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.

Les pyranoanthocyanes sont des pigments présents dans les vins rouges qui évoluent considérablement pendant la vinification et l’élevage. Ils contribuent à la stabilité de la couleur au cours du vieillissement. Ce sont aussi de bons marqueurs de l’oxydation d’un vin rouge. Cependant, leur impact sensoriel est encore mal connu. L’objectif de cette thèse est de mettre en évidence un possible impact gustatif des pyranoanthocyanes. Pour répondre à cette problématique, une stratégie de caractérisation, de purification et de quantification a été élaborée. La chromatographie de partage centrifuge (CPC) a été utilisée comme technique chromatographique principale pour fractionner des échantillons de vin rouge micro-oxygénés. Huit fractions de composition différente ont été collectées. La première fraction est composée essentiellement de pigments coumaroylés, la seconde fraction principalement de flavanol-pyranoanthocyanes. Les pigments de ces deux fractions ont été purifiés par CLHP préparative puis semi-préparative. L’analyse de la structure par résonnance magnétique nucléaire a permis la caractérisation de quatre nouveaux pigments. La quantification des différentes familles de pigments dans des vins micro-oxygénés ou avec des modalités variables de dioxyde de soufre a été réalisée par UCLHP-DAD-ESI-QToF. Les résultats ont montré une évolution de la contribution des familles de pigments en corrélation avec l’oxygène. En particulier, la corrélation de la concentration en hydroxyphényl-pyranoanthocyanes avec l’oxygène et le SO2 a été pour la première fois mise en évidence. Les quatre nouveaux pigments ont été quantifiés dans tous les vins étudiés. Ils ont montré le même schéma d’évolution que leurs familles de pigments respectives. Ce sont donc de bons marqueurs de l’oxydation d’un vin rouge. Les pigments des deux premières fractions issues de la CPC ont été solubilisés dans une solution modèle de vin et utilisés pour l’analyse sensorielle. La fraction 1 ne nous a pas permis de conclure quant à un possible impact sensoriel. Un test triangulaire construit autour de six concentrations croissantes a été mis en place pour la caractérisation de la fraction 2. Les dégustateurs ont perçu un impact sensoriel en bouche et décrivent de l’amertume et une sensation de rondeur. C’est un premier résultat significatif en faveur de la compréhension et de l’amélioration de la connaissance de l’impact gustatif des pyranoanthocyanes dans les vins rouges. / Pyranoanthocyanins are pigments occurring in red wines. They considerably evolve during winemaking and aging. They contribute to wine color stability during aging. They are also great markers of oxidation. However, data about their sensory impact are still scarce. In order to answer this dilemma, characterization, purification and quantification strategies have been developed. Centrifugal partition chromatography (CPC) has been used as the main chromatographic technique for micro-oxygenated red wine fractionation. Eight fractions with variable composition have been collected. The first fraction is mainly composed of coumaroylated pigments, and the second fraction mainly composed of pyranoanthocyanins-flavanols. Pigments from these fractions have been purified using preparative and semi-preparative HPLC. Nuclear magnetic resonance for structural analysis allowed characterizing four new pigments. The concentration of several groups of pigments has been evaluated in micro-oxygenated red wines of red wines with variable modalities of Sulphur dioxide, using UPLC-DAD-ESI-QToF. The results showed a correlation between the contribution of pigments and oxygen. More specifically, the correlation between the concentration in hydroxyphenyl-pyranoanthocyanins and oxygen and Sulphur dioxide has been highlighted for the first time. The four new pigments have been quantified in all wine samples. They showed the same trend than their respective groups of pigments. They can therefore be considered as good markers of oxidation.Pigments from the two first CPC fractions have been solubilized in a wine-like medium and used for sensory analysis. Fraction 1 did not allow concluding a possible sensory impact. A triangle test has been built using six increasing concentrations to evaluate the impact of fraction 2. The wine-tasters have perceived in-mouth impact and described bitterness and roundness. This is a very first significant result in favor of understanding and improving knowledge about gustative impact of pyranoanthocyanins in red wines.

