A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science. Johannesburg, 2014. / Aromatic plants and oils have been used for thousands of years in perfumes, and cosmetics and for their culinary and medicinal purposes. The essential oil from Centella Asiatica growing specifically in South Africa has many therapeutic uses and is used to treat various diseases. Different extraction methods were used on the leaves of Centella Asiatica and the composition of each sample of oil obtained was analysed to see how the composition of each sample is affected. The methods of extracting were optimised specifically for Centella Asiatica. The different extraction methods used were steam distillation, water distillation, solvent extraction and soxhlet extraction. Steam and water distillation were preformed with three different apparatus to compare the efficiency of the extraction and the affect on composition of the oil. It was found that steam distillation using the apparatus described by the British Pharmacopedia Volume IV was the most sufficient apparatus to use to obtain the greatest yield of oil. Soxhlet extraction was found to be the worst extraction method for volatile compounds The optimised parameters for extraction of essential oils from Centella Asiatica using this apparatus were 100 g of leaves at a distillation rate of 2/3 ml min-1 for 75 minutes using 0.4 ml of xylene initially. It was also necessary to perform a 30 minute initial distillation with no plant matter. Steam distillation with this apparatus was found to yield the best quality oil. The major constituents that were found in all the methods were α-carophyllene, carophyllene and germacrene D. There were some similarities found in the compositions of the essential oil between extraction methods in terms of the constituents found. However the abundance of those constituents varied between extractions. Each constituent has a different therapeutic effect. Therefore if an extraction method were to be chosen to extract a some specific constituent like germacrene D and α-carophyllene, steam distillation with the apparatus described by the British Pharmacopedia should be used. However if an extraction method were to be used to extract carophyllene, water distillation should be used. The essential oil extracted using steam distillation yielded a greater amount sesquiterpenoid hydrocarbons. However monoterpenoid hydrocarbons were present in greater amount in the essential oil extracted using water distillation. In the essential oil extracted from Centella Asiatica, 43 constituents were identified from steam distillation extraction representing 98.60% of the composition of oil and 54 constituents representing 98.29% from water distillation extraction. It was found that from steam distillation using fresh leaves compared to dry leaves extraction a greater number of constituents were identified. Salting out was also used for extraction and compared to water distillation and it was found that the salting-out extractions yielded a greater amount of oxygenated polar compounds. A commercial oil of Centella was also analysed and compared to the natural oil. It was found that the commercial oil was a synthetic oil and its composition was completely different from the natural oil and therefore synthetic oils cannot be used therapeutically for substitutes for natural essential oils. Centella Asiatica prefers to grow in damp environments, therefore they are extremely prone to pollution. This was found to also affect the chemical composition of the oil obtained since the soil quality of where the plants were growing was important. This was investigated by spiking the soil of some Centella asiatica plants with chromium(VI), mercury(II) and lead(II). It was found that Centella Asiatica can store heavy metals in the leaves. Since it is a medical plant with many therapeutic uses, this is causes great concern about heavy metal contamination of herbal raw materials of Centella Asiatica. This also highlights the importance of good quality control on Centella Asiatica, so that heavy metals are not ingested. The people in the rural areas who use it as a raw plant for herbal preparations could be at risk of ingesting heavy metals if grown in a polluted area.

