Na busca por vinhos tintos de grande cor, aroma, corpo e identidade, enólogos forçam a extração dos compostos fenólicos durante a maceração. Nesta etapa, que ocorre durante a fermentação do mosto, estes compostos são extraídos da casca e sementes e modificados em sua estrutura à formas mais estáveis ao longo do tempo. Fatores como sistema de encubagem e remontagem do mosto, tempo de contato entre o mosto e as partes sólidas da baga, e a temperatura são críticos neste processo. A alteração do ciclo da videira para colheita no período de inverno na região sudeste do Brasil permitiu avanço na maturação fenólica das bagas. As uvas colhidas neste período apresentam potencial para a elaboração de vinhos de guarda, entretanto faltam estudos para estabelecer as melhores técnicas de vinificação para este novo ciclo de produção. Este trabalho teve como objetivo avaliar o emprego de baixas temperaturas na extração e estabilidade de antocianinas, taninos e do precursor de aroma acetato de isoamila. Uvas da variedade Syrah colhidas no inverno foram submetidas a vinificação com maceração pré-fermentativa a frio (5 - 8°C) e posterior fermentação alcoólica na presença das cascas a baixa temperatura (15 °C), e também pelo método tradicional (maceração e fermentação alcoólica entre 20 e 23°C). Teores de polifenóis totais, antocianinas, intensidade e tonalidade de cor, compostos fenólicos, flavanóis, índice de pigmentos polimerizados e acetato de isoamila foram avaliados durante a maceração e nas etapas de fermentação malolática, engarrafamento e envelhecimento em garrafa. Os vinhos com 14 meses de envelhecimento foram submetidos a um painel sensorial. O método de maceração tradicional permitiu maior extração de antocianinas e, consequentemente, maior intensidade de cor. Entretanto, o emprego do frio preservou os tons azuis (OD 620%) durante o envelhecimento, o que indica menor oxidação do vinho. A concentração de compostos fenólicos também foi maior na maceração tradicional. O vinho submetido ao frio apresentou maior índice de pigmentos polimerizados e maior preservação de tons vermelhos e compostos fenólicos totais durante o envelhecimento, além de menores teores de acetato de isoamila. Não houve diferença estatística entre os descritores apresentados na análise sensorial; entretanto, a média do parâmetro de preferência global foi maior no método tradicional. Os resultados indicam potencial de preservação dos compostos fenólicos pelo uso do tratamento a frio, entretanto outras técnicas devem ser avaliadas para melhorar a extração desses compostos em uvas colhidas no inverno. / In an attempt to elaborate red wines of great color, aroma, body and identity, winemakers overextract phenolic compounds at maceration. At this step, which occurs during must fermentation, grape solids are extracted from skins and seeds and their structure are modified to more stable forms over time. Factors such as types of maceration, pumping-over, maceration time and temperature are critical in this red winemaking step. The modification of grapevine cycle in the southeastern region of Brazil to harvest grapes in the winter season has improved phenolic ripeness of the berries. Grapes harvested at this period have potential to ageing, however there are few studies to establish the best winemaking techniques for these berries. This study aimed to evaluate the use of low temperature in the extraction and stability of anthocyanins, tannins and flavor precursor isoamyl acetate. Syrah grapes harvested in winter season were processed with pre-fermentative cold maceration (5 - 8 °C) and then allowed to start alcoholic fermentation in the presence of pomace at low temperature (15 °C), and also processed by the conventional method (maceration and alcoholic fermentation between 20 and 23°C). Total polyphenols, anthocyanins, intensity and color hue, phenolic compounds, flavanols, polymerized pigments index and isoamyl acetate were evaluated during maceration, malolactic fermentation, bottling and bottle ageing steps. Wines aged in bottles for 14 months were subjected to a sensory panel. The conventional method allowed more anthocyanins extraction and consequently resulted in wines with more color intensity. However, the use of cold temperatures preserved the blue component (OD 620%) during ageing, which indicates less wine oxidation. The concentration of phenolic compounds was also higher in wines from the conventional method. Cold macerated wines showed higher polymerized pigments index and preservation of the red component of color and total phenolic compounds during ageing, and lower levels of isoamyl acetate. There was no statistical difference among sensory descriptors presented in the sensorial analysis; however, the parameter of overall preference was higher scored for the conventional method. Results showed potential for phenolic compounds stabilization by the use of cold treatment, but other techniques should be evaluated to improve the extraction of these compounds in grapes harvested in winter season.