Worldwide, millets are regarded as significant grains; however, they are the least exploited. Millet grain is abundant in nutrients and health-beneficial phenolic compounds, making it suitable as food and feed. The diverse contents of nutrients and phenolic compounds present in finger and pearl millet are good indicators that the variety of millet available is important when selecting it for use as food or feed. The phenolic properties found in millets comprise of phenolic acids, flavonoids, and tannins, which are beneficial to human health. Research has shown that millet phenolic properties have high antioxidant activity. Phytochemicals present in millet grains have positive effects on human health by lowering the cholesterol and phytates in the body. The frantic demands on maize and its uses in multiple industries have merit the search for alternative grains, to ease the pressure. Substitution of maize with pearl and finger millets in the diets of different animals resulted in positive impact on the performance. Of late, millet grain has been incorporated in other foods and used to make traditional beverages. In Chapter 1, the topic of the research was introduced, stating the importance of the study and to motivate on the significance of millet grains. Aims and objectives were also listed. Chapter 2 presented extensive literature review on millet and their uses in human and livestock nutrition. In addition, the use of tannin as alternative feed was also reviewed. Different studies have been conducted to investigate the suitability of millet grain as an energy source, in the animal industry. However, studies on the Southern African types of millet are limited; this might be due to lack of information on their nutritional composition and their suitability as animal feed. Overall, the aim of this study was to profile the nutritional characteristics of selected millet grains in South Africa and Zimbabwe, their suitability as energy source for human and livestock and to study the effect of pearl millet type on the performance indices of Ross 308 broiler chickens. In Chapter 3, the general materials and methods used to reach the scientific conclusion for this study was summarised. In Chapter 4, physical and chemical analysis were conducted on millet grains obtained from South Africa and Zimbabwe, the results revealed that the physiochemical characteristics of the millet grain qualify it as a suitable candidate in replacing maize as an energy source. To further understand the characteristics of the millet grain, Chapter 5 analysed the phenolic compounds available in the millet grain obtained from South Africa and Zimbabwe. The results showed that the grain is endued with valuable phenolic compounds beneficial in the nutrition of both human and animals and aid as health benefit. Chapter 6 investigated the various inclusion levels of pearl millet in a bid to establish the most suitable combination for the poultry sector. Pearl millet grain used in this experiment went through different breeding improvements and selections conducted at the Grain Crop Institute in Potchefstroom, South Africa. Pearl millet grain was used as the main source of energy for Ross 308 broiler chicks for a period of 42 days with performance indices investigated. The results revealed that pearl millet can be incorporated in the diets of broiler chickens, in replacement of maize, without adversely affecting the performance. In addition, the economic justification of replacing maize with pearl millet was studied. The cost of the grains was determined and the cost per weight gain was determined. The results showed that indeed it is economically sound to replace maize with pearl millet in the diet of poultry. The quadratic function best fitting optimum treatment combination in relation to performance parameters such as body weight, body weight gain, feed conversion ratio and internal organs was also examined. In Chapter 7, the research was generally discussed to tie up the conclusions of the experiments conducted. General recommendations were also given on the compounds of millet varieties and their health benefits to both humans and animals. / Kuwo wonke umhlaba, amabele athathwa njengezinhlamvu ezibalulekile, kodwa awasetshenziswa kakhulu. Uhlamvu lwebele lunemisoco eminingi kanye