MYCOFLORA AND AFLATOXIN LEVELS IN WALNUT SAMPLES STORED IN DIFFERENT PACKAGING MATERIALS IN OGUN STATE

Aflatoxin levels in nuts and fruits pose a great threat to food storage and availability. This study aimed at determining the mycoflora and aflatoxin level in stored walnut under various conditions. Freshly harvested walnuts were stored for 90 days in three different media: jute bags, Plastic containers and sterile polythene bags under room (37ᵒC) and refrigeration (4ᵒC) temperature. After 90 days of storage, the stored walnuts were examined for fungal growth at one month interval after which colonial and morphological characterization were carried out to identify the fungi present. Proximate analysis and aflatoxin content of the walnut samples were determined by standard methods. Fungi isolated from the walnuts include; Aspergillus niger, Saccharomyces cerevisae, Penicillum notatum, Aspergillus sydowi, Fusarium oxysporium, and Rhizopus stolonifer. Walnuts stored in plastic container at room temperature had the lowest aflatoxin level of 0.002 ng/kg while that stored in polythene bags had the highest (0.054 ng/kg). Proximate analysis also revealed that walnuts stored in polythene bag reduced significantly (p<0.05) in protein, ash content, fat, fibre, moisture and carbohydrates while samples stored in jute bag and plastic container remained unchanged. This study shows that storage methods contributed to the overall quality, shelf life and aflatoxin content of walnut and hence care should be taken during post harvesting process.

Physiological Effects of Green-Colored Food-Derived Bioactive Compounds on Cancer

Green-colored foods, such as broccoli, sprouts, soybean, and green leafy vegetables are considered one of the representative healthy foods for containing various functional ingredients that can combat chronic diseases, including diabetes, obesity, and cancer. Herein, we reviewed the anti-cancer activities and the underlying mechanisms of some important bioactive compounds, such as sulforaphane, catechins, chlorophyll, isoflavone, indole dervatives, and lutein, present in green-colored foods. In vivo and clinical studies suggest that sulforaphane, a sulfur-containing compound found in cruciferous vegetables, can ameliorate prostate and breast cancer symptoms by arresting cell-cycle progression and modulating Ki67 and HDAC expression. A green tea compound, known as epigallocatechin-3-gallate (EGCG), has shown remarkable anti-cancer effects against prostate cancer and lung adenocarcinoma in human trials through its antioxidative defense and immunomodulatory functions. Chlorophyll, a natural pigment found in all green plants, can regulate multiple cancer-related genes, including cyclin D1, CYP1A, CYP1B1, and p53. Epidemiological studies indicate that chlorophyll can substantially reduce aflatoxin level and can mitigate colon cancer in human subjects. Remarkably, the consumption of soy isoflavone has been found to be associated with the lower incidence and mortality of breast and prostate cancers in East Asia and in Canada. In vivo and in vitro data point out that isoflavone has modulatory effects on estrogen and androgen signaling pathways and the expression of MAPK, NfκB, Bcl-2, and PI3K/AKT in different cancer models. Other green food bioactive compounds, such as indole derivatives and lutein, also exhibited suppressing effects in rodent models of lung, liver, stomach, cervical, and prostate cancers. In addition, some micronutrients, such as folate, riboflavin, retinoic acid, and vitamin D3 present in green foods, also showed potential cancer suppressing effects. Taken together, these data suggest potential chemopreventive functions of the bioactive compounds from green-colored foods. This paper could be beneficial for further research on the anti-carcinogenic effects of green-colored food-derived compounds, in order to develop green chemotherapeutics for cancers.