Mémoire (M.P.M.O)-- Université du Québec à Chicoutimi, 1991. / Bibliogr.: f. [113]-118. Document électronique également accessible en format PDF. CaQCU

The ability of essential oils (EO) to manipulate the intestinal microbiota may potentiate their application in food as nutraceutical and as prophylactic agents for colonic disease. Little is known about the influence of EO on gut bacteria, the mechanism of their antibacterial action and genotoxicity to the host. Here, the antibacterial activities of EO in pure and in a mixed faecal culture were investigated. These antibacterial activities were further studied to compare the selective nature of EO and their effects on membrane integrity. The growth of gut pathogens and commensals was inhibited in a dose-dependent manner in pure culture, with most of the pathogens, Escherichia coli O157:H7, Clostridium difficile, C. perfringens and Salmonella typhimurium are sensitive to nerolidol, thymol, eugenol and geraniol at a half maximal inhibitory concentration (IC50) of 50-500 ppm. These concentrations of EO and mainly nerolidol were also inhibitory to some gut commensals, in particular affecting Faecalibacterium prausnitzii adversely in pure culture. In contrast, in the mixed culture system beneficial groups of bacteria, including F. prausnitzii, as determined by qPCR of 16S rRNA genes were not affected. Thymol and geraniol at 500 ppm suppressed the growth of total bacteria, resulting in minimal fermentation. A lower dose of 100 ppm of EO compounds was effective in suppressing the pathogen, C. difficile with no concern for commensal bacteria or their fermentation products, acetate, propionate and butyrate. This study also discovered that the proteome of commensal, Faecalibacterium prausnitzii and pathogenic gut bacteria, Escherichia coli, in response to EO compounds are affected differently. Thymol and eugenol down-regulated virulence factors in E. coli. The tested EO compounds were not genotoxic in the comet assay at non-toxic doses. Differential effects of EO compounds on gut pathogens and commensals and their non-toxicity but geno-protective properties could be applicable in improving gut health in man.

The purpose of this phenomenological study was to understand and describe the educators’ experiences of English learner underachievement. The overall aim was to discover and illuminate the essences of this phenomenal experience. The essences embody what is immanent and universal to the phenomenon, what makes the phenomenon the way it inherently is, and what cannot be removed from the phenomenon. This study sought to reveal the general essential features educators’ experiences of English learner share. Furthermore, it was an attempt to arrive at a deeper understanding of the world of everyday human experience. The school system where the study took place is located in southeast Georgia, United States. The group of elementary, middle, and high school educators who participated in the study consisted of eight professional women of diverse cultural backgrounds. All of them had extensive experience of working with English learners in the environment where English was the primary medium of instruction. Data were collected using in-depth interviews and essays. Participant confidentiality was maintained throughout the data collection and analysis. The collected data were organized and analyzed using Moustakas’s modified version of the Stevick-Colaizzi-Keen method that utilizes the processes of the epoché, phenomenological reduction, imaginative variation, and synthesis. Several textural and structural categories emerged from the analysis of the data. The textural thematic categories included: underachieving English learner performance in school, emotional and psychological barriers, language and cultural change, prior educational experience, family’s socioeconomic status and parental involvement, educational practices and teacher attitudes. The structures underlying the educators’ experience of English learner underachievement were represented through evaluation, observation, communication and interaction, development of professional awareness and accountability, examination of students’ backgrounds, professional collaboration, and examination of educational practices. The totality of what the educators experienced in relation to English learner underachievement reveals that no aspect or quality of this phenomenon can be singled out to prevail in this phenomenal appearance. What makes the phenomenon of English learner underachievement intricately complex is its multi-dynamic character which emerges amidst educational, cultural, and socioeconomic inequities. English learner underachievement is ingrained in the structures of school and society. The key findings from the study suggest that educators need to create effective learning situations to accommodate individual needs of underachieving English learners. Similarly, educators need extensive support from the school, district, and policy in ways that help them gain professional knowledge of approaches, strategies, and programs to provide quality education to all English learners. The study has contributed to the overall understanding of the phenomenon of English learner underachievement and drawn attention to the importance of the educator voice in educational decision making.