nenzuzo yempilo ngama-phenolic compound, okwenza ukuthi afaneleke kakhulu njengokudla kwabantu kanye nemfuyo. Imisoco eminingi equkethwe kanye nama-phenolic compound atholakala eminweni kanye nezinhlamvu zebele ayizinkomba ezinhle zokuthi izinhlobo zamabele ezitholakalayo zibaluleke kakhulu ekukhethweni njengokudla kanye nokudla kwabantu noma imfuyo. Amaphenolic properties atholakala kumabele aqukethe ama-phenolic acids, ama-flavonids, kanye nama-tannins, ayinzuzo kakhulu empilweni yabantu. Ucwaningo luthole ukuthi ama-phenolic properties amabele anomsebenzi wezinga eliphezulu lama-antioxidant. Ama-phytochemicals atholakala kwizinhlamvu zamabele anenzuzu enhle kakhulu kwimpilo yabantu ngokwehlisa izinga le-cholesterol kanye nama-phytate emzimbeni. Ukudingeka kakhulu kombila kanye nokusetshenziswa kwawo kwizimboni eziningi, kubangele ukuthi kwenziwe ucwaningo ngezinye izinhlamvu ukwehlisa ingcindezi. Ukuthatha isikhundla sombila, sithathwa amabele kwidayethi yezilwane ezehlukene kwaba nomphumela omuhle kakhulu ngokusebenza. Kamuva nje, izinhlamvu zamabele zifakelwe kwezinye izidlo ezisetshenziswa ukwenza iziphuzo zomdabu. Kwisahluko 1, isihloko socwaningo sethulwa khona, ukuchaza ukubaluleka kocwaningo kanye nokuqikelela ngokubaluleka kwezinhlamvu zamabele. Izinhloso nezinjongo nazo zifakelwe kuhla. Isahluko 2, sethula ukubuyekezwa kwemibhalo ngamabele kanye nokusetshenziswa kwawo kubantu kanye nokudla kwemfuyo. Nangaphezu kwalokho, ukusetshenziswa kwe-tannin njengokunye ukudla kwemfuyo kuye kwabuyekezwa. Kwenziwe ucwaningo olwehlukene ukuphenyisisa ngokufaneleka kwezinhlamvu zamabele njengomthombo wamandla (we-eneji) kwimboni yezilwane. Kodwa, ucwaningo ngezinhlobo zamabele eNingizimu ne-Afrika alukenziwa ngokwanele; lokhu kungenzeka kungenxa yokuswelakala kolwazi ngemisoco equkethwe kanye nokufaneleka njengokudla kwezilwane. Kanti ngokwengamele, inhloso yalolu cwaningo bekuwukwenza iprofayili yemisoco ngezinhlamvu zamabele athile eNingizimu Afrika kanye naseZimbabwe, ukufaneleka kwawo njengomthombo wamandla (we-eneji) kubantu kanye nemfuyo, kanye nokwenza ucwaningo ngemiphumela yenhlobo yamabele ngama-performance indices wamachwane e-ROss 308. Kwisahluko 3, kusetshenziswe imetheriyali kanye namamethodi asetshenzisiwe ukufinyelela isiphetho sezesayense kulolu cwaningo, kwafinyezwa. Kwisahluko 4 kwenziwe uhlaziyo lokubambekayo kanye namakhemikhali ngezinhlamvu zamabele ngokutholakale eNingizimu Afrika kanye naseZimbabwe, imiphumela ikhombise ukugqama kwe-physiochemical kwezinhlamvu zamabele ukufaneleka kwazo njengekhandideti ekuthatheni isikhundla sombila njengomthombo wamandla. Ukuqhubeka nokuqondisisa ukuphawuleka kwezinhlamvu zamabele, iSahluko 5 sihlaziye ama-phenolic compound kwizinhlamvu zamabele aseNingizimu Afrika neZimbabwe. Imiphumela ikhombisa ukuthi uhlamvu lwamabele lunama-phenolic compound ayinzuzo ekudleni okunomsoco kubantu kanye nezilwane, kanye nokuba wusizo lwenzuzo kwimpilo. Isahluko 6 siphenyisise ngamazinga okubandakanywa kwamabele ukwenzela ukuthola ukufaneleka kwawo kumkhakha wezinkukhu. Izinhlamvu zamabele e-pearl zisetshenziswe kule ekspirimenti, eyenziwa ezigabeni ezehlukene zokuthuthukisa ukuzalisa kanye nokhetho olwenziwe ngabe-Grain Crop Institute ePotchefstroom, eNingizimu Afrika. Amabele e-pearl asetshenziswe njengomthombo omkhulu we-eneji kumachwane eRoss 308 isikhathi sezinsuku ezingu 42 kanti kwaphenyisiswa ngokusebenza kwama-indices. Imiphumela iveze ukuthi amabele epearl angafakelwa kwidayethi yamachwane, ukuthatha isikhundla sombila, ngaphandle kokuphazamisa ukusebenza. Nangaphezu kwalokho, ukufaneleka kwezomnotho ngokuthatha isikhundla zombila sithathwa ngamabele e-pearl kuye kwacwaningwa. Izindleko zezinhlamvu ziye zabekwa kanti futhi nesisindo ngezinhlamvu kuye kwabekwa. Imiphumela ikhombisa ukuthi kuyinto enhle kwezomnotho ukuthatha isikhundla sombila sithathwa ngamabele e-pearl kwidayethi yezinkukhu. Ukusebenza kwe-quadratic function kufaneleke kakhulu kwi-optimum treatment combination mayelana nama-parameter okusebenza afana nokwenyuka kwesisindo somzimba, ukuguqula i-feed conversion ratio kanye nezitho zangaphakathi nazo ziye zahlolwa. KwiSahluko 7, ucwaningo kuye kwaxoxwa ngalo ukuhlanganisa iziphetho zama-ekspirimenti enziwe. Izincomo ezinabile, ziye zanikezwa ngama-compound ezinhlobo zamabele kanye nezinzuzo