Thesis (M. Sc.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Oct. 20, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Plant Science, Department of Agricultural, Food and Nutritional Science, University of Alberta." Includes bibliographical references.

Thesis (Ph.D.)(Food Science)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2008. / Submitted by Caroline Silva (krol_bilhar@hotmail.com) on 2012-09-13T19:06:33Z No. of bitstreams: 1 avaliao da atividade antifngica e antimicotoxinas de extratos de farelo de arroz cebola e microalga chlorella.pdf: 988335 bytes, checksum: 8413be9e7b4208c1612064781396a048 (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2012-09-24T22:59:35Z (GMT) No. of bitstreams: 1 avaliao da atividade antifngica e antimicotoxinas de extratos de farelo de arroz cebola e microalga chlorella.pdf: 988335 bytes, checksum: 8413be9e7b4208c1612064781396a048 (MD5) / Made available in DSpace on 2012-09-24T22:59:35Z (GMT). No. of bitstreams: 1 avaliao da atividade antifngica e antimicotoxinas de extratos de farelo de arroz cebola e microalga chlorella.pdf: 988335 bytes, checksum: 8413be9e7b4208c1612064781396a048 (MD5) Previous issue date: 2008 / A contaminação fúngica acarreta alterações na qualidade nutricional e no valor econômico dos produtos alimentícios podendo causar danos patológicos em plantas, animais e humanos. A identificação da atividade antifúngica e antimicotoxinas, em extratos de diferentes fontes que exibem propriedades de inibir naturalmente o crescimento de fungos e subseqüente produção de micotoxinas (metabólitos secundários produzidos por fungos toxigênicos), abre a perspectiva de empregar de forma mais eficiente os tecidos vegetais empregando-os como conservadores naturais. Entre os compostos com propriedades inibidoras de crescimento fúngico e produção de micotoxinas, naturalmente presentes em alimentos, destacam-se os compostos fenólicos, que por sua estrutura química dificultam a atividade de enzimas metabólicas de microrganismos. As matérias-primas escolhidas foram: o farelo de arroz, a cebola e a microalga Chlorella phyrenoidosa. Aos três tecidos são atribuídas propriedades funcionais, sendo que os dois primeiros são abundantes na região sul e comercializados com baixo valor agregado. A chlorella é empregada em dietas especiais como fonte de compostos bioativos especialmente aminoácidos essenciais e compostos antioxidantes. Este trabalho teve como objetivo determinar o teor de compostos fenólicos, a atividade antifúngica sobre o desenvolvimento dos fungos dos gêneros Rhyzopus sp., Aspergillus oryzae, Aspergillus flavus, e Fusarium graminearum e a atividade antimicotoxinas sobre o fungo Aspergillus flavus, em extratos de farelo de arroz, cebola e Chlorella. Os compostos fenólicos da cebola foram extraídos em três sistemas solventes: aquoso, metanólico e acetato de etila. Os compostos fenólicos do farelo de arroz e da chlorella foram extraídos com metanol, sendo quantificados colorimetricamente com reagente de Folin-Ciocalteau. O conteúdo de fenóis totais nos vegetais variou de 68 μgfenóis.g-1 em extrato aceto-etílico de cebola a 3012 μgfenóis.g-1 em extrato aquoso de cebola. Os extratos foram triados sobre os fungos Rhyzopus sp e Aspergillus oryzae que foram os modelos para estimar a inibição de crescimento fúngico. Esporos de Aspergillus flavus foram utilizados para estudar o efeito inibidor da produção de aflatoxina B1 e B2. Os extratos testados apresentaram algum grau de inibição do desenvolvimento fúngico, sendo a chlorella a que apresentou maior inibição em relação aos outros extratos, em todos os fungos testados, chegando a 31% de inibição/μg fenol total. Após o 7°, 14° e 21° dia de incubação foram realizadas extrações de micotoxinas do meio de crescimento pelo método adaptado de TANAKA et al., (2000). O extrato fenólico de Chlorella inibiu totalmente a produção de micotoxinas em relação ao controle. Estes resultados mostram que a ação antifúngica está naturalmente presente em alguns tecidos vegetais e que encontrar a forma de extraí-los e aplicá-los como conservadores de alimentos é muito promissor para agregar valor aos alimentos, principalmente aqueles de baixo valor comercial. / The fungal contamination cause alterations in nutritional quality and economic value of food products and can cause pathological damages in plants, animals and humans. The identification of the antifungal activity and antimycotoxin in extracts of sources different that show properties of naturally inhibiting the fungal growth and subsequent mycotoxins production (metabolites secondary produced by toxic fungal), open the perspective of employing in the more efficient form the vegetable tissue employing them like natural conservatives. Between compounds with properties inhibiting of fungal growth and mycotoxins production, naturally present in foods, stand out the phenolics, what for your chemical structure make difficult the activity of metabolic enzymes of microrganisms. The chosen raw materials were: the rice bran, the onion and the microalga Chlorella phyrenoidosa. To three tissues functional properties are attributed being that two first ones are abundant in the south region and marketed with low collected value. The Chlorella is employed in special diets like source of bioactives compounds and antioxidant compounds. This objective study was determine the tenor of phenolics compounds, the antifungal activity on the development of the fungal Rhyzopus sp, Aspergillus oryzae, Aspergillus flavus and Fusarium graminearum and antimycotoxin activity on the fungal Aspergillus flavus, in extracts of bran of rice, onion and Chlorella. The phenolic compounds of the onion were extracted in three solvent systens: aqueous, methanolic and ethila acetate. The phenolic compounds of the bran of rice and of the Chlorella were extracted with methanol, and quantified with reagent of Folin-Ciocalteau. The total phenolics levels in vegetables ranged between 68 μgphenolicg-1 in aceto-ethylic extract of anion and 3012 μgphenolic g-1 in aqueous extract of onion. The extracts was used in antifungal tests against strains of Rhyzopus sp and Aspergillus oryzae that were the models to appreciate the inhibition of fungal growth. Spores of Aspergillus flavus were used to study the inhibiting effect of the aflatoxins B1 and B2 production. The tested extracts presented some degree of inhibition of the fungal development, being the Chlorella Who presented tested bigger inhibition regasding other extracts, in all the fungal, is reaching 31% of inhibition/μgphenolic . After 7°, 14 and 21° Day of incubation were carried out extractions of mycotoxins from growth médium were determined by TANAKA et al., method (2000). The phenolic extract of chlorella inhibited totally the mycotoxins production regarding the control. These results show that the antifungal activity is present naturally in some vegetable tissues and that to find the formo of extracting to apply as conservatives of foods is very promising to values collect to the foods, principally those of low commercial value.

