8 research outputs found
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Losses in sweet potato quality at harvest and during the post-harvest handling in the Mwanza Region of Tanzania
A preliminary survey of the sweet potato marketing chain, from the farm to the market, indicated that substantial loses in quality can occur at all stages. Sacks, containing between 107 and 114 kg of sweet potatoes took between 16 and 23 hours to reach the market. After leaving the farm, they were transported by bicycle, trolley, canoe, ship and light commercial vehicle. Assessment of the sweet potatoes, immediately after harvesting, indicated that approximately 20% to 35% of the sweet potatoes had minor cuts, 14% to 28% had breaks, 19% to 60% had signs of minor skinning, 13% to 59% had skin weevil and 1% to 4% burrowing weevil damage. After transport from the farm to the market, the level of damage in freshly harvested sweet potatoes increased such that 100% of the sweet potatoes had skinning damage, most severely, and 38% to 56% had breaks. Transport had little impact on the proportion of sweet potatoes with cuts or weevil damage. Shrivelled sweet potatoes were less susceptible to damage. The presence of rots, however, led to the sweet potatoes receiving a nominal market value. Handling of the sacks was monitored by visual observations and by shock, temperature and humidity measurements recorded by an 'electronic sweet potato', designed and assembled at NRI, which was inserted into the centre of the sacks. The most severe handling (shocks above 20g) occurred during loading and unloading from the ship, at the customs station of the port and at the markets and appeared to be associated with the occurrence of major breaks. The temperature (220C to 340C) in the sacks was optimum for curing although the very high humidity (greater than 95%) might lead to the occurrence of rots. Further studies will investigate seasonal variations along with other methods of transport to suggest practical and economic recommendations on improved transport and handling practices and direct future research
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HPLC method for the analysis of organic acids, sugars, and alcohol in extracts of fermenting cocoa beans
A cation-exchange HPLC column was evaluated for the analysis of sugars (sucrose, glucose, fructose), acids (citric, lactic and acetic) and ethanol in extracts of cocoa, preserved in a solution of benzoic acid (0,2 % w/v). Optimum sensitivity, precision and selectivity was achieved when the column was operated at a temperature of 25 °C and the combination of a refractive index detector and peak height measured peaks was employed. The limit of detection was 3.5 ng acetic acid, 5.5 ng sucrose, 6.3 ng fructose and lactic acid, 7.3 ng citric acid, 10.5 ng glucose and 12.4 ng ethanol. The extracts of cocoa were stable over a 10 week period, permitting the analysis of large numbers of samples without degradation of the analytes
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Evaluation of the ability of different concentrations of aqueous acetone, aqueous methanol and aqueous acetone: Methanol (1∶1) to extract aflatoxin from naturally contaminated maize
A conventional TLC tank was compared with a specially designed continuous linear development chamber for the ether development phase of the quantitation of aflatoxins by bi-directional High Performance Thin Layer Chromatography (HPTLC). No significant difference was detected in the precision of the method. However, the continuous linear development chamber afforded greater accuracy in aflatoxin determination and required only half the development time and a small fraction of the solvent used in the conventional TLC tank. The ability of different concentrations of aqueous acetone, aqueous methanol and aqueous acetone: methanol (1∶1) to extract aflatoxin from naturally contaminated maize was assessed. With each system, the amount of aflatoxin extracted increased as the ratio of organic solvent: water progressed from 50∶50 to 80∶20 and then decreased or remained constant when the composition of the extraction solvent was altered to 90∶10. 80% aqueous acetone was found to extract 27% more aflatoxin than the corresponding aqueous methanol with the mixed solvent system extracting an intermediate amount of toxin. Clean-up of 80% aqueous acetone extracts of maize by elution through phenol (PH) bonded-phase cartridges resulted in poor aflatoxin retention when the proportion of acetone in 5 ml aliquots of extract was greater than 70%. This could be increased to 100% retention by the addition of an equal quantity of methanol prior to dilution with 1% aqueous acetic acid and elution through the cartridge
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Understanding losses of provitamin A after drying and storage of orange-fleshed sweetpotato (Ipomea batatas)
[Draft Abstract - from Oral Presentation]