zawo kwezempilo kubantu kanye nezilwane / Lefaseng ka bophara, leotša le bonwa bjalo ka mabele a bohlokwa kudu; le ge go le bjale, ke dibjalo tšeo di sa bjalwego kudu. Dithoro tša leotša di tletše ka phepo ye ntši le ditswaki tša fenoliki tšeo di nago le mohola maphelong, gomme se sa dira gore di be maleba bjalo ka dijo le phepo. Dikagare tša lona tšeo di fapafapanego le ditswaki tša fenoliki tšeo di whetšagalago ka gare ga leotša la finger le la pearl ke dilaetši tše kaone tša gore mehutahuta ya leotša yeo e hwetšagalago e bohlokwa ge e kgethwa bjalo ka sejo le phepo. Diteng tša fenoliki tšeo di hwetšwago ka agre ga leotša di na le diesiti tša fenoliki, difolabanoite, le dithaninse, tšeo di lego mohola go maphelo a batho. Dinyakišišo di laeditše gore diteng tša fenoliki tša leotša di na le mošomo wa godimo wa dihlwekišammele tšeo di bitšwago dianthioksitente. Difaethokhemikhale tšeo di lego gona ka gare ga dithoro tša leotša di na le diabe tše kaone go maphelo a batho ka go fokotša kholesterole le difaetheite mmeleng. Dinyakwa tša ka pela go lefela le mešomo ya lona ka diintastering tše ntši di dirile gore go be le nyakego ye kgolo ya dithoro tše dingwe tšeo di ka emelago lefela legato, go nolofatša kgatelelo yeo e beilwego go lefela. Go tšeela lefela legato ka leotša la pearl le la finger ka dijong tša diphoofolo tšeo di fapafapanego go feleleditše ka seabe se sekaone ka ga go šoma ga lona. Go fihla mo lebakeng le, dithoro tša leotša di tsentšwe ka dijong tše dingwe gomme tša šomišwa go dira dino tša setšo. Ka go Kgaolo ya 1, hlogotaba ya dinyakišišo e tsebagaditšwe, ya fa bohlokwa bja dinyakišišo tše le lebaka mabapi le bohlokwa bja dithoro tša leotša. Maike mišetšo le dinepo le tšona di filwe. Kgaolo ya 2 e hlagišitše tekodišišo ya dingwalwa ye e tseneletšego ka ga leotša le mešomo ya lona go phepo ya batho le ya diphoofolo. Godimo ga fao, tšhomišo ya tannin bjalo ka phepo ya boikgethelo le yona e lekodišišitšwe. Dinyakišišo tše di fapafapanego di dirilwe go nyakišiša go ba maleba ga thoro ya leotša bjalo ka methopo wa enetši, ka intastering ya diphoofolo. Le ge go le bjale, dinyakišišo tš0e di dirilwego mabapi le mehuta ya leotša ka Borwa bja Afrika ke tše nnyane; se se ka ba se bakwa ke tlhoklego ya Tshedimošo mabapi le sebiopego sa phepo ka hare ha leotša le go ba maleba ga lona bjalo ka phepo ya diphoofolo. Ka kakaretšo, maikemišetšo a dinyakišišo tše e bile go lebeledišiša dikokwane tša phepo tša dithoro tša leotša tšeo di kgethilwego ka Afrika Borwa le ka Zimbabwe, go ba maleba ga lona bjalo ka methopo wa enetši go batho le go diruiwa le go nyakišiša ka ga seabe ka ga mohuta wa leotša wa pearl go go šoma ga dipalopalo go dikgogo tša nama tša Ross 308. Ka go Kgaolo ya 3, ditlabelo le mekgwa ka kakaretšo yeo e šomišitšwego go fihlelela sephetho sa tša mahlale sa dinyakišišo tše di filwe kakaretšo. Ka go Kgaolo ya 4, tshekatsheko ya naga le ya dikhemikhale e dirilwe mabapi le dithoro tša leotša tšeo di hweditšwego ka Afrika Borwa le ka Zimbabwe, dipoelo di utollotše gore dikagare tša dikhemikhale tša thoro ya leotša di le dira le be lebele leo le loketšego go tšeela legato lefela bjalo ka methopo wa enetši. Go kwešiša go tšwela pele dikagare tša thoro ya leotša, Kgaoilo ya 5 e sekasekile diteng tša fenoliki tšeo di hwetšagalago ka gare ga thoro ya leotša leo le hwetšago ka Afrika Borwa le ka Zimbabwe. Dipoelo di laeditše gore thro ya leotša le tletše ka dikagare tša fenoliki tšeo di lego mohola go phepo ya bobedi batho le diphoofolo le gore le thuša bjalo ka kholego ya tša phepo. Kgaolo ya 6 e nyakišišitše maemo a mehutahuta a kakaretšo a leotša la pearl ka nepo ya go hwetša motswako wa maleba kudu ka lekaleng la dikgogo. Dithoro tša leotša la pearl tšeo di šomišitšwego ka mo tekodišišong ye di sepedišitšwe ka go dikaonafatšo tše di fapanego tša monontšha gomme dikgetho di dirilwe ka go Sehlongwa sa Dibjalo tša Dithoro ka Potchefstroom, ka Afrika Borwa. Dithoro tša leotša la pearl di šomišitšwe bjalo ka mothopo wa enetši go matswiana a nama a Ross 308 mo matšatšing a 42 fao go dirilwego dinyakišišo ka ga dipalopalo tša go gola ga dikgogo. Dipoelo di laeditše gore leotša la pearl le ka tsenywa ka dijong tša dikgogo tša nama, go tšeela legato lefela, ka ntle le go ama gampe go gola ga dikgogo. Godimo ga fao, lebaka la tša ekonomi la go tšeela