Orientador: Fabiana Pilarski / Banca: Luiz Eduardo Corrêa Fonseca / Banca: Raquel Regina Duarte Moreira / Banca: Fabiana Garcia Scaloppi / Banca: Eduardo Makoto Onaka / Resumo: Os óleos essenciais (OEs) de plantas são compostos estudados como aditivo alimentar na produção animal há alguns anos, sendo descritos por diversos autores como promotores de crescimento, imunoestimulantes e antimicrobianos. No entanto, os efeitos de sua adição na dieta de organismos aquáticos ainda são pouco conhecidos. No presente estudo, diferentes estratégias de suplementação com diferentes OEs foram testadas. No primeiro estudo, os OEs de Mentha piperita e Melaleuca alternifolia foram incorporados à dieta para tilapia-do-Nilo Oreochromis niloticus por um longo período (2 meses), e os seus efeitos sobre a saúde (parâmetros hematológicos, bioquímicos e imunológicos) e sobre o intestino (morfologia e morfometria) foram avaliados. Em um segundo momento, M. piperita, M. alternifolia, Citrus aurantium, Cymbopogon nardus, Ocimum basilicum e Thymus vulgaris foram testados in vitro contra isolados intestinais (Aeromonas hydrophila, Staphylococcus aureus e Edwardsiella tarda) da tilápia-do-Nilo para seleção daquele com maior capacidade de modular a microbiota dos peixes. O OE de Thymus vulgaris foi aquele que apresentou a maior atividade contra as bactérias testadas. Em um estudo final, o OE de Thymus vulgaris foi incorporado à dieta e fornecido por 15 dias à tilápia-do-Nilo e o efeito sobre a saúde, intestino, e também sobre a população de bactérias do gênero Bacillus no intestino foi avaliado. O primeiro experimento demonstrou que a M. piperita e a M. alternifolia foram capazes ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Essential oils (EOs) of plants are compounds studied as food additive in animal production a few years ago. They have already been described by several authors, as growth promoter, immunostimulant and antimicrobial. However, the effects of its addition on the diet of aquatic organisms are still poorly understood. In the present study, different supplementation strategies with different EOs were tested. In the first study, the EOs of Mentha piperita and Melaleuca alternifolia were supplied for a long period (2 months) in the diet of Nile tilapia Oreochromis niloticus, and aspects of health (hematological, biochemical and immunological parameters) and intestine (morphology and morphometry) were evaluated. In a second moment, M. piperita, M. alternifolia, Citrus aurantium, Cymbopogon nardus, Ocimum basilicum and Thymus vulgaris were tested in vitro against the intestinal isolates (Aeromonas hydrophila, Staphylococcus aureus and Edwardsiella tarda) from Nile tilapia to select the one with the greatest capacity to modulate the microbiota of fish. Thymus vulgaris EO was the one that presented the highest activity against the bacteria tested. In a final study, the Thymus vulgaris EO was provided for 15 days in the diet of Nile tilapia where its effects on the health, intestine and on the population of bacteria of the genus Bacillus were evaluated. In the first experiment, it was shown that M. piperita and M. alternifolia were able to immunostimulate components of fish humoral respon... (Complete abstract click electronic access below) / Doutor

Use of electronic cigarettes (e-cigarettes) is rapidly growing around the world. E-cigarettes are commonly used as an alternative nicotine delivery system, and have been advocated as generating lower levels of harmful chemicals compared to conventional cigarettes. Cigarette smoke-like aerosols are generated when e-cigarettes heat e-liquids. The main components of e-cigarette liquids are propylene glycol (PG) and glycerol (GL) in a varying ratio, plus nicotine and flavor chemicals. Both PG and GL are considered safe to ingest in foods and beverages, but the toxicity of these chemicals in aerosols is unknown. Current studies of e-cigarettes have mainly focused on dehydration and oxidation products of PG and GL. In this study, the other degradation products that can be generated during the vaping process are discussed. In addition, the gas/particle partitioning of chemicals in vaping aerosols is determined. This work finds that the formation of benzene in electronic cigarettes depends on the wattage, types of coils, and devices. To simulate commerical e-cigarette liquids, mixtures containing equal parts of PG and GL by volume were made with the following added components: benzoic acid (BA), benzoic acid with nicotine (Nic), benzaldehyde (BZ), band enzaldehyde with nicotine. PG only, GL only, and PG and GL mixtures were also made for comparison. The data presented here demonstrate that more benzene is generated as the wattage of a device increases. The results also seem to support the importance of ventilation in the generation of benzene. More benzene is generated from the mixtures containing benzoic acid when using the EVOD device