Biofortified orange-fleshed sweet potato (OFSP) is being promoted to tackle vitamin A deficiency, a serious public health problem affecting children and pregnant/lactating women in sub-Saharan Africa. The aim of the study was to quantify and understand the factors influencing provitamin A losses in OFSP dried chips. Losses were determined after drying and storage. A preliminary pilot-scale study demonstrated that carotenoid levels were not significantly different after either solar or sun drying. Field conditions using locally-promoted varieties in Uganda and Mozambique showed losses associated with drying were less than 40%. Flour made from OFSP could therefore be a significant source of provitamin A. In contrast, storage of chips at room temperature in Uganda for four months resulted in high losses of pro-vitamin A (ca. 70% loss from the initial dried product). Low-cost pretreatments, such as blanching, antioxidants and salting, did not improve carotenoid retention during storage. To understand the cause of the losses, dried sweet potato chips were stored under controlled conditions of temperature (10; 20; 30; or 40ºC), aw (0.1; 0.3; 0.5 or 0.7) and oxygen (0 [under nitrogen]; 2.5; 10 or 21% [air]). Losses in provitamin A were the least during storage at the lowest temperature and oxygen level and at the highest humidity level. Enzymatic catabolism of beta-carotene in the flour was considered unlikely because of low peroxidase activities at low water activities and the loss of peroxidase activity during storage
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Improvement of the hygienic quality of wet 'fufu' produced in South West Nigeria
To improve the hygienic quality condition of wet ‘fufu’, an indigenous fermented cassava product produced in South-West Nigeria, the processing facilities were upgraded and GMP implemented before HACCP application in processing plants in Abeokuta. The effectiveness of the GMP and HACCP was assessed by monitoring the environment and ‘fufu’ production. Air sampling and swabbing of equipment surfaces revealed a microbiota which was consistent with the fermented product. The results before application of GMP and HACCP showed the predominance of Staphylococcus aureus in the wet ‘fufu’ samples ranging between 1.1 × 104 cfu/g and 2.5 × 105 cfu/g. Monitoring after application showed that the raw materials, products, processing parameters conformed to the critical limits within which the safety of the food product would be ensured. This was confirmed by the results of laboratory analysis of raw materials, intermediary and final products. Escherichia coli, Staphylococcus aureus, and Salmonella were not detected in any of the finished product. Application of GMP and HACCP was therefore found to be effective as a quality management system for assuring the safety of traditionally processed wet ‘fufu’
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Identification of hazards and critical control points (CCP) for cassava fufu processing in South-West Nigeria
A hazard analysis survey of wet fufu processing was carried out for Wve processors around Abeokuta. This analysis consisted of observing the raw materials and environment, watching all steps of the processing, recording pH during steeping/fermentation, and collecting of samples from diced cassava, washed cassava, soaked cassava and wet fufu for total viable count, Coliform, Staphylococcal and Bacillus counts. The pH of steeping/fermentation for the processors varies between 4.08 and 4.58. The total viable count increases with increase in pH level of the wet fufu and Coliforms, Bacillus cereus and Staphylococcus aureus were isolated from the wet fufu. The presence of Coliforms, S. aureus and B. cereus indicates that the processing is carried out in a highly contaminated environment. Education of processors on the hazards, critical control point (CCP) and the importance of hygienic environment is imperative. Therefore, control measures and proper monitoring procedures for wet fufu processing are suggested
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Institutional lessons from the partnership to improve food safety management and livelihoods of street food vendors and consumers in Ghana
The growth in urban populations in Ghana offers both opportunities and risks for resource-poor groups in urban and peri-urban environments. One important opportunity has been the increase in sale and patronage of street-vended foods (SVFs). However, the livelihoods of these street-food vendors, their raw material input suppliers as well as the health of consumers could be jeopardized if problems of food safety are not addressed. This paper emanates from a project executed in 1999/2000 to establish whether food hazards occur in some popular Ghanaian foods sold along the streets of Accra and establish the contributions street-vended foods were making to the economy of Ghana. The coalition team formed was made up of partners from different interest groups. Conflicts resulting from vested interests involving key coalition partners in the project became evident and were addressed. A key lesson from the project is that while key partners may have all the technical capabilities to ensure the success of the project, their poor inter-personal relationships may present a major setback to the progress, timely execution and realization of the project’s goals. The ability of coalition members and the project leaders to effectively manage such conflicts was a key step in realizing the success of the project. Finally, it was also learnt that an unwieldy size of partnership impedes the smooth execution of the project