>Magister Scientiae - MSc / Subsistence farmers may contribute significantly to food production, food
security, and employment in South Africa. However poor storage practices and
contamination with mycotoxins, particularly fumonisins and aflatoxins impacts
adversely on production, food safety and food security. Mycotoxins are toxic
natural food-borne compounds which frequently contaminate agricultural produce
worldwide. They are hazardous to humans and animals and result in significant
production losses for farmers. This study focused on former Bantustans in Northern South Africa, namely Vhembe District Municipality (Limpopo) and Gert Sibande District Municipality (Mpumalanga). The aim was to assess mycological and mycotoxin contamination of crops grown by subsistence farmers. A semi-structured questionnaire was administered to randomly thirty-nine households. Data on demographics, storage
practices and production during period of 2011 and 2012 cropping seasons were
collected. One hundred and fifteen (115) crop samples (maize, beans and peanuts)
were collected for analysis. Standard mycological methods and validated mycotoxin analysis methods (HPLC and LC- MS/MS) were used. It was found that maize was the staple food in both provinces, with a significant difference (p = 0.0184) in its production between the two districts; Vhembe produced 0.6 tonnes compared to 2.4 tonnes in Gert Sibande. The majority of the farmers for storage used traditional open wooden cribs (15/20) and steel tanks (5/20) while VDM farmers used sealed store houses 5/19 and 15/19 used polystyrene sacks. Aflatoxin occurrence was low with <1% of GSDM samples
contaminated compared to 11% of VDM samples. No significant difference (p >
0.05) was observed in the aflatoxin contamination in VDM samples between the
year 2011 and 2012. Samples from VDM households had higher Aspergillus
fungal infection (maximum incidence 69%) compared to GSDM (27%) over both
seasons. The most frequently isolated Fusarium species in VDM samples was F.
verticillioides (92%; 93%), and F. subglutinans (97%; 80%) in GSDM samples over seasons 2011 and 2012, respectively. Highest levels of fumonisins (FB1+ FB2) ranged between 1010 μg/kg and 12168 μg/kg with less than 30% extremely contaminated above the regulated limit in 91% of samples from Limpopo over both seasons (2011 and 2012). Fumonisin levels between the two seasons in VDM showed no significant difference (p>0.05). Only three (less than 5%) from 68% GSDM contaminated maize samples were above the FB1 and FB2 limit. In 2011, there were two highly contaminated maize samples (1762 μg/kg and 4598 μg/kg) with the other samples less than 600 μg/kg, whereas in season two (2012) all samples were below 200 μg/kg, except one highly contaminated sample (26115 μg/kg). None of the beans and peanuts
from Mpumalanga was contaminated with mycotoxins above the recommended limit, but from Limpopo 1/5 peanuts was found contaminated with aflatoxin G1 (41 μg/kg).
Natural occurrence and contamination of both fumonisin and aflatoxin in stored
home-grown maize from VDM was significantly (p < 0.0001) higher than GSDM
over both seasons. In general, Limpopo farmers’ experience lower harvests and
greater mycotoxin contamination of agricultural produce. This may be attributed
in part to poor storage practices and environmental and climatic conditions in that
agro-ecological zone.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uwc/oai:etd.uwc.ac.za:11394/3456 |
| Date | January 2013 |
| Creators | Mngqawa, Pamella |
| Contributors | Green, Ivan R., Shephard, Gordon, Katerere, David |
| Publisher | University of Western Cape |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Western Cape |
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