with a smaller vent. However, benzaldehyde yields more benzene when using the Subtank Nano device with a larger vent. Findings also indicate that more benzene is produced from GL rather than PG. This thesis also addresses the chemical formation pathways of degradation compounds found in the aerosols formed from isotopically labeled e-cigarette liquids. Mixtures of both 13C-labeled and unlabeled PG as well as GL were made. The mixtures were vaped and gas-phase samples were collected to determine which chemicals were in the gas-phase portion of the aerosols. With the use of GC/MS methods, these isotopic labeling experiments provided evidence that the majority of the benzene, acetaldehyde, 2,3-butanedione, toluene, xylene, acrolein, and furan found in e-cigarette aerosols originates from GL in the PG plus GL mixtures. It was also shown that the majority of propanal is derived from PG: while hydroxyacetone can be formed from both PG and GL. Possible mechanisms for the formation of acetaldehyde, benzene, 2,3-butanedione, toluene, and xylene formation are proposed. Last, this study investigated the gas/particle partitioning of nicotine and flavor-related chemicals in e-cigarette fluids. The gas/particle partitioning behavior of chemicals in e-cigarettes fluids is highly dependent on the chemical volatility. A total of 37 compounds were examined. The target compounds were divided into 3 groups based on their vapor pressures: high, medium, and low. Headspace gas samples were collected and analyzed to determine the concentration of a compound in equilibrium with the liquid phase. The gas and liquid concentrations were used to calculate the gas/particle partitioning constant (Kp) for each compound. In an e-cigarette aerosol, volatile compounds have smaller Kp values and tend to be found in greater proportion in the gas-phase, whereas the less volatile compounds are likely to stay in the particle phase. General agreement with theory was found for compounds with known activity coefficients in PG and GL, indicating that theory can be used to predict Kp values for other compounds.

Logging and forest thinning operations generate large amounts of residues in the form of small trees, branches and foliage that are usually left on the ground to decay or are burned. These resources are readily available, but it is uneconomical to remove them from the forest. The potential utilization of these resources was investigated for western juniper. This species is invading rangeland in the Interior West, altering the ecology of the land, and farmers are being encouraged to remove it. However, limited markets for the wood make removal costly. Developing uses for other parts of the stem could make removal more economically attractive. Western juniper foliage and twigs were steam distilled to obtain essential oils which were tested for their activity against subterranean termites and fungi. Residues from the steam distillation were pretreated with dilute sulfuric acid and digested with enzymes to determine their digestibility. The goal was to determine if an integrated operation involving steam distillation to remove essential oils, followed by enzymatic digestion of extraction residues was feasible. Essential oil recovery from foliage averaged 0.77% wet weight, while yields from twigs were about 0.13% wet weight. Foliage essential oil showed high antifungal and termiticidal activities at the concentrations tested. Total sugar yields from foliage extraction residues (40-55%) were higher than those obtained from branchwood residues (15-25%). The highest yields were obtained at 121°C and 1 hour pretreatment in 1% sulfuric acid. These results show that an integrated operation involving steam distillation of western juniper foliage to remove essential oil and enzymatic digestion of extraction residues is technically feasible. Additional work to determine the optimum distillation and pretreatment conditions for foliage would be needed. / Graduation date: 2012

Radish anthocyanin extract has potential as a natural colorant because of its pigment stability and attractive red hue. Presence of undesirable aroma compounds could limit its applications in foods. The pungent principle of radish, 4-methylthio-3-butenyl isothiocyanate (MTBI), is produced enzymatically upon cell injury from its glucosinolate precursor, 4-methylthio-3-butenyl glucosinolate (MTBG), and undergoes subsequent degradation to produce a number of volatiles. To evaluate the potential of flavor formation, juices were prepared from winter and spring radish cultivars. Whole radishes, peels and flesh, as well as radish extracts, were analyzed for glucosinolates and isothiocyanates. Aroma intensities of radish juice extracts were evaluated using sensory analysis. MTBI was monitored by HPLC (detection level 160 ppb). MTBG was extracted from freeze-dried radish tissue with boiling methanol, purified by anion exchange and enzymatically