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A concerning situation has developed over the past few years where several tea estates had to close down due to high labour costs and low profitability. Solutions are desperately required to save these estates from further regression and to prevent others from joining their ranks. One solution is to redirect the tea factories from the current production of black tea to producing a value added commodity such as a high quality green tea extract with an increased market value. The aim of this study was to find an economically viable PPO inactivation method that can be implemented in existing tea factories for the production of high quality instant green tea. Further enhancement of quality may then be achieved by high throughput cultivar screening where those with a higher natural catechin to caffeine content will be favourable. Six different PPO inactivation methods (steaming, blanching, fluid bed drying, panfrying, grilling over direct heat and grilling over indirect heat) were explored. Four independent experiments were performed in duplicate with these six methods using fresh tea leaves donated by a tea estate in Tzaneen, South Africa. All samples were dried in a fluid bed drier and milled after PPO inactivation. Biochemical analysis of specific quality parameters followed where extractions from these green tea leaf samples were tested for theaflavin content, caffeine content, flavan-3-ol content, total free amino acid content, colour and taste. The six PPO inactivation methods were compared by data evaluation of the individual quality parameters where certain quality parameters carried a higher weight than others. For the purpose of this project, the catechin to caffeine ratio was the most important quality determinant to yield a high value IGT. Also, to prove effectiveness of the PPO inactivation method, low TF content was compulsory. All PPO inactivation methods explored proved successful in rapidly inactivating PPO enzyme. As hypothesised, a significant difference in biochemical composition is brought about between green teas produced by employing different PPO inactivation methods. Blanching was found to be the most efficient PPO inactivation method as well as the method resulting in the highest catechin to caffeine ratio (16.67:1 for 4 min blanch vs. 5.72:1 for 17 min FBD as determined by HPLC analysis). A freeze dried extract from a 1.5 minute blanched sample (IGT) was compared with foreign IGTs originating from Sri-Lanka, Kenya, China and India by HPLC analysis. A more than two fold greater catechin to caffeine ratio was obtained for the sample originating from the blanching method (9.08:1 vs. 2.81-5.02:1). A high quality, naturally low caffeine, instant green tea can therefore be produced by utilizing the blanching method of PPO inactivation. To allow for inter and intra cultivar screening, tentative identification of novel catechins (digallated catechins) and their HPLC retention times was done using HPLC-ESI-MS/MS. Potential HPLC retention times for EC-digallate were detected at tR 62.0 ± 0.2, 70.7 ± 0.1 and 76.7 ± 0.2 minutes while tR 64.6 ± 0.1 and 65.8 ± 0.1 minutes were detected for EGC-digallate. With this information at hand, cultivars of a higher quality, hence increased economical potential, can be identified upon confirmation by NMR. HPLC-ESI-MS/MS screening coupled with NMR confirmation is to be continued to detect several other novel flavan-3-ols that could not be detected in the 4 IGTs of different origin used in this study. This study gives an overview of the biochemical differences between green tea leaves prepared using six different PPO inactivation methods. The aim of this study was met by identification of the significant increase in quality brought about by PPO inactivation using the blanching method, which is also economical for use in Africa. Blanching of tea leaves caused a significant decrease in caffeine. Therefore, the 1st hypothesis, stating that the six polyphenol oxidase inactivation methods investigated will produce instant green teas with different catechin to caffeine ratios, is accepted. Also, a means to perform large scale screening of individual tea trees in Africa for their novel flavan-3-ol content was provided by tentative identification of these novel catechins by LC-MS. Thus, the 2nd hypothesis, stating that application of LC-MS will aid in the identification of HPLC retention times of compounds (novel catechins) from a crude extract, is also accepted. / Dissertation (MSc)--University of Pretoria, 2009. / Biochemistry / unrestricted

