Changes in Aflatoxins Contents of the Maize (Zea Mays L.) Stored in Clay Granaries with use of Biopesticides from Rural Conditions and Estimation of their Intake
Abstract
Maize protection without any risks for human health and environment concerns might be v alued on alternative uses of pest control methods that do not only rely on synthetic insecticides. A combination of leaves derived from Lippia multiflora Moldenke and Hyptis suaveolens Poit. Benth were tested for their protective effect on the aflatoxins l evels of maize cobs and grains stored in traditional and improved granaries in Côte d’Ivoire. Thus, 4 aflatoxins (B 1, B2, G 1 and G 2) were determined with high performance liquid chromatography according to the official method of AOAC. Results showed presen ce of afltatoxins in 58% of samples, and specifically aflatoxin B1 from half the samples, with rather higher levels than the reference values of the European Union. The levels of aflatoxins B 1, B2, G 1 and G 2 resulted from both maize cobs and grains treated with biopesticides (from 0.06 -0.53 µg/kg to 2.18 -50.70 µg/kg) were significantly lower than those recorded with untreated maize of control granaries (ranging from 0.06 -0.53 µg/kg to 12.48 -346.15 µg/kg). In the treated maize, the aflatoxins levels increase d slightly during 6 months of storage, while the untreated maize cobs were with significant increasing of the same toxins traits month after month. For each stage, aflatoxins levels of maize cobs and grains did not differ whether they are treated in tradit ional or improved granaries with both plant materials.
The estimated risk of exposure in aflatoxins, specifically in total aflatoxins and AFB 1, deriving with intakes of maize stored for 6 months are respectively 114.37 ±2.2 ng/kg body weight/day and 36 .21±0.11 ng/kg body weight/day for the untreated granaries and 7.15±0.04 ng/kg body weight/day and 2.12±0.17 ng/kg body weight/day for the treated granaries . These levels are strongly higher than the maximal Reference Value ( 0.15 pg/kg body weight/day ) tolerate d for Toxicity exposure. Therefore, it’s necessary to sensitize, on a larger scale, actors of maize path, namely farmers, retailers, processers and consumers about such mycotoxins in maize products for providing health safety to Ivorian populations.
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Introduction
Maize (Zea mays L., Poaceae) has a substantial contribution in the diets of rural and urban populations (Baoua et al., 2014). In Côte d’Ivoire, this crop is generally cultivated by small-scale farmers and widely grows across various ecological zones, from the northern savannah till the rain forest belt in the south (Kouakou et al., 2010), with a yield of 654,738 tons in 2012/2013 from 327,800 ha of total planted area (N'da et al., 2013). Maize allows diverse dishes such as porridge, couscous or dense paste (tô) eaten with sauce and is totally domestically consumed at the rate of 28.4 per capita (Beugre et al., 2014).
A recent USAID study highlighted the maize sector’s concerns in Western Africa, one of which is the post-harvest storage (Boone et al., 2008). In fact, maize stored in warm and humid conditions and with pests pressure is most prone to infection by toxigenic agents, especially Aspergillus, Fusarium and Penicillium, and therefore to mycotoxins contamination (Sekiyama, 2005).
Aflatoxins are the most current mycotoxins involving with maize contamination (Hell et al., 2002). Among all aflatoxins groups, the aflatoxin B is the most widespread accounting both toxicology and occurrence traits. It is a human carcinogen 1 and has been classified as a group 1 carcinogen by the International Agency for Research on Cancer (IARC, 2002). Apart from toxicity hazards to human and animals, aflatoxins cause reduction in nutritional properties, seed viability, grinding quality, sanitary quality and trading value of cereals (Liu et al., 2006). The Food and Agriculture Organization of the United Nations (FAO) stated that at least 25% of the world’s cereal grains are contaminated by mycotoxins, including aflatoxins (FAO, 2004). Such a constraint leads unfortunately to disposal of large amounts of crops stored in inadequate conditions. Maize susceptibility to contamination by toxigenic molds and mycotoxins production has been documented in West African countries such as Côte d’Ivoire, Benin and Nigeria (Sangaré-Tigori et al., 2005; Fandohan et al., 2005; Adetunji et al., 2014).
Thus, proper conditions of maize storage could allow significant improvement in the national farmer’s economy by controlling the losses. In fact, the storage technologies have major roles upon the final quality of the resulted grains.
Ensuring optimal efficiency of the storage technologies is highly crucial for the safety of the stored grains and for the consumer’s health. Common pests controlling system of stored products is with the application of synthetic contact insecticides (Nukenine et al., 2013) despite many risks on the health of users and consumers and environmental pollution (Regnault-Roger, 2008). Nevertheless, other methods of storage and preservation could be improved for finding alternatives in uses of synthetic pesticides for the post-harvest losses reduction.
The current research deals with statement of maize storage structure that would rely on more efficiency, economical feasibility, environmental safety and could benefit to farmers. The study assesses effects of two local plants, namely Lippia multiflora and Hyptis suaveolens, deriving with aflatoxins levels of maize stored in traditional and improved clay granaries in rural conditions of Côte d’Ivoire.
Conclusion
This attempt suggests a better storage of maize cobs and grains treated with biopesticides over duration of six months. Beyond that period the sanitary quality of the maize is not acceptable because of a high risk of aflatoxins exposure. Hence, leaves of Lippia multiflora and Hyptis suaveolens could be potentially applied in food preservation, as alternatives to chemical pesticides in order to improve the self -life of staple foods, especially cereals.
The technology is inexpensive, easily carried and fits with the millennium guidelines of environment suitability. However, the study needs further investigation to preserve the quality, and ensure healthy and nutritional value of the maize after storage. Therefore, in view of the toxicity of aflatoxins, it is imperative to foster best practices of harvesting, drying an d storage of the maize grains in order to provide health safety to populations.
