus and reduces aflatoxin B1 in maize kernels.

Different methods have been applied in controlling contamination of foods and feeds by the carcinogenic fungal toxin, aflatoxin, but nevertheless the problem remains pervasive in developing countries. Curcumin is a natural polyphenolic compound from the spice turmeric (Curcuma longa L.) that has been identified as an efficient photosensitiser for inactivation of Aspergillus flavus conidia. Curcumin mediated photoinactivation of A. flavus has revealed the potential of this technology to be an effective method for reducing population density of the aflatoxin-producing fungus in foods. This study demonstrates the influence of pH and temperature on efficiency of photoinactivation of the fungus and how treating spore-contaminated maize kernels affects aflatoxin production. The results show the efficiency of curcumin mediated photoinactivation of fungal conidia and hyphae were not affected by temperatures between 15 and 35 °C or pH range of 1.5-9.0. The production of aflatoxin B1 was significantly lower (p < 0.05), with an average of 82.4 µg/kg as compared to up to 305.9 µg/kg observed in untreated maize kept under similar conditions. The results of this study indicate that curcumin mediated photosensitization can potentially be applied under simple environmental conditions to achieve significant reduction of post-harvest contamination of aflatoxin B1 in maize.

Tools for Defusing a Major Global Food and Feed Safety Risk: Nonbiological Postharvest Procedures To Decontaminate Mycotoxins in Foods and Feeds.

Mycotoxin contamination of foods and animal feeds is a worldwide problem for human and animal health. Controlling mycotoxin contamination has drawn the attention of scientists and other food and feed stakeholders all over the world. Despite best efforts targeting field and storage preventive measures, environmental conditions can still lead to mycotoxin contamination. This raises a need for developing decontamination methods to inactivate or remove the toxins from contaminated products. At present, decontamination methods applied include an array of both biological and nonbiological methods. The targeted use of nonbiological methods spans from the latter half of last century, when ammoniation and ozonation were first used to inactivate mycotoxins in animal feeds, to the novel techniques being developed today such as photosensitization. Effectiveness and drawbacks of different nonbiological methods have been reported in the literature, and this review examines the utility of these methods in addressing food safety. Particular consideration is given to the application of such methods in the developing world, where mycotoxin contamination is a serious food safety issue in staple crops such as maize and rice.