M.Tech. (Biomedical Technology) / Malawi is located in the south eastern Africa. It is a landlocked country covering an area of 118,484 Square Kilometres (45,747Sq.Miles) of which 20.6% is water. It is bordered with Zambia to the north-west, Tanzania to the north and Mozambique surrounding it on the south, east and west (refer map of Malawi on page 2). Malawi is one of the sub-Sahara heavily populated countries, having a population of about 13 million people of which about 80% live in the rural areas relying on small scale farming. The country is divided into three regions, south, centre and north and these regions are further divided into districts. The southern region has most districts and is the most heavily populated. Malawi’s economy heavily depends on agriculture. Cash crops such as tobacco, tea and sugar canes are grown by commercial farmers while smallholder farmers grow a variety of crops such as tobacco, coffee, beans, fava beans, cotton, rice, sorghum, soybeans, groundnuts, cassava, potatoes, wheat, millet, peas, bananas, citrus fruits, sugar canes, vegetables and maize which is the main staple food. Malawi has a subtropical climate with the rainy season starting from mid October up to April and the dry season is from May to October. During the dry season it is hot and humid in most parts of the country especially along the lake and the lower Shire valley, while the rest of the country can be cold at night with temperatures between 5ºC and 14ºC. The southern region has the highest annual rainfall and is humid most part of the year. This is where many tea plantations are and the climate allows growth of almost all types of crops and fruits. Most Malawians consume home grown unprocessed food commodities. There are only commodities are imported, mainly from South Africa. Malawi is self reliant on maize but when drought strikes, Malawi is forced to import from neighbouring countries or from South Africa and other countries as was the case in 2004 and 2005

Submitted in part fulfilment of the requirements for the Degree of Master of Technology: Biotechnology, Durban Institute of Technology, 2004. / Various methods have been developed for the analysis of Fusarium and its toxins. Advances in molecular biology can lead to efficient characterization of this group of fungi. This study was undertaken to examine random amplified polymorphic DNA, volatile compound production and hydrolytic enzyme production by 19 Fusarial isolates. These techniques were employed to assess their abilities in differentiating Fusarium species and F. verticillioides strains and extending the analysis to discriminate toxin producing capabilities amongst these fungi

M. Tech. / Fusarium species are common contaminants of maize and are also capable of producing mycotoxins, in particular the fumonisin. These are implicated in animal and human mycotoxins fumonisin B1 (FB1) for example, has been associated in the aetiology of oesophageal cancer in South Africa and other parts of the world, i.e., China and Iran. Because maize is the staple diet of the South African rural population, this study was designed with the aim of monitoring Fusarium spp. and FB1 in the food of rural people of Venda, Limpopo province of South Africa, during the course of processing maize into porridge which gave a means of estimating dietary exposure to this mycotoxin. Measurement of fumonisin in the excreta of these people allowed a determine of the extent to which FB1 the body is actually exposed to the mycotoxin.Fumonisin B1 has been identified as a major fungal contaminant on maize, especially in the home grown crops intended for human consumption. Thus the rural population of Limpopo Province is at high risk from FB1 exposure and it is therefore of importance to assess this exposure by the analysis of suitable samples.It can be seen that levels of FB1 in maize from Venda are quite high, as several of these samples had exceeded levels above 1750 μg/kg as recommended as maximum tolerance levels by theEuropean Commission. It is equally seen that a much higher proportion of this mycotoxin was destroyed by processing maize to porridge. And because porridge and other maize-based products are usually consumed on a daily basis, the low levels found in the present study must not be under-estimated, as such levels may accumulate over time and cause more severe chronic effects in humans. When setting daily tolerable levels of FB1 in foods in South Africa, it is imperative to take into account the food habits, especially those within the rural communities