<p>&nbsp / </p> <p align="left"><font face="Times New Roman">Aspalathus linearis (A. linearis), </font><font face="Times New Roman">commonly known as Rooibos tea or Red bush tea and </font><i><font face="Times New Roman">amellia sinensis (C. sinensis) </font></i><font face="Times New Roman">or Black tea are beverages that are consumed throughout the</font><font face="Times New Roman">world. These teas possess antioxidant, immunomodulating and anti-cancer actions. The aim</font> <font face="Times New Roman">of this study was to use <i>in vitro </i>assays to screen Rooibos and Black tea for endocrine</font> <font face="Times New Roman">modulation. </font><font face="Times New Roman">The immune modulating effects of Rooibos and Black tea were investigated using an <i>in vitro</i></font> <font face="Times New Roman">whole blood culture (WBC) assay. Unstimulated WBCs treated with Rooibos tea secreted</font> <font face="Times New Roman">higher levels of IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>than cultures treated with DMSO control. Rooibos treatment of stimulated WBCs resulted in higher IL-6, lower IL-10 and no effect on IFN&gamma / </font><font face="Times New Roman">secretion compared to DMSO treated stimulated WBC. Black tea treatment of stimulated</font> <font face="Times New Roman">WBC resulted in decreased IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>secretion compared to the DMSO treated</font> <font face="Times New Roman">stimulated WBC. </font><font face="Times New Roman">Extracts of Rooibos and Black tea were assessed for phytoestrogens using quantitative </font><font face="Times New Roman">estrogen ELISAs. Both teas contain phytoestrogens. The quantitative ELISAs showed that </font><font face="Times New Roman">Rooibos tea contained significantly lower estrone (E1), estradiol (E2) and estriol (E3) levels </font><font face="Times New Roman">than Black tea. The effects of Rooibos and Black tea on proliferation of the estrogen</font> <font face="Times New Roman">dependant MCF-7 cell line was determined to further characterise the phytoestrogenic</font> <font face="Times New Roman">properties of the teas. Both Rooibos and Black tea extracts caused a significant inhibition of</font> <font face="Times New Roman">MCF-7 proliferation. </font><font face="Times New Roman">This study shows that Rooibos tea and Black tea are beverages that can either stimulate or </font><font face="Times New Roman">suppress the immune system. Also, both teas contain significant levels of phytoestrogens as </font><font face="Times New Roman">determined by quantitative ELISAs. The current study confirms previous reports showing </font><font face="Times New Roman">inhibition of growth in breast cancer cell lines by phytoestrogens. The findings extend </font><font face="Times New Roman">related observations on the anti-carcinogenic potential of the two teas.</font></p>

In this thesis we study three basic issues related to international black tea markets: Are black tea markets integrated? Where is the price of black tea discovered? Are there leaders and followers in black tea markets? We use two statistical techniques as engines of analysis. First, we use time series methods to capture regularities in time lags among price series. Second, we use directed acyclic graphs to discover how surprises (innovations) in prices from each market are communicated to other markets in contemporaneous time. Weekly time series data on black tea prices from seven markets around the world are studied using time series methods. The study follows two paths. We study these prices in a common currency, the US dollar. We also study prices in each country's local currency. Results from unit root tests suggest that prices from three Indian markets are not generated through random walk-like behavior. We conclude that the Indian markets are not weak form efficient. However, prices from all non-Indian markets cannot be distinguished from random walk-like behavior. These latter markets are weak form efficient. Further analysis on these latter markets is conducted to determine whether information among the markets is shared. Vector Autoregressions (VARs) on the non-Indian markets are studied using directed acyclic graphs, impulse response functions and forecast error decomposition analyses. In both local currencies and dollar-converted series, the Sri Lankan and Indonesian markets are price leaders in contemporaneous time. Kenya is an information sink. It is endogenous in current time. Malawi is an exogenous price leader in dollar terms, but it is endogenous in local currency in contemporaneous time. In the long run, Sri Lanka, Indonesia and Malawi are price leaders in US dollar terms. In local currency series, Indonesia, Kenya and Malawi are price leaders in the long run. We use Theil's U-statistic to test the forecasting ability of the VAR models. We find for most markets in either dollars or on local currencies that a random walk forecast outperforms the VAR generated forecasts. This last result suggests the non-Indian markets are both weak form and semi-strong form efficient.