Aflatoxin contamination in Tanzania: quantifying the problem in maize and groundnuts from rural households

Aflatoxins are toxic and carcinogenic secondary metabolites, produced by Aspergillus flavus and Aspergillus parasiticus, which contaminate food and feed and threaten human and animal health. To assess the prevalence of aflatoxins in Tanzania, 180 groundnut and 200 maize samples were collected from 9 and 10 districts, respectively. Aflatoxin contamination was quantified using high performance liquid chromatography. Aflatoxins were detected in samples collected from all districts and prevalence ranged from 92 to 100% for groundnuts and 10 to 80% for maize. The mean aflatoxin level for groundnuts was 6.37 μg/kg and the highly contaminated sample had 40.31 μg/kg. For maize, the mean aflatoxin level was 12.47 μg/kg and the highly contaminated sample had 162.40 μg/kg. The estimated average probable daily intake (APDI) of aflatoxin B1 (AFB1) from groundnuts consumption was 1.88 ng/kg body weight/day, while for maize, it ranged between 151.98-272.89 ng/kg body weight/day. The APDI for both groundnut and maize exceeded the provisional maximum tolerable daily intake (PMTDI) of AFB1 for adults (1 ng/kg body weight/day), bringing about health concerns for populations in Tanzania. Another alarming finding was that 75% of the farmers who provided samples for analysis were not aware of aflatoxins or the negative health impacts from consuming contaminated products. Results reported in this paper show that aflatoxin contaminated staple crops are widely distributed in Tanzania and that the risk of human exposure is high due to diet preferences. Awareness campaigns are required to inform and protect farmers and consumers.

Efficacy of different hermetic bag storage technologies against insect pests and aflatoxin incidence in stored maize grain

The performance of six grain storage technologies for the control of insect pests in maize was evaluated over a 36-week (9-month) storage period. The six technologies used were: two ZeroFly® hermetic bag brands (laminated and non-laminated); Purdue Improved Crop Storage (PICS) bag; non-hermetic ZeroFly® bag; woven polypropylene (PP) bag containing maize grain treated with Actellic Gold® Dust (pirimiphos-methyl 1.6% + thiamethoxam 0.3%) and woven PP bag containing untreated grain. Each bag was filled with 50 kg maize grain and four replicates of each were set up. With the exception of the non-hermetic ZeroFly® bag, 50 live adults of the larger grain borer Prostephanus truncatus and of the maize weevil Sitophilus zeamais, were introduced into all the bags. Insects were not introduced into the non-hermetic ZeroFly® bag to assess its effectiveness in repelling infestation from outside. Parameters recorded were gas composition (oxygen and carbon dioxide) levels inside the bags; weight of flour generated by insect feeding activities; grain moisture level; live adult insect counts; grain damage and weight loss; grain germination rate and aflatoxin level. At termination, the plastic liners of the hermetic bags were examined for perforations. Results show that oxygen depletion and carbon dioxide evolution were faster in ZeroFly® hermetic compared to PICS bags. Throughout the 36-week storage trial, grain damage remained below 4% and weight loss below 3% in all the treatments except in the untreated PP bags in which it increased to 81.1 and 25.5%, respectively. The hermetic PICS, ZeroFly® and Actellic Gold dust-treated PP bags maintained grain germination at 60%, which was lower than the initial 90%, while in untreated control, it reduced to 4.7%. The mean aflatoxin levels fluctuated between 0.39 and 3.56 parts per billion (ppb) during 24 weeks of storage in all the technologies tested, which is below the acceptable maximum level of 10 ppb in maize. Based on the evaluation results, it can be concluded that hermetic PICS and ZeroFly® bags and woven PP bag with Actellic Gold dust-treated grain effectively protected stored maize grain from insect attack and weight losses. Appropriate strategies and mechanisms for the effective and efficient adoption of hermetic storage bag technology at scale would contribute towards global food security.