Na busca por vinhos tintos de grande cor, aroma, corpo e identidade, enólogos forçam a extração dos compostos fenólicos durante a maceração. Nesta etapa, que ocorre durante a fermentação do mosto, estes compostos são extraídos da casca e sementes e modificados em sua estrutura à formas mais estáveis ao longo do tempo. Fatores como sistema de encubagem e remontagem do mosto, tempo de contato entre o mosto e as partes sólidas da baga, e a temperatura são críticos neste processo. A alteração do ciclo da videira para colheita no período de inverno na região sudeste do Brasil permitiu avanço na maturação fenólica das bagas. As uvas colhidas neste período apresentam potencial para a elaboração de vinhos de guarda, entretanto faltam estudos para estabelecer as melhores técnicas de vinificação para este novo ciclo de produção. Este trabalho teve como objetivo avaliar o emprego de baixas temperaturas na extração e estabilidade de antocianinas, taninos e do precursor de aroma acetato de isoamila. Uvas da variedade Syrah colhidas no inverno foram submetidas a vinificação com maceração pré-fermentativa a frio (5 - 8°C) e posterior fermentação alcoólica na presença das cascas a baixa temperatura (15 °C), e também pelo método tradicional (maceração e fermentação alcoólica entre 20 e 23°C). Teores de polifenóis totais, antocianinas, intensidade e tonalidade de cor, compostos fenólicos, flavanóis, índice de pigmentos polimerizados e acetato de isoamila foram avaliados durante a maceração e nas etapas de fermentação malolática, engarrafamento e envelhecimento em garrafa. Os vinhos com 14 meses de envelhecimento foram submetidos a um painel sensorial. O método de maceração tradicional permitiu maior extração de antocianinas e, consequentemente, maior intensidade de cor. Entretanto, o emprego do frio preservou os tons azuis (OD 620%) durante o envelhecimento, o que indica menor oxidação do vinho. A concentração de compostos fenólicos também foi maior na maceração tradicional. O vinho submetido ao frio apresentou maior índice de pigmentos polimerizados e maior preservação de tons vermelhos e compostos fenólicos totais durante o envelhecimento, além de menores teores de acetato de isoamila. Não houve diferença estatística entre os descritores apresentados na análise sensorial; entretanto, a média do parâmetro de preferência global foi maior no método tradicional. Os resultados indicam potencial de preservação dos compostos fenólicos pelo uso do tratamento a frio, entretanto outras técnicas devem ser avaliadas para melhorar a extração desses compostos em uvas colhidas no inverno. / In an attempt to elaborate red wines of great color, aroma, body and identity, winemakers overextract phenolic compounds at maceration. At this step, which occurs during must fermentation, grape solids are extracted from skins and seeds and their structure are modified to more stable forms over time. Factors such as types of maceration, pumping-over, maceration time and temperature are critical in this red winemaking step. The modification of grapevine cycle in the southeastern region of Brazil to harvest grapes in the winter season has improved phenolic ripeness of the berries. Grapes harvested at this period have potential to ageing, however there are few studies to establish the best winemaking techniques for these berries. This study aimed to evaluate the use of low temperature in the extraction and stability of anthocyanins, tannins and flavor precursor isoamyl acetate. Syrah grapes harvested in winter season were processed with pre-fermentative cold maceration (5 - 8 °C) and then allowed to start alcoholic fermentation in the presence of pomace at low temperature (15 °C), and also processed by the conventional method (maceration and alcoholic fermentation between 20 and 23°C). Total polyphenols, anthocyanins, intensity and color hue, phenolic compounds, flavanols, polymerized pigments index and isoamyl acetate were evaluated during maceration, malolactic fermentation, bottling and bottle ageing steps. Wines aged in bottles for 14 months were subjected to a sensory panel. The conventional method allowed more anthocyanins extraction and consequently resulted in wines with more color intensity. However, the use of cold temperatures preserved the blue component (OD 620%) during ageing, which indicates less wine oxidation. The concentration of phenolic compounds was also higher in wines from the conventional method. Cold macerated wines showed higher polymerized pigments index and preservation of the red component of color and total phenolic compounds during ageing, and lower levels of isoamyl acetate. There was no statistical difference among sensory descriptors presented in the sensorial analysis; however, the parameter of overall preference was higher scored for the conventional method. Results showed potential for phenolic compounds stabilization by the use of cold treatment, but other techniques should be evaluated to improve the extraction of these compounds in grapes harvested in winter season.