Motivation: A variety of factors including food shortage, poor hygiene and low education levels affects the nutritional status of black women. Women also have a high risk for the development of iron deficiency because they lose iron through menstruation, the birth process and a low intake of iron containing foods. All of these factors contribute to an increased risk for the development of iron deficiency anaemia in women. Objectives: The primary purpose of the study was to investigate the association between tea consumption and iron status of African females in the North West Province. To reach this purpose the specific aims were to (1) assess the iron status of women, (2) determine tea intake, and (3) determine the relationship between tea consumption and iron status, taking into account inhibiting and enhancing factors of iron absorption. Methods: A cross-sectional sample of apparently healthy females was taken from five different strata of urbanisation. The subjects were then further divided into two groups, namely younger women (younger than 45.9 years) and older women (older than 46 years). A sample of 920 subjects was used. Data were obtained from dietary, demographic and additional questionnaires, as well as from the taking of blood samples. This study was a sub-study of the THUSA study. Results: A total of 920 subjects participated of which 69.24% were younger women and 30.76% were older women. Due to missing data, the number of subjects for each parameter differed. The mean serum ferritin as well as haemoglobin concentrations were within normal ranges for both groups. The mean dietary iron intake for both groups was below recommendations. No significant correlations were found between serum ferritin or haemoglobin and total tea intake as well as a variety of other dietary factors. The low haemoglobin concentration group of the younger and older women combined had a slightly higher intake of animal protein and ascorbic acid than the high haemoglobin concentration group. On the other hand, the high serum ferritin concentration group had a significantly higher intake of animal protein than the low serum ferritin concentration group. Conclusion: The results of this study indicated that tea does not have an inhibitory effect on the iron status of the female population of the North West Province. However, the investigation of other studies conducted on the same topic had mixed results. Two of seven studies investigated and this study indicated that tea had no inhibitory effect on iron absorption. These two studies, as well as this study were not done in a controlled environment where certain factors can be controlled for, for example, time of tea intake and milk consumption with tea. The other five studies were, however, conducted in an environment where subjects were given test meals, time of tea consumption was regulated and milk consumption with tea was recorded. The conclusion can, therefore, be made that further studies on the South African population in a controlled environment are necessary to give accurate recommendations to the population. / Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

<p>&nbsp / </p> <p align="left"><font face="Times New Roman">Aspalathus linearis (A. linearis), </font><font face="Times New Roman">commonly known as Rooibos tea or Red bush tea and </font><i><font face="Times New Roman">amellia sinensis (C. sinensis) </font></i><font face="Times New Roman">or Black tea are beverages that are consumed throughout the</font><font face="Times New Roman">world. These teas possess antioxidant, immunomodulating and anti-cancer actions. The aim</font> <font face="Times New Roman">of this study was to use <i>in vitro </i>assays to screen Rooibos and Black tea for endocrine</font> <font face="Times New Roman">modulation. </font><font face="Times New Roman">The immune modulating effects of Rooibos and Black tea were investigated using an <i>in vitro</i></font> <font face="Times New Roman">whole blood culture (WBC) assay. Unstimulated WBCs treated with Rooibos tea secreted</font> <font face="Times New Roman">higher levels of IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>than cultures treated with DMSO control. Rooibos treatment of stimulated WBCs resulted in higher IL-6, lower IL-10 and no effect on IFN&gamma / </font><font face="Times New Roman">secretion compared to DMSO treated stimulated WBC. Black tea treatment of stimulated</font> <font face="Times New Roman">WBC resulted in decreased IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>secretion compared to the DMSO treated</font> <font face="Times New Roman">stimulated WBC. </font><font face="Times New Roman">Extracts of Rooibos and Black tea were assessed for phytoestrogens using quantitative </font><font face="Times New Roman">estrogen ELISAs. Both teas contain phytoestrogens. The quantitative ELISAs showed that </font><font face="Times New Roman">Rooibos tea contained significantly lower estrone (E1), estradiol (E2) and estriol (E3) levels </font><font face="Times New Roman">than Black tea. The effects of Rooibos and Black tea on proliferation of the estrogen</font> <font face="Times New Roman">dependant MCF-7 cell line was determined to