Abstract
The production and utilization of groundnut ( Arachis hypogea L) has increased tremendously across all provinces of Mozambique in recent times. However, the presence of mycotoxins, especially aflatoxins has remained a critical food concern in both the human and livestock diet. In this study, the effect of harvesting time and drying methods on aflatoxin contamination were examined at two locations namely; Nampula Research Station (PAN) and Mapupulo Agricultural Research Center in Nampula and Cabo Delgado provinces respectively. A randomized complete block design in a split-split plot arrangement with four replications was used with three groundnut varieties; ( ICGV-SM-99568 , ICGV-SM-01514 and JL-24 ) as the main plot and three harvesting dates (10 days before physiological maturity, at physiological maturity and 10 days after physiological maturity) and two drying methods; (A-frame and tarpaulin) as the sub-plots. Groundnut samples were analyzed for aflatoxin contamination using immuno-chromatographic assay strips by the M-reader. In both locations, field observations indicated that on average aflatoxin contamination levels were lower at physiological maturity (H2) (≤ 10 ppb) compared to harvesting 10 days before (H1) ( ≤ 15 ppb) and 10 days after physiological maturity (H3) (≥ 20 ppb). It was also observed that the two drying methods were effective in prevention of aflatoxin contamination on groundnut kernels to levels lower than 20 ppb. However, aflatoxin contamination levels were significantly lower ( ≤ 12 ppb) as a result of the A-frame than the tarpaulin method. The results of this study therefore, have indicated that proper post-harvest management of groundnuts such as harvesting at physiological maturity and improved drying gave lowest aflatoxin contamination levels lower than the FDA/WHO regulatory levels of 20 ppb.
Highlights
Groundnut (Arachis hypogaea L.) is the third most important crop in Mozambique after maize (Zea mays) and cassava (Manihot esculenta) [1, 2]
The results showed that aflatoxin contamination of the nuts started at H1 and significantly increased with delayed harvesting time (H3)
This was attributed to higher than normal temperatures (≥30°C) and late season rainfall which created warm, moist conditions suitable for fungal growth, and subsequent higher aflatoxin contamination levels on the kernels. These outcomes are similar to earlier accounts that wetter and more humid conditions tend to aggravate aflatoxin levels as it enhances the growth of Aspergillus species and production of aflatoxins in groundnuts compared to drier climatic conditions [16]
Summary
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. 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. 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
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