Protea cynaroides L. (King Protea) is a well known cutflower. Seeds and stem cuttings are commonly used to propagate P. cynaroides. However, the success rate and rooting rate of seeds and cuttings, are inconsistent and slow. The potential of in vitro propagation as an alternative method to produce P. cynaroides plantlets was investigated. In vitro studies consisted of in vitro germination of mature zygotic embryos, micrografting and direct somatic embryogenesis of zygotic embryos and excised cotyledons. In the germination study, temperature was the most important factor in obtaining a high germination percentage. Alternating temperatures of 21±2ºC/12±2ºC (light/dark) was suitable for germination and over 90% of embryos germinated, while the germination percentage of embryos at 25±2ºC was poor. Plantlets were successfully established in ex vitro conditions when planted in a peat/coir/sand mixture. Micrografting of P. cynaroides was done by grafting microshoots (microscion), which was taken from in-vitro-established nodal explants, onto roots of decapitated in-vitro-germinated seedlings. After the graft union formed, buds on the microscion sprouted. A protocol to induce direct somatic embryogenesis was developed. Direct somatic embryogenesis was achieved on both P. cynaroides mature zygotic embryos and excised cotyledons. The addition of auxins such as NAA and 2,4-D singly or in combination with TDZ, BAP or kinetin suppressed the formation of somatic embryos. Formation of somatic embryos was observed in medium lacking growth regulators. Germination of somatic embryos was highest in medium containing GA3. The roles of starch and phenolic compounds in the rooting of P. cynaroides cuttings were also studied. Starch and total soluble phenol analyses results revealed a positive correlation between high root formation and increased starch and phenolic content. NMR and MS analyses identified high amounts of 3,4-dihydroxybenzoic acid in stems of P. cynaroides. In vitro bioassay showed that 3,4-dihydroxybenzoic acid stimulated and inhibited root growth of P. cynaroides explants, depending on the concentration. A link was made between the endogenous concentration levels of 3,4-dihydroxybenzoic acid and rooting of P. cynaroides stem cuttings. Findings of this study contribute towards a better understanding of the roles starch and phenolic compounds play in the rooting of P. cynaroides. / Thesis (PhD (Horticulture))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

This master thesis deals with the investigation of selected chemical and sensory characteristics of ciders, which were made from four selected apple varieties. The theoretical part describes the chemical composition of apples, cider, the technology of production and production in the world. The next section describes the analytical methods used to determine chemical characteristics not only in ciders but also in other alcoholic beverages. The experimental part focuses on the determination of chemical characteristics such as the content of organic acids, carbohydrates, total phenolic content, alcohol antioxidant activity and elemental composition. The purpose of the work was to find out how different varieties differ in chemical composition. The produced ciders were subjected to sensory analysis to evaluate the selected cider sensory parameters, which were in the natural state and with the addition of carbon dioxide. The results show that ciders of different varieties differ in chemical composition. Malic acid was the most cider's abundant of the organic acids in the range of 2759 – 4411 mg·l-1. Another acid represented was lactic acid in the range of 166,2 – 288,1 mg·l-1. The glucose content of each cider was determined between 845,3 – 1159,8 mg·l-1and fructose 32,6 – 406,7 mg·l-1. Potassium 944,29 – 1073,98 mg·l-1 was the most represented of all elements. The total phenolic content was determined to be in the range of 164,2 – 214,1 mg of GAE·l-1and the antioxidant activity of 0,192 – 0,318 mg·l-1. These differences in chemical composition were also reflected in sensory evaluation. According to the overall assessment, the best cider was made from the Granny Smith variety, which contained the most organic acids and carbohydrates. It has been found that by adding carbon dioxide, sensory parameters such as colour, taste and smell are altered.

Presented diploma thesis was focused on study of phenolic substances in various cereal products. Flours, brans and germs from various cereals, flakes and extruded cereals were chosen as samples. Phenolic substances were analyzed by spectrophotometry, RP-HPLC/UV-VIS and RP-HPLC/PDA/ESI-MS. Studies of saccharide content which were analyzed by spectrophotometry and HPLC/RI was incorporated to this thesis. Differences in the content of phenolic substances released from glycosides after acid hydrolysis of samples and differences in saccharide content determined after acid and enzymatic hydrolysis of samples were investigated. Simple sensory analysis of extruded cereal products of different flavour (cocoa, honey, chocolate) was carried out too. In analyzed samples the highest content of total phenolics and total flavonoids was measured in wheat germs. Especially in wheat germs and also in buckwheat and oat flakes, maize brans and cereals products Teddy (cereal balls with cocoa) and Ferda (cereal grains with honey) high levels of individual catechins, phenolic acids and flavonoids were determined too. The quantity of phenolic substances increased for several times in samples processed by acid hydrolysis in comparison to non-hydrolyzed samples. The high content of total saccharides, reduced saccharides and individual mono- and disaccharides was found mainly in extruded products. Concentration of monosaccharides increased in acid hydrolyzed samples in spite of disaccharides concentration that was higher only in some of hydrolyzed samples. In several cases final disaccharide concentrations were lower in hydrolyzed samples than in non-hydrolyzed ones.