lefela legato ka leotša la pearl le nyakišišitšwe. Theko ya dithoro e hweditšwe gomme theko ka boima bjo itšego le yona e hweditšwe. Dipoelo di laeditše gore ka nnete go tloga go kwagalago kudu go tša ekonomi go tšeela lefela legato ka leotša la pearl. Mošomo wa tekanelo wa wo o loketšego bokaone motswako wa tlhokomelo ya godimo mabapi le mahlakore a kgodišo ya dikgogo a go swana le boima bja mmele, go nona, rešio ya go fetošetša dijo le ditho tša ka gare le ona o lekodišišitšwe. Ka go Kgaolo ya 7, dinyakišišo di hlalošitšwe ka kakaretšo gore go fihlelelwe sephetho ka ga ditekodišišo tšeo di dirilwego. Ditšhišinyo ka kakaretšo le tšona di filwe mabapi le dikagare tša mehutahuta tša leotša le dikholego tša ona go tša maphelo go bobedi batho le diphoofolo / College of Agriculture and Environmental Sciences / D. Phil. Agr. (Animal Science)

Les travaux présentés dans ce manuscrit ont été consacrés à la compréhension du procédé de fabrication des mousses phénoliques et de la chimie associée, dans le but de proposer des modifications de la formulation permettant l’amélioration de ses propriétés mécaniques (friabilité et comportement en compression). Dans un second temps, les propriétés mécaniques en compression, en flexion et la friabilité ont été caractérisées en fonction de la densité relative de la mousse. Les caractéristiques de compression ont été modélisées et comparées aux modèles de Gibson et Ashby. Les résultats montrent que le module d’Young et la contrainte au plateau de compression sont des fonctions quadratiques de la densité relative. Le comportement thermique de la mousse phénolique a été également étudié. L’évolution de la structure chimique des résidus obtenus après différents traitement thermique a été suivie par IRTF. Les observations spectrales ont été interprétées en fonction des réactions de dégradat ion proposées dans la littérature. Les paramètres cinétiques de dégradation de la mousse phénolique ont été déterminés grâce à différentes méthodes dites « model-free kinetic» développées par Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose et Friedman. Finalement, dans une première approche, nous avons essayé de déterminer les paramètres cinétiques, en condition isotherme, du phénomène d’oxydation qui apparait à faible température / The following work has been devoted to the understanding of the phenolic foam manufacturing process and the associated chemistry, to propose modifications of the formulation itself that allows an enhancement in mechanical properties (friability and compression behavior). In addition, these mechanical properties in compression, bending and brittleness were characterized as a function of the foam relative density. Compression properties were modeled and compared to the Gibson and Ashby models. Results show that Young's modulus and collapse plateau stress are quadratic functions of the relative density. Moreover, the thermal behavior of the phenolic foam was also studied. The evolution of the chemical structure of the obtained residues after different thermal treatment was followed by FTIR. Spectral observations were interpreted according to the degradation reactions proposed in the literature. The kinetic parameters of phenolic foams degradation have been determined using different "mo del-free kinetic" approaches, developed by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Friedman. Finally, in a first approach, we tried to determine the kinetic parameters, in isothermal condition, of the oxidation phenomenon that appears at low temperature

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Prohexadione-calcium (Pro-Ca), a plant growth regulator used primarily in fruit trees to suppress excessive vegetative growth and to inhibit disease incidence, is known to inhibit dioxygenase enzymes and to inhibit GA biosynthesis. It induces genes for polyphenols synthesis. The objective of this project was to determine if the bioregulator Pro-Ca would alter the yield of essential oil, secondary metabolites, and growth in spearmint. Spearmint shoot cuttings from the same mother plant were used in this study. The plants were treated with 0, 125, 250, 375, and 500 mg/L a.i. of Pro-Ca over four weeks, and growth responses were measured every week and at harvest. Compared with the untreated control plants, plant