further characterise the phytoestrogenic</font> <font face="Times New Roman">properties of the teas. Both Rooibos and Black tea extracts caused a significant inhibition of</font> <font face="Times New Roman">MCF-7 proliferation. </font><font face="Times New Roman">This study shows that Rooibos tea and Black tea are beverages that can either stimulate or </font><font face="Times New Roman">suppress the immune system. Also, both teas contain significant levels of phytoestrogens as </font><font face="Times New Roman">determined by quantitative ELISAs. The current study confirms previous reports showing </font><font face="Times New Roman">inhibition of growth in breast cancer cell lines by phytoestrogens. The findings extend </font><font face="Times New Roman">related observations on the anti-carcinogenic potential of the two teas.</font></p>

Motivation: A variety of factors including food shortage, poor hygiene and low education levels affects the nutritional status of black women. Women also have a high risk for the development of iron deficiency because they lose iron through menstruation, the birth process and a low intake of iron containing foods. All of these factors contribute to an increased risk for the development of iron deficiency anaemia in women. Objectives: The primary purpose of the study was to investigate the association between tea consumption and iron status of African females in the North West Province. To reach this purpose the specific aims were to (1) assess the iron status of women, (2) determine tea intake, and (3) determine the relationship between tea consumption and iron status, taking into account inhibiting and enhancing factors of iron absorption. Methods: A cross-sectional sample of apparently healthy females was taken from five different strata of urbanisation. The subjects were then further divided into two groups, namely younger women (younger than 45.9 years) and older women (older than 46 years). A sample of 920 subjects was used. Data were obtained from dietary, demographic and additional questionnaires, as well as from the taking of blood samples. This study was a sub-study of the THUSA study. Results: A total of 920 subjects participated of which 69.24% were younger women and 30.76% were older women. Due to missing data, the number of subjects for each parameter differed. The mean serum ferritin as well as haemoglobin concentrations were within normal ranges for both groups. The mean dietary iron intake for both groups was below recommendations. No significant correlations were found between serum ferritin or haemoglobin and total tea intake as well as a variety of other dietary factors. The low haemoglobin concentration group of the younger and older women combined had a slightly higher intake of animal protein and ascorbic acid than the high haemoglobin concentration group. On the other hand, the high serum ferritin concentration group had a significantly higher intake of animal protein than the low serum ferritin concentration group. Conclusion: The results of this study indicated that tea does not have an inhibitory effect on the iron status of the female population of the North West Province. However, the investigation of other studies conducted on the same topic had mixed results. Two of seven studies investigated and this study indicated that tea had no inhibitory effect on iron absorption. These two studies, as well as this study were not done in a controlled environment where certain factors can be controlled for, for example, time of tea intake and milk consumption with tea. The other five studies were, however, conducted in an environment where subjects were given test meals, time of tea consumption was regulated and milk consumption with tea was recorded. The conclusion can, therefore, be made that further studies on the South African population in a controlled environment are necessary to give accurate recommendations to the population. / Thesis (M.Sc. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

Magister Scientiae - M.Sc. / Aspalathus linearis (A. linearis), commonly known as Rooibos tea or Red bush tea and Camellia sinensis (C. sinensis) or Black tea are beverages that are consumed throughout the world. These teas possess antioxidant, immunomodulating and anti-cancer actions. The aim of this study was to use in vitro assays to screen Rooibos and Black tea for endocrine modulation. The immune modulating effects of Rooibos and Black tea were investigated using an in vitro whole blood culture (WBC) assay. Unstimulated WBCs treated with Rooibos tea secreted higher levels of IL-6, IL-10 and IFNγ than cultures treated with DMSO control. Rooibos treatment of stimulated WBCs resulted in higher IL-6, lower IL-10 and no effect on IFNγ secretion compared to DMSO treated stimulated WBC. Black tea treatment of stimulated WBC resulted in decreased IL-6, IL-10 and IFNγ secretion compared to the DMSO treated stimulated WBC. Extracts of Rooibos and Black tea were assessed for phytoestrogens using quantitative estrogen ELISAs. Both teas contain phytoestrogens. The quantitative ELISAs showed that Rooibos tea contained significantly lower estrone (E1), estradiol (E2) and estriol (E3) levels than Black tea. The effects of Rooibos and Black tea on proliferation of the estrogen dependant MCF-7 cell line was determined to further characterise the phytoestrogenic properties of the teas. Both Rooibos and Black tea extracts caused a significant inhibition of MCF-7 proliferation. This study shows that Rooibos tea and Black tea are beverages that can either stimulate or suppress the immune system. Also, both teas contain significant levels of phytoestrogens as determined by quantitative ELISAs. The current study confirms previous reports showing inhibition of growth in breast cancer cell lines by phytoestrogens. The findings extend related observations on the anti-carcinogenic potential of the two teas. / South Africa

