**1. Introduction**

Groundnut (*Arachis hypogaea* L.) is the third most important crop in Mozambique after maize (*Zea mays*) and cassava (*Manihot esculenta*) [1, 2]. It is a major cash crop and the main source of

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

cooking oil for many Mozambican families [1, 3]. In terms of production, groundnut occupies the largest area among the grain legumes in the country [1, 4] with the largest concentration in Nampula, Zambezia, and Cabo Delgado provinces.

By assessing different harvesting times and different drying methods, it was hoped that the results would enhance the use of good postharvest handling practices (drying and harvesting

Effect of Harvesting Time and Drying Methods on Aflatoxin Contamination in Groundnut in Mozambique

http://dx.doi.org/10.5772/intechopen.77300

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The study was conducted during the 2015/2016 growing season in two locations, namely Nampula Research Station (PAN) and Mapupulo Agricultural Research Center (CIAM), located in Nampula and Cabo Delgado Provinces, respectively. Nampula Research Station (PAN) is located about 7 km east of Nampula city in Northern Mozambique (15° 09′ S, 39° 30′ E) and is elevated at 432 m above sea level. The soil type is sandy loam, and the vegetation is predominantly grassland. The average rainfall is slightly over 1000 mm which starts around November/December up to April/May, with its peak in January. The maximum temperature in the region is about 39°C and the minimum temperature is 19°C [1]. Mapupulo Agricultural Research Center (CIAM) is located about 18 km south of Montepuez town about 200 km west of Pemba the capital of the province, which lies at (13° 12′ S, 38° 53′ E) and is elevated at 476.7 m above sea level. The soils are clay loam and deep brown loam. It receives annual precipitation of 1200 mm on average from November/

The study was carried out during the 2015/2016 growing season at PAN and CIAM. The test materials were evaluated using a randomized complete block design in a split-split plot arrangement with four replications. The main plot was the variety, while harvesting time and drying method were subplots. The net plots were six rows by 6-m long with one seed per planting station which were spaced at 50 cm apart, and the planting stations were spaced at 10 cm. Spanish groundnut varieties (take 90 days to mature) were used for the study, namely *ICGV-SM-99568*, *JL-24*, and *ICGV-SM-01514*. The experiments were established on 23rd and 24th December at CIAM and PAN, respectively, at the onset of the rains. No fertilizer, pesticides, or supplemen-

The assessment of the effect of harvesting time and drying method on aflatoxin contamination among the varieties involved dividing the net plots into three harvesting time treatments: (i) 10 days before physiological maturity indicated as H1; (ii) at physiological maturity indicated as H2, and (iii) 10days after physiological maturity indicated as H3. The following drying treatments were imposed on the plants from each of the plots: (1) pulling and inverted windrowing of plants for 3 days, followed by further drying of the plants with the pods on constructed "A-Frames" for 4 weeks and (2) pulling and inverted windrowing of plants for 3 days, followed by stripping of the pods and further drying on interlaced tarpaulins mats for 4 weeks. The samples were later

December to April/May, and the average temperature is between 20 and 25°C [1].

tary water were applied, and no seed treatment before planting was applied.

subjected to aflatoxin testing using the immune-chromatographic method mreader.

time) that would minimize aflatoxin contamination of groundnuts at the farmer level.

**2. Materials and methods**

**2.1. Description of the study area**

**2.2. Field establishment**

Despite its importance as food, the presence of mycotoxins, especially aflatoxins, has the potential to limit its use in both the human and livestock diet [5]. Furthermore, aflatoxin contamination of agricultural crops, such as groundnut and cereals, causes annual losses of more than US \$750 million in Africa and more than US \$100 million per year in USA [6]. Poor management practices by farmers and adverse climatic conditions at harvest and postharvest are some of the prompting factors for postharvest aflatoxin contamination. The timing of harvesting greatly influences mold production at harvest [7]. In [8], it is highlighted that farmers tend to delay in harvesting their crops which results in over maturity leading to mold infections and subsequent aflatoxin contamination.

Correct and proper drying of harvested groundnuts is very essential in prevention of fungal infection of the crop. Additionally, proper drying is critical for maintaining seed quality for consumption and safe storage. However, the traditional groundnut drying techniques in Mozambique involve field and bare ground drying, which rather promote fungal growth and consequent aflatoxin contamination [9]. Moreover, these are slow, time-consuming, and labor-intensive, involving lots of crop handling, and due to rains that normally persist at harvesting and drying times, it is difficult to achieve the recommended moisture content for safe storage (which is 6–8%). In addition, the crop is persistently exposed to the soil, which is a major source of contamination by fungi [10, 11].

Ideally, pods should be dried with sufficient air circulation and in the shade [10]. This is because excessive exposure to the sun can affect the quality of the seed. Two principal methods are used elsewhere in Africa, both of which can produce good quality seed with reduced levels of fungal infection [12]. These drying methods are namely Corks and A-Frame methods. However, the traditional drying techniques in Mozambique involve bare ground drying and are a major source of fungal contamination. Furthermore, some farmers do not dry groundnuts immediately after harvest, due to labor constraints needed for plucking [9]. Thus, they heap the nuts either in the field or in houses. These practices, coupled with inefficient and slow drying process under the humid conditions, enhance aflatoxin contamination greatly.

Although research on the effect of harvesting time and drying method of groundnut on aflatoxin development has received increasing consideration worldwide, in Mozambique, research on this matter is still very scarce [13]. However, there is evidence to suggest that aflatoxin contamination is a major food-safety concern in Mozambique where the environmental conditions and socio-economic problems are conducive due to poor postharvest and storage management and subsequent food spoilage and aflatoxin contamination. This is evident by the levels of certain types of cancer and the negative correlations between aflatoxin in the diet and development in children and the declining of groundnut exports from Mozambique since 1998 [13, 14].

By assessing different harvesting times and different drying methods, it was hoped that the results would enhance the use of good postharvest handling practices (drying and harvesting time) that would minimize aflatoxin contamination of groundnuts at the farmer level.
