Aflatoxin prevalence data collection

Sampling framework & methodology

Introduction

Information is fragmented on the prevalence of aflatoxins, a variety of mycotoxin, in the maize value chain in Kenya and in the groundnut value chain in Mali. The purpose of this study is to generate a consistent database of aflatoxin prevalence along the maize and groundnut value chains through systematic sampling, and to identify critical points where intervention strategies are likely to have the greatest impact.

It is important to remember that aflatoxin-contaminated units are not homogeneously distributed throughout a plot: A few units are likely to be highly contaminated (mycotoxin clusters), while most of the grains are mycotoxin-free. Collecting samples only from the highly contaminated grains or from the mycotoxin-free ones will provide inaccurate final results. Therefore, proper sampling is one of the most crucial elements of addressing and managing aflatoxin contamination of food.

The overall objective of good sampling is to provide reliable samples for analysis that can represent the basis for ‘‘fit for purpose’’ investigations. Samples should be randomly gathered from many incremental samples, whether from the field or from grain/groundnut in bulk, in order for the analysis to be representative of the whole lot.

Meaningful sampling involves two key steps:

  1. Primary sampling: the process of ‘‘statistically’’ locating the sites (populations) from which samples should be taken (that is, making the decision of ‘‘why, where, and when’’ to collect the samples)
  2. Secondary sampling: the process of establishing how samples should be collected in order to be representative of the lot under investigation

A good sampling plan should cover the full range of environmental variables, including multiple elevations and diverse weather conditions.

Author: 
Mahuku, George
Nzioki, Henry Sila
Waliyar, Farid
Diarra, Bamory
Kodio, Ondie
Published date: 
2010
Publisher: 
International Food Policy Research Institute (IFPRI)
Series number: 
1
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