Fungal contaminants in major food staples in Kenya have negatively impacted food security. The study sought to investigate peanut market characteristics and their association with levels of aflatoxin in peanuts from Western, Nyanza and Nairobi Provinces of Kenya. Data were collected from 1263 vendors in various market outlets using a structured questionnaire, and peanuts and peanut products from each vendor were sampled and analyzed for aflatoxin levels. Thirty seven per cent of the samples exceeded the 10 mg/kg regulatory limit for aflatoxin levels set by the Kenya Bureau of Standards (KEBS). Raw podded peanuts had the lowest (c 2 ¼ 167.78; P < 0.001) levels of aflatoxin, with 96% having levels of less than 4 mg/kg and only 4% having more than 10 mg/kg. The most aflatoxin-contaminated products were peanut butter and spoilt peanuts, with 69% and 75% respectively, exceeding 10 mg/kg. A large proportion of peanuts in the country (44%) were traded through informal open air markets; 71.8% of products from supermarkets were safe according to KEBS and the EU regulatory limits, while only 52% from informal markets met this threshold (c 2 ¼ 95.13; P < 0.001). Packaging material significantly (c 2 ¼ 73.89; P < 0.001) influenced the amount of aflatoxin in the product, with the majority (68%) of peanut samples that were stored in plastic jars having >10 mg/kg of aflatoxin. Over 70% of all storage structures were poorly ventilated and dusty. Sorting comprised 53% of the various crop protection measures used by traders post-harvest. To reduce aflatoxin exposure to consumers, set standards need to be complemented by strict monitoring systems and education of producers, processors and consumers in crop commodities other than maize, which has received the most attention in Kenya. Alternative uses of contaminated produce need to be explored.
A survey was conducted in Nairobi, Nyanza and Western provinces in Kenya between March and July 2009 with 1263 peanut products sampled out of which 705 samples underwent microbial analysis. The study aimed at determining the incidence of fungal species e emphasis on Aspergillus section Flavi e associated with peanut products. A 0.5 kg representative sample was obtained from each surveyed vendor and the colony forming units (CFU) of fungal species determined. The samples were also analyzed for total aflatoxin level while isolates of Aspergillus flavus and Aspergillus parasiticus were screened for production of aflatoxin B1, B2, G1 and G2. Eight fungal species were detected in the samples and were in decreasing order of CFU/g of sample: A. flavus S-strain (467), A. flavus L-strain (341), Penicillium spp. (326), Aspergillus niger (156), Aspergillus tamari (27), Aspergillus alliaceus (21), A. parasiticus (10), and Aspergillus caelatus (5). The overall incidence of A. flavus S-strain in samples from Nairobi was 92 and 1425% higher than samples from Nyanza and Western regions, respectively. The combined incidence of A. flavus and A. parasiticus was varied significantly (p 0.05) with peanut product: peanut flour (69%), shelled raw peanuts (53%), spoilt peanuts (49%), boiled podded peanuts (45%), podded peanuts (39%), peanut butter (31%), fried peanuts (22%) and roasted peanuts (20%). Seventy three percent of A. flavus and A. parasiticus isolates produced at least one of the aflatoxin types, with 66% producing aflatoxin B1. The total aflatoxin level among peanut products ranged from 0 to 1629 mg/g; and there was a positive correlation (r ¼ 0.2711) between the incidence of A. flavus and A. parasiticus, and total aflatoxin level. The high incidence of aflatoxin producing fungi in peanuts traded in Kenyan markets implies a risk of aflatoxin contamination, highlighting the need for stakeholders to promote sound practices at all stages of the peanut value chain in order to minimize market access by non-complying products.
Peanut kernels of Homabay Local, Valencia Red, ICGV-SM 12991 and ICGV-SM 99568 cultivars were stored for six months in jute, polypropylene and polyethylene bags to assess the effect of storage bags, temperature and R.H. on fungal population and aflatoxin contamination. Moisture content (M.C.), fungal population and aflatoxin levels were determined before storage and after every 30 days during storage. Isolates of Aspergillus flavus and A. parasiticus were assayed for production of aflatoxin B1, B2, G1 and G2. The correlation between MC, population of A. flavus and A. parasiticus and aflatoxin levels in peanuts was also determined. Six fungal pathogens were commonly isolated from the peanut samples and occurred as follows in decreasing order: Penicillium spp. (106.6 CFU/g), A. flavus L-strain (4.8 CFU/g), A. flavus S-strain (2.9 CFU/g), A. niger (2.6 CFU/g), A. parasiticus (1.7 CFU/g) and A. tamarii (0.2 CFU/g). The overall population of A. flavus L-strain was 66% higher than that of A. flavus S-strain. Ninety one percent of A. flavus and A. parasiticus isolates produced at least one of the four aflatoxin types assayed, with 36% producing aflatoxin B1. Total aflatoxin levels ranged from 0 -47.8 µg/kg with samples stored in polyethylene and jute bags being the most and least contaminated, respectively. Eighty nine percent and 97% of the peanut samples met the EU (≤ 4 µg/kg) and Kenyan (≤ 10 µg/kg) regulatory standards for total aflatoxin, respectively. Peanuts should be adequately dried to safe moisture level and immediately packaged in a container -preferably jute bags -which will not promote critical increases in fungal population and aflatoxin contamination.
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