desulfated. DesulfoMTBG was quantified by HPLC, using desulfosinigrin as internal standard. Identification was performed by fast atom bombardment and electrospray mass spectroscopy. MTBI formation was higher in winter than in spring cultivars (1.5-2.8 and 0.8-1.3 mg/100g fresh weight, respectively), and higher in flesh than in peels. MTBG ranged from 30-65 mg (spring cultivars) to 260-320 mg/100g fresh weight (winter cultivars) with greater concentration in peels than in flesh. Isothiocyanates and glucosinolates were not detected in radish juices. Overall aroma intensities of radish juice concentrates, diluted to 150, 300, 600 and 1200 mg anthocyanin/L in water, were rated using a 16-point scale. Radish concentrates from cultivars Fuego (pigmented peels) and Red Meat Takii (whole red flesh) were compared to commercial red cabbage and radish colorants. Aroma intensities followed first order relationships with anthocyanin concentrations. The commercial colorants were rated slight to moderate, while radish extracts (Fuego and Takii) were rated moderate to large. The aroma intensity of red flesh radish extract was more potent than those prepared from radish peels. Further work includes development of purification techniques which would provide an odorless aqueous extract. / Graduation date: 1997

Thesis (M. Sc.(Agric))(Horticulture)-University of Pretoria, 2005. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Hops (Humulus lupulus L.) are primarily used to provide specific characteristics to beer, such as bitterness, aroma, flavor, and microbial stability. The chemical composition of hops, relative to how they are used during the brewing process, dictates the expression of these characteristics. Of the raw ingredients that go into making beer, hops are perhaps the most costly. Considerable resources are required to grow quality hops, and therefore, brewers and hop growers alike have a common goal of obtaining the highest quality hops possible. However, quality can be a relative term. While it is commonly agreed upon that high brewing values, such as α-acids and essential oil content, and robust structural integrity are indicators of quality hops, there are many opinions of the ideal aroma. Changes in the chemical composition of hops during plant maturation are a dynamic process requiring a comprehensive, in-depth chemical and sensory analysis in order to maximize the characteristics of interest to brewers. The complex aroma chemistry associated with hops in beer has been a confounding variable for the practical brewer, and a deeper understanding of hop aroma development during cultivation is needed. The effect of harvest date, location, and cultivar on key chemical components of Willamette and Cascade hops was investigated for the 2010 and 2011 growing seasons. Hops were harvested at 3 time points (Early, Typical, and Late), within a 3-week interval from 2 different farms in the Willamette Valley, Oregon. A split-plot experimental design for each cultivar was used; each farm represented a main plot and harvest years were designated as subplots. American Society of Brewing Chemist standard methods of analysis were used to measure moisture content, hop acids and their homologs, Hop Storage Index, total essential oil content and volatile profile by GC-FID. Additionally, difference testing, descriptive analysis, and consumer acceptance testing was conducted using beers brewed with either Typical or Late harvested Cascade hops from the 2010 harvest year. The response of analytes was dependent on the cultivar being examined, its location within the Willamette Valley, as well as days until harvest. Hop acids did not change appreciably during plant maturation for the period examined, while hop oil content increased hyperbolically to a plateau as the hops aged on the bine. Increases in oil quantity were strongly correlated (r > 0.90) with increases in α-pinene, β-pinene, myrcene, limonene, methyl heptanoate, and linalool concentrations. For Cascade, α-pinene, β-pinene, myrcene, limonene, ρ-cymene, caryophyllene, E, β-farnesene, and humulene all increased from Early to Typical points but no increase was observed between the Typical and Late time point. Linalool and methyl heptanoate increased between each time point while citral and humulene epoxide differed between Early harvest and Late harvest, but not between Early and Typical or Late and Typical harvests. For Willamette hops, α-pinene, β-pinene, myrcene, limonene, ρ-cymene, and linalool all increased between each time point. Caryophyllene, E β-farnesene, humulene, farnesol and citral all increased from Early harvest to Typical harvest but no difference was observed between Typical and Late. Clear sensory differences were found between beers brewed with Typical harvest Cascade hops and Late harvest Cascade hops, in terms of difference testing, descriptive analysis and consumer preference tests. / Graduation date: 2013