M.Tech. (Biotechnology) / Please refer to full text to view abstract

Several countries have enacted regulations on tolerance limits for common mycotoxins because of the hazardous nature and widespread occurrence of these fungal secondary metabolites in agricultural commodities. Screening of agricultural commodities destined for animal consumption for the presence of mycotoxins is now becoming a prerequisite in several countries as a means of minimizing ingestion of these toxins. Silage samples were analyzed for pH, % dry matter (DM) content, and the presence of total fungi, yeasts and the types of lactic acid bacteria present. The samples were also analyzed for mycotoxins that have been reported to commonly occur in silage. The pH of the samples was found to be acidic ranging from pH 3.4 to 4.7, with few samples having pH values above 6. There was a significant difference in the % DM content amongst the sampling regions. There was no significant difference in the extent of fungal contamination amongst the different regions. Aspergillus fumigatus was the predominant species from all the samples. Most of the yeast species were isolated from the Bergville region. The yeast species isolated from all samples were Trichosporon, Cryptococcus and Candida species, which are all regarded as nonlactate fermenters. Lactobacillus plantarum and Lactobacillus buchneri were the only two lactic acid producers isolated from the samples. Aflatoxins, citrinin and patulin were the most predominant toxins in the samples. Ochratoxin A and deoxynivalenol was not detected in all samples using thin layer chromatography, while the latter two toxins were only detected in two samples using VICAM fluorometry. The level of fumonisins that was found in the forage crops used for silage production was fairly low with the highest level being 9.36 ppb. Most of the mycotoxin extracts were found to reduce the % cell viability of human lymphocytes after 18 hours of incubation as determined by the MTT assay. / Professor Mike Dutton Mr. F. E. Van Zyl

M.Tech. / Mycotoxins are toxic substances naturally produced by moulds (fungi) that may contaminate agricultural commodities by growing on grain or feed. These moulds produce in a variety of dangerous mycotoxins, such as aflatoxin, fumonisin, deoxynivalenol (DON), ochratoxin, and zearalenone, and may induce acute or chronic effects (carcinogenic, mutagenic, tetragenic and oestrogenic) in humans and animals if ingested. Wheat is an important cereal grown in most provinces of South Africa and yet little is known with respect to incidence of its infection with fungi, contamination with mycotoxins or what carry over of these toxins is into human food. The purpose of this project is to investigate the incidence of fungi and mycotoxins in samples of wheat taken from specified areas in South Africa with a view to finding out if there is indeed a problem and, if so, what would be its impact on the industry and consumers. This pilot project would then form the basis for further studies in other geographical areas and how wheat-based foods for human consumption are affected. Mycotoxins have probably been present in food and feed since the beginning of human existence. Some of their effects have been known for hundreds of years. The technology to detect and chemically characterize them has only really developed in the last 40 years, particularly since 1980. Very small quantities of many of the important mycotoxins can now be detected and accurately measured in foods and feeds. In addition to those already known, many others are known to exist, but have not yet been chemically characterized. Scientists are now identifying toxic compounds in food faster than the information can be processed. However, to maintain perspective, it must be remembered that these substances have always been there, that humans have always been eating the food in which they occur and in the case of many substances, only the dose makes the poison. This study investigated the presence of toxigenic fungi and mycotoxins in wheat and wheat-based products, and also did a pilot study on a few heavily contaminated field wheat (HCFW) samples. Fusarium species dominated the mycological contamination at 40 to 65%, Aspergillus 45%, Penicillium 41% Mucor and Rhizopus were also detected. Among the Fusarium species isolated, six were identified as F graminearum, F. solani and F. vertillioides-like and F subglutinans. Phoma species were also isolated. Quantitative and qualitative analysis by, multi-mycotoxin screen method and VICAM method to analyze foods and feeds was used. Deoxynivalenol was the most prevalent at 45% incidence in samples with a mean concentration of 4.6ppm, aflatoxins in 12% of the samples with a mean concentration of 1.2ppb, ochratoxin in 16% of the samples with a mean of 1.5ppb, zearalenone in 18% of the samples with a mean of 0.1ppb. Attention was drawn to the potential presence of fumonisin in wheat, where fumonitest VICAM method was used, fumonisins were detected on few samples at very low levels of 1 to 2ppm in commercial wheat, and a high reading of 49ppm was recorded on one of the heavily contaminated field wheat (HCFW) samples. Confirmation of these results was carried out with the use of the liquid chromatography coupled with mass spectrum (LC/MS) and high-pressure liquid chromatography (HPLC) system. These results indicate an incidence of mycotoxin in these products, a recommendation of monitoring for prevention of moulds and mycotoxins is suggested. Since health concerns related to dietary exposure to mycotoxins depend on the levels of mycotoxins in the food as consumed, on the amount of food consumed and on the body weight and physiology state of the individual. Therefore, there is a likely possibility that in South Africa, some of the population is exposed to mycotoxins through consumption of wheat and its by-products.

M.Tech. / Please refer to full text to view abstract