Aspergillus species and aflatoxin contamination in pepper (Capsicum annuum L.) in West Gojjam, Ethiopia

Pepper (Capsicum annuum L.) is an important spice and source of income for smallholder producers in Ethiopia. Since the larger proportion is for the market, it takes a significant share of the national income from export commodity. However, often the product was rejected by some of the European Union markets due to the maximum aflatoxin level accumulations beyond their acceptable limits. So, the present study was carried out to highlight the importance of Aspergillus species invasion in pepper, and levels of aflatoxin contamination at maturity in the field (pod form), farmers' storage and local market (powder form)in West Gojjam, Ethiopia. A total of 135 pepper samples were collected from three districts of West Gojjam(Burie, Jabitehnan, and Fnoteselam), Ethiopia for fungal and aflatoxin analysis.The producers used a pre-validated structured questionnaire to obtain information on pepper production practices. Aspergillus species isolates were recovered using potato dextrose agar (PDA) medium and counting was through dilution method (cfu g-1). The pepper pods were ground to a fine powder for aflatoxin analysis using Enzyme-Linked Immunosorbent Assay(ELISA). The prevalence of infected samples revealed that, pre-harvest samples(51%) were less infected by Aspergillus species, compared to local markets (65 %) and storage (79 %).Aspergillus flavus species were recovered in pre-harvest samples, whilst A.niger were found in local market samples. Aflatoxin contamination at pre-harvest, storage, and local market were 10, 47, and 42 % with levels which ranged from non-detected to 10.6, 0.3 -17.1 and 3.1 -19.2 ppb, respectively.The mean aflatoxin concentration detected from storage samples (10.6 ppb)and local market (12.6 ppb)were found to be above the tolerable limits set byEU (5 ppb) in pepper products.From the findings in this study, proper drying, physical separation of molded pods and use of clean storage structures should be implemented along the production chain in order to reduce aflatoxin contamination in pepper in Ethiopia.

Awareness, handling and storage factors associated with aflatoxin contamination in spices marketed in Dar es Salaam, Tanzania

A structured questionnaire was used to collect information of awareness, knowledge and practices associated with aflatoxin contamination in spices from 30 retailers in Dar es Salaam. Aflatoxin contamination in spices was analysed using high performance liquid chromatography (HPLC) with fluorescence detection using post column derivatization. Data were statistically analysed to assess factors associated with aflatoxin contamination in the study community. 58% of the spice samples were contaminated and the mean of total aflatoxin level in ginger, cinnamon, cloves and cardamom was 2.67, 2.88, 2.79 and 2.26 μg/kg, respectively. Significant majorities (96.7%) of the respondents were not aware of aflatoxin contamination of spices during storage and its effect on health. Farmers as source where spices were procured and storage time of more than 14 days showed significant association with aflatoxin contamination with odds ratio (OR) = 0.178, 95% confidence interval (CI) = 0.061-0.525, P=0.002 and OR=3.608, 95% CI=1.099-11.845, P=0.034, respectively. This is the first report of aflatoxin contamination in spices consumed in Tanzania. The levels of contamination are high and associated spices that was procured from farmers and long storage time. This calls for urgent raising of awareness and knowledge on good management practices for prevention of aflatoxin contamination of spices in Tanzania.

Drying Performance and Aflatoxin Content of Paddy Rice Applying an Inflatable Solar Dryer in Burkina Faso

The drying performance of paddy rice using an inflatable solar dryer (ISD), or also known as GrainPro® Solar Bubble Dryer™, was evaluated and compared to conventional sun drying in Burkina Faso. Drying time was around eight hours. Thermal imaging was conducted to observe temperature distribution in the ISD during drying and mixing. Shadow casting was observed in the ISD due to the round shape of the black plastic film, which reduced the temperature of the paddy rice to about 10 °C. The temperature inside the ISD was up to 13 °C higher than the ambient temperature, whereas the temperature of paddy rice on the top layer was about 5 °C higher than on the bottom. The final moisture content of paddy rice dried in the ISD and under the sun was not considerably different. Under certain circumstances, impurities in paddy rice dried in the ISD could be substantially lower than for sun drying. The aflatoxin level of paddy rice was under the maximum limit of the EU regulation. Drying paddy rice seemed to be effective to remove aflatoxin type AFG2 content. Further adaptation of the ISD design for drying operations on rough surfaces and sandy soils is suggested.