O chá é uma das bebidas mais consumidas no mundo. Os chás provenientes da planta Camellia sinensis possuem altos teores de antioxidantes, o que significa que podem ter diversos efeitos benéficos na preservação da saúde. Durante séculos, a humanidade procura formas de conservar melhor e por mais tempo os alimentos que consomem. O processo de irradiação de alimentos é uma técnica amplamente utilizada em todo o mundo e é indicada por diversos órgãos de saúde e sanitários de diversos países. A radiação interage com o material causando dois tipos de efeitos, o efeito direto e o efeito indireto. No efeito direto a radiação interage com a molécula de DNA, causando a quebra dessa molécula, inativando a célula. No efeito indireto, que representa 70% da interação, a radiação quebra a molécula de água presente no meio, em um processo chamado de radiólise, criando uma série de radicais livres que vão interagir com os componentes celulares, levando a morte da célula. Portanto, o objetivo deste trabalho foi estudar os efeitos da radiação gama em dois tipos de chás da planta Camellia sinensis irradiados com diferentes valores de atividade de água. As amostras de chá verde e chá preto tiveram suas Aw ajustadas a três valores (Aw alta, Aw média e Aw baixa). As amostras foram irradiadas em fonte de 60Co nas doses de 0; 1,0; 1,5; 2,0; 2,5; 5,0; 7,5 e 10,0 kGy. As análises utilizadas foram: microbiologia por semeadura de superfície, quantificação de fenólicos totais, análise da atividade antioxidante por ORAC e identificação e quantificação dos principais antioxidantes presente nessas bebidas. Foi possível constatar que quanto maior a quantidade de água livre presente no meio, menor foi a dose para realizar o controle microbiológico. O chá verde mostrou ser um pouco mais suscetível a irradiação com alta Aw do que o chá preto, pois houve variação da quantidade de fenólicos e flavonóides, diminuindo a quantidade desses compostos em algumas doses, mas também houve aumento da quantidade em outras doses. Entretanto em ambos os chás, essas mudanças podem ser consideradas insignificantes, uma vez que não houve diferença da atividade antioxidante em doses de até 10 kGy. A dose de 5,0 kGy foi a dose mínima que garantiu o controle microbiológico e não causou alterações nos parâmetros analisados. / Tea is the most consumed beverage in the world. Teas from Camellia sinensis plant have high levels of antioxidants, which mean that they may have several beneficial effects on health preservation. For centuries, mankind looks for ways to conserve better and for a longer time the food that they eat. The food irradiation process is a largely technique used worldwide, and is recommended by many health agencies and authorities of several countries. The radiation interacts with the material causing two kinds of effects, the direct and the indirect effect. In the direct effect the radiation interacts with the DNA molecule, breaking it, and then inactivates the cell. In the indirect effect, which represents 70% of the interaction, the radiation breaks the water molecule in a process denominated radiolysis, creating a number of free radicals that will interact with the cellular components, leading to the cell death. Therefore, the aim of this work is to study the effects of gamma radiation on two kinds of tea from Camellia sinensis plant irradiated with different water activities. The green tea and black tea samples had their Aw adjusted to three values (high Aw, medium Aw, and low Aw). The samples were irradiated in 60Co source at doses of 0, 1.0, 1.5, 2.0, 2.5, 5.0, 7.5, and 10.0 kGy. The analyses used were: microbiology by plate count, total phenolic compounds quantification, antioxidant activity by ORAC assay, and identification and quantification of main antioxidants in these beverages. It was noted that the greater the quantity of free water present in the medium, the lower was the dose to achieve microbiological control. The green tea showed to be a little more susceptible to irradiation by high Aw once there was more variation in the amount of flavonoids and phenolics than the black tea, decreasing the amount of these compounds in some doses, but increasing the amount in other ones. However in both teas, these changes can be considered insignificant, since there was no difference in antioxidant activity at doses up to 10 kGy. The dose of 5.0 kGy was the minimum dose that secured the microbiological control and had no changes on the parameters analyzed.