Presented diploma thesis is focused on analysis of selected biologically active substances in different kinds of natural and peeled rice. In rice samples phenolic compounds, antioxidant activity, content of saccharides and vitamin C were analysed. Active substances and saccharides were analysed by UV-VIS spectrophotometry and RP-HPLC-UV/VIS. Content of phenolic compounds and saccharides was measured before and after acid hydrolysis. The content of these compounds increased several times because of release of active substances from glycosides. As a part of diploma thesis basic sensory analysis was performed and consumer questionnaires were evaluated. The highest level of antioxidant activity was detected in Indian Wild rice. The highest content of total polyphenols and flavonoids was detected in Red Rice Natural before acid hydrolysis. After acid hydrolysis the highest content was detected in Indian Wild rice. The highest content of individual flavonoids, phenolic acids and catechins was detected in natural rice Indian Wild, Rice Three colours and in two samples of rice parboiled. The highest content of total and reducing saccharides was found in rice Indian Wild before hydrolysis, while after hydrolysis the content was very similar in all rice samples. The amount of individual monosaccharides after acid hydrolysis increased, while total content of disaccharides decreased. The highest value of simple sugars was detected in rice parboiled and Indian Wild rice. The content of vitamin C was detected only in four rice kinds - in two samples of rice parboiled, Rice Three colours and rice Indian Wild.

Present diploma thesis describes the study of bioactive compounds in the cereals. The work is focused on possible fortification of cereal products in order to increase nutritional value of final products which is reduced during the food processing and storage. Cereal grains are rich in several phenolic compounds, vitamins and minerals that reduce the risk of chronic diseases. The aim of this study was the preparation and analysis of model fortified cereals using lyophilized fruit originating from Czech Republic. A comparative analysis of content of bioactive substances in commercial and fortified products for children was performed too. The experimental part deals with a content of individual flavonoids by RP-HPLC/UV/VIS method, spectrophotometric determination of total and reducing saccharides and analysis of mono- and disaccharides by the HPLC/RI method as well. Differences in the content of individual flavonoids and saccharides after the application of acid hydrolysis of samples were investigated. The content of these compounds increased in most products because of their release from glycosidic forms. Presence of phenolics was confirmed in all analyzed cereals. Addition of 10% of lyophilized fruit/vegetable preparative (carrot, berries, apples) caused several fold increase of phenolics content in model mixtures. In commercially available cereal products there are relatively high differences in total phenolics content, proportionally to fruit component amount. The work included the spectrophotometric analysis of total polyphenols and flavonoids in a model physiological environment (artificial stomach juice) in which the hydrolysis of bound phenolic compounds occurred. The results of this study show that addition of lyophilized fruit seems to be a good way to increase the nutritional value and maintain the content of bioactive compounds in cereal products.

The work deals with the chemical analysis of juices selected varieties of black currant (Ribes nigrum L.). The theoretical part is divided into three main chapters. In the first chapter there are short botanical characteristics of black currants, content of biologically active substances in fruit and utilization of black currant fruit in food industry. In the second chapter there are characteristics, importance and methods of determination of phenolic compounds. Vitamin C is describe in the last chapter, its characteristics, importance and methods of determination. Experimental part describes determination of three chemical characteristic of black currant fruits: content of total phenolic compounds, content of total anthocyanins and content of vitamin C. Twelve modern varieties of black currant were selected for determination. Based on these results, it is possible to deduce the more important varieties. The content of total phenolic compounds was in the range of 326,7–641,4 mg•100 g-1 in all samples. The content of total anthocyanins was analysed in the range from 102,5 to 284,5 mg•100 g-1 in all samples. And content of vitamin C was in the range from 82,0 to 379,1 mg•100 g-1 in all samples. The overall comparison of the varieties of black currant was found, the varieties Ceres, Ben Hope, Ben Lomond, Démon and Ometa are the most promising varieties in terms of the content of the above mentioned compounds.

Plants are an important source of secondary metabolites, such as substances that have a beneficial biological effect on the health of humans and they are irreplaceable in the modern medicine. They may operate in prevention and in the treatment of civilization diseases. In terms of content substances, the phenolic come to fore, especially polyphenols, which have been related to a number of overview studies due to their wide distribution and high concentration in plants. They also represent an important part of substances with redox effects present in the human diet and have an important role for the plant itself. Currently, many laboratories are dedicated to pharmaceutical and biological testing of plants. Individual polyphenols in plant matrices are determined primarily by chromatography, electrophoresis methods, mass spectrometry and nuclear magnetic resonance. Valuable information on the content of polyphenols in plant extract can be obtained also by using spectrophotometric methods. The subject of this thesis is to provide information, characterization and comparison of conventional and modern techniques for the determination of natural substances – phenolic compounds using spectral techniques.

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