RESUME Les aflatoxines sont des toxines produites principalement par les moisissures du genre Aspergillus (Aspergillus flavus et Aspergillus parasiticus).Les molécules les plus abondantes de la famille des aflatoxines sont l'AFB1, l'AFB2, l'AFG1 et l'AFG2. C'est dans les pays africains, d'Asie du Sud et d'Amérique du Sud, où le climat est chaud et humide, que la contamination des céréales par l'aflatoxine est plus fréquente. Dans la plus part des pays africains, près de la moitié de la production céréalière a une teneur en aflatoxine supérieure aux standards internationaux. L'estimation de la quantité d'aflatoxine dans le maïs en 2016 a donné des intervalles de [1,06-852,2ppm] au Sénégal, de [8,0-1081ppm] en Tanzanie, avec un taux d'échantillons dépassant la limite maximale qui varie entre 2-85% de 622 échantillons. Au niveau africain la contamination des céréales par cette toxine a des conséquences économiques, alimentaires et surtout sanitaires. Pour lutter contre la présence de l'aflatoxine dans des céréales en Afrique des méthodes chimiques, physiques et biologiques sont employées, bien qu'elles soient limitées. © 2016 International Formulae Group. All rights reserved.Mot clés : Aflatoxine, Contamination, Céréale, Lutte, Prévalence, Afrique. African crops contamination by aflatoxin: review of existing methods of control ABSTRACTAflatoxins are toxins produced mainly by Aspergillus (Aspergillus flavus and Aspergillus parasiticus). The most abundant molecules of aflatoxins family are AFB1, AFB2, AFG1 and AFG2. It is in African countries, South Asia and South America, where the climate is hot and humid, that contamination of crops with aflatoxin is more common. In most African countries, nearly half of crops production has higher aflatoxin content compared to international standards. The estimate of the quantity of aflatoxin in crops on the year 2016 E. DIEME et al. / Int. J. Biol. Chem. Sci. 10(5): 2285-2299, 2016 2286 has yielded intervals [1. 06-852.2ppb] in Senegal, [8.0-1081ppb] in Tanzania, with a sample rate exceeding the maximum limit that varies between 2-85% of 622 samples. The level of grain aflatoxin contamination in Africa has economic and food consequences; and especially impact the human health. To fight against the contamination of Africa crops by aflatoxin, physical, chemical and biological methods are employed with obvious limits.

Instant compound flours were developed from local Senegalese plants, using a single-screw extruder (Technochem brand) previously designed for soybean processing. Adapting the parameters of the equipment to our local cereals (sorghum, millet, and maize), legumes and oleaginous plants was the first technical step performed. We modified the parameters of the extruder and then carried out several tests to determine the best blend obtained from several combinations of co-extruded raw materials that led to compound flour (70% millet, 15% peanut, and 15% cowpea) of high nutritional value. Prior to this step, analyses were run on each compound of the blend to determine their selected macro (moisture, ash, acidity, protein and lipid) and micro composition (iron, magnesium, and zinc). For a good result, the extruder parameters were set at a frequency of 48.2 Hz and a temperature of 280°F. Three shear rings of 1.47 mm of diameter each, followed by a bigger one (1.59 mm), were respectively inserted along the end of the screw; the rotational speed of the screw was set at 900 rpm and total liquid content was 30%. The final instant flour obtained was composed of 13.99% protein, 9.37% fat, 4.10% moisture, 1.64% ash and 0.08% acidity. The flour was split in four different batches and each was flavored with one of four powders (mango, papaya, baobab fruit or carrot). On a hedonic scale from 1 to 9, the results of the organoleptic tests performed by 21 trained panelists showed that all four samples received a score higher than 5 in all three categories (taste, color, and texture). However, taste wise papaya flavor received a better score followed by mango, carrot and baobab fruit flour. In conclusion, changing the parameters of the extruder helped obtain a well-accepted instant blend from local plants when local fruits were used to enhance flavors.

La non maîtrise ou l’ignorance des bonnes pratiques de stockage ou de conservation conduit souvent à des pertes des récoltes en Afrique. Ces dernières peuvent entrainer l’insécurité alimentaire qui est toujours une réalité en Afrique. Ceci illustre que les pratiques culturales et surtout la conservation post-récolte des céréales principaux aliments de base des populations, demeurent un problème majeur en Afrique. Une enquête a été réalisée au Sénégal dans les régions de Tambacounda et de Thiès pour étudier les pratiques culturales des producteurs de sorgho et caractériser la gestion post-récolte dans les zones de production. L’étude a été réalisée auprès de 384 producteurs de sorgho issus de 44 villages. Les zones ont été choisies suivant leur niveau de production et de pluviométrie. La taille de l’échantillon a été déterminée en utilisant l’approximation normale de la loi binomiale. Les résultats ont montré que dans chacune des régions, la proportion d’agriculteur masculin est de 97% et les ethnies dominantes sont les sérères (86%) à Thiès, les peuls et les wolofs (47% et 21%) à Tambacounda. Les semences provenaient principalement de la récolte précédente (10 à 76%) des cas et des distributeurs d’intrants agricoles (2 à 65%). Ces taux diffèrent suivant la région. Les variétés certifiées sont cultivées par 70% des producteurs à Thiès. Les variétés traditionnelles sont utilisées par 98% de ceux de Tambacounda. Cette étude a aussi révélé que les paysans utilisent différents types de séchage à la maison ou aux champs. Parmi eux 79% stockent leur récolte dans des cases, 14% dans des magasins communautaires ,7% dans des greniers sous forme de panicules ou de grains représentant respectivement 22 et 75%. Ces méthodes de prise en charge post-récolte du sorgho diffèrent selon la zone et sont dans certains cas inadéquates. Elles peuvent favoriser la déperdition post-récolte du sorgho et sa contamination par les moisissures, d’où l’intérêt de bien former les acteurs de cette filière.Mots clés : Culture, stockage, céréale, enquête, variété.   English Title: Cultural practices and post-harvest management of sorghum in Senegal Failure to master or ignore good storage or conservation practices often leads to crop loss or spoilage of food in Africa. These can lead to food insecurity and threaten food safety. As a result, cultivation practices and especially the post-harvest conservation of cereals, the main staple food of the populations, remain a major problem in West Africa. A survey was carried out in Senegal in the regions of Tambacounda and Thies to study the cultural practices of sorghum producers and characterize post-harvest management in the production areas. The study was carried out with 384 sorghum producers from 44 villages. The zones were chosen according to their level of production and rainfall. The sample size was determined using the normal binomial approximation. The results showed that in each of the regions, the proportion of male farmers is 97%, and the dominant ethnic groups are the Serer (86%) in Thies, the Peul and the Wolof (47% and 21%) in Tambacounda. The seeds came mainly from the previous harvest (10 to 76%) of the cases, and from agricultural input distributors (2 to 65%). These rates differ by region. The certified varieties are cultivated by 70% of the producers in Thies. The traditional varieties are used by 98% of those of Tambacounda. This study also revealed that farmers use different types of drying at home or in the fields. Among them, 79% store their harvest in huts, 14% in community stores, 7% in granaries in the form of panicles or grains, representing 22 and 75% respectively. These post-harvest management methods for sorghum differ by area and are in some cases inadequate. They can encourage the post-harvest loss of sorghum and its contamination by molds, hence the importance of properly training the players in this sector.Keywords: Crop, storage, cereal, survey, variety.

Contrasting with the favorable climatic and environmental conditions, improper post-harvest management of cereals is often responsible for high levels contamination of aflatoxin in Africa. This study aimed at identifying critical periods of aflatoxin concentrations in cereals. Thus, a survey followed by sampling at each stage of production for aflatoxin quantification using the AFLA-V AQUA test procedure (0-100 ppb) was carried out at different farmer sites in Velingara. The survey revealed that only 9.36% of farmers were aware of molds and aflatoxin. Quantification of aflatoxin revealed that only 4.9% of farmers had contaminated crops in the first stage of harvest (ears drying). However, during traditional storage, the contamination rate increased up to 39%, proportional to the aflatoxin level that reaches 70 ppb. Two stages of the post-harvest management were particularly critical in the accumulation of aflatoxin in cereals: drying, especially the bare cobs and storage.

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