O chá é uma das bebidas mais consumidas no mundo. Os chás provenientes da planta Camellia sinensis possuem altos teores de antioxidantes, o que significa que podem ter diversos efeitos benéficos na preservação da saúde. Durante séculos, a humanidade procura formas de conservar melhor e por mais tempo os alimentos que consomem. O processo de irradiação de alimentos é uma técnica amplamente utilizada em todo o mundo e é indicada por diversos órgãos de saúde e sanitários de diversos países. A radiação interage com o material causando dois tipos de efeitos, o efeito direto e o efeito indireto. No efeito direto a radiação interage com a molécula de DNA, causando a quebra dessa molécula, inativando a célula. No efeito indireto, que representa 70% da interação, a radiação quebra a molécula de água presente no meio, em um processo chamado de radiólise, criando uma série de radicais livres que vão interagir com os componentes celulares, levando a morte da célula. Portanto, o objetivo deste trabalho foi estudar os efeitos da radiação gama em dois tipos de chás da planta Camellia sinensis irradiados com diferentes valores de atividade de água. As amostras de chá verde e chá preto tiveram suas Aw ajustadas a três valores (Aw alta, Aw média e Aw baixa). As amostras foram irradiadas em fonte de 60Co nas doses de 0; 1,0; 1,5; 2,0; 2,5; 5,0; 7,5 e 10,0 kGy. As análises utilizadas foram: microbiologia por semeadura de superfície, quantificação de fenólicos totais, análise da atividade antioxidante por ORAC e identificação e quantificação dos principais antioxidantes presente nessas bebidas. Foi possível constatar que quanto maior a quantidade de água livre presente no meio, menor foi a dose para realizar o controle microbiológico. O chá verde mostrou ser um pouco mais suscetível a irradiação com alta Aw do que o chá preto, pois houve variação da quantidade de fenólicos e flavonóides, diminuindo a quantidade desses compostos em algumas doses, mas também houve aumento da quantidade em outras doses. Entretanto em ambos os chás, essas mudanças podem ser consideradas insignificantes, uma vez que não houve diferença da atividade antioxidante em doses de até 10 kGy. A dose de 5,0 kGy foi a dose mínima que garantiu o controle microbiológico e não causou alterações nos parâmetros analisados. / Tea is the most consumed beverage in the world. Teas from Camellia sinensis plant have high levels of antioxidants, which mean that they may have several beneficial effects on health preservation. For centuries, mankind looks for ways to conserve better and for a longer time the food that they eat. The food irradiation process is a largely technique used worldwide, and is recommended by many health agencies and authorities of several countries. The radiation interacts with the material causing two kinds of effects, the direct and the indirect effect. In the direct effect the radiation interacts with the DNA molecule, breaking it, and then inactivates the cell. In the indirect effect, which represents 70% of the interaction, the radiation breaks the water molecule in a process denominated radiolysis, creating a number of free radicals that will interact with the cellular components, leading to the cell death. Therefore, the aim of this work is to study the effects of gamma radiation on two kinds of tea from Camellia sinensis plant irradiated with different water activities. The green tea and black tea samples had their Aw adjusted to three values (high Aw, medium Aw, and low Aw). The samples were irradiated in 60Co source at doses of 0, 1.0, 1.5, 2.0, 2.5, 5.0, 7.5, and 10.0 kGy. The analyses used were: microbiology by plate count, total phenolic compounds quantification, antioxidant activity by ORAC assay, and identification and quantification of main antioxidants in these beverages. It was noted that the greater the quantity of free water present in the medium, the lower was the dose to achieve microbiological control. The green tea showed to be a little more susceptible to irradiation by high Aw once there was more variation in the amount of flavonoids and phenolics than the black tea, decreasing the amount of these compounds in some doses, but increasing the amount in other ones. However in both teas, these changes can be considered insignificant, since there was no difference in antioxidant activity at doses up to 10 kGy. The dose of 5.0 kGy was the minimum dose that secured the microbiological control and had no changes on the parameters analyzed.