1.1 Introduction
Maize (Zea mays) is an annual monoecious crop and the most important cereal in the world after wheat and rice with regard to cultivation areas and total production. Aflatoxins are naturally occurring mycotoxin that is largely produced by Aspergillus flavus and Aspergillus parasiticus species of fungi. This is a highly toxic secondary metabolite that contaminates a number of crops, causing a great economic loss (Cary et al., 2000; CAST, 2002). Several other moulds and fungi species also produce aflatoxin and these include A. nomius, A. pseudotamarii and A. bombycis (Peterson et al., 2001). The biosynthetic pathway of aflatoxin in A. flavus and A. parasiticus are similar and well characterized (Cary et al., 2000; Yu et al., 2004).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Aflatoxins are produced in certain foods and feeds, and undoubtedly the best known and most intensively researched mycotoxins in the world. It has been associated with various diseases, such as aflatoxicosis in livestock, domestic animals and humans throughout the world (Bhatnagar et al., 2003). Certain environmental factors influence the occurrence of aflatoxin; hence the extent of contamination will vary with geographic location, agricultural and agronomic practices, and the susceptibility of crop commodities to fungal invasion during pre-harvest, storage or processing periods (Bhatnagar et al., 2003).
Food security on the African continent has been worsening and deteriorating in recent decades. The proportion of the malnourished population has remained predominant in most Sub-Saharan African countries (FAO, 1996). To eradicate or mitigate this situation, an increase in productivity of agricultural food crops, especially groundnut, maize, rice millet and beans, are not only necessary as these crops form part of the staple foods and the main cash crops of most of these countries, but must go hand-in-hand with better farming practices and post-harvest handling.
These agricultural products are very prone to aflatoxin contamination, particularly during growth periods, harvesting, threshing and drying (Siriacha et al., 1989). Contamination can also occur when grains are poorly stored, which can cause pest infestation and poor conditions that lead to an accelerated growth rate of Aspergillus and other fungi species (WHO, 2006). Aflatoxin-producing species of Aspergillus are common and widespread in nature. Grains are particularly susceptible to infection by Aspergillus following prolonged exposure to a high-humid environment, or damage from stressful conditions (Udoh et al., 2000).
Mycotoxins affect the nutritional and economic value of staple foods and cash crops, especially in developing countries like Africa. Of the many mycotoxins, aflatoxin is of major concern, especially in countries where agricultural practices are not strictly controlled, and human and animal exposure to mycotoxins is very high (Wagacha et al., 2008). Attention is only paid to meet export criteria while the effects of aflatoxin on the health of the local consumers are not prioritized. The contamination of foods with aflatoxin has in recent times created a great alarm on food security in Africa (Leslie, 2005). It has caused massive economic losses on export and import markets, and diseases such as impaired immune system, cancer and stunted growth in infants (Williams et al., 2004).
In Nigeria, groundnut, maize and other cereals and legumes are sold in the open market with less or no regulation of quality. Most of the contaminated foods find their way into households and restaurants and patronized by unsuspecting consumers. The assessment of the levels of aflatoxin in food crops and identification of fungi responsible for their contamination will inform policymakers to improve upon proper handling of grains to reduce the toxin in foods. The main objective of this study was to evaluate the diversity of Aflatoxin-producing fungi and levels of Aflatoxin B1 in selected cereals and legumes from Lagos Central Market in Nigeria using HPLC, PCR and microbial culture techniques.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to determine the Aflatoxin B1 and Fungal Assessment to Stored Maize.
1.3 Statement of Problems
The year 2000 was set as a target date for the attainment of food self sufficiency by all African countries in the action plan agreed upon in Lagos, Nigeria (Salih, 1994). However, roughly 5 years after the deadline, little or nothing had been achieved. This failure is evident by the excess capacity in the agro industrial sector; rapid increase in food prices and the gradual resort to food importation among others. Rapid growth in agriculture is essential for broad based economic growth, but acceleration in agricultural growth requires sound use of science and technology embodied in improved seed, fertilizer, agrochemical and other agronomic practices. However without an efficient and cost effective supply of these inputs at the farm gate, science based growth in agricultural productivity cannot be achieved.
Furthermore, with the phased withdrawal of subsidies and privatisation, the input markets remained underdeveloped and fragmented and farmers do not receive good quality inputs and pay unreasonable high prices despite the fact that the private sector in Nigeria has a potential to supply agricultural inputs in a cost effective manner (IFDC, 2001). One of the problems cited as constraining the production of maize in Nigeria is stagnant production technology among Nigerian farming community, majority of who are small-scale producers. The reason for this could be attributed to resource productivity as studies have confirmed inefficiency in resource utilisation in both food and cash crops in Nigeria (Olagoke, 1999 and Olayide, 1979).
Furthermore, the extent to which inputs supply and productivity relates to a shortfall in food demand and supply in Nigeria is not clearly understood. At the same time, the impact of factors such as the policy environment, and the availability of markets for the disposal of farm outputs is not often considered despite the fact that such factors make farmers to work harder and thus, produce higher outputs.
1.4 Aim and Objectives of Study
The aim of the study is to determine the Aflatoxin B1 and Fungal Assessment to Stored Maize. In achieving this aim, the following specific objectives were laid out as follows:
- To evaluate the diversity of Aflatoxin-producing fungi and levels of Aflatoxin B1 in stored maize
- To evaluate the fungal load of dried stored maize samples from different markets
- To isolate and identify aflatoxin-producing Aspergillus species from dried stored maize samples.
1.5 Significance of Study
The following are the relevance of the Determination of Aflatoxin B1 and Fungal Assessment to Stored Maize research work;
- The study provides adequate information for increasing productivity in the livelihoods of smallholder farmers;
- The study provides information of how to make use maize in making diesel, and biofuel.
- This study will provide information relating to the input prices and output relationship in maize production.
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The study focuses on the Determination of Aflatoxin B1 and Fungal Assessment to Stored Maize.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.8 Definition of Terms
Maize: Maize is another word for corn, the tall-growing grain that produces yellow kernels on long ears.
Prospect: A prospect is the possibility that something fabulous will happen.
Problem: Problem is a matter or situation regarded as unwelcome or harmful and needing to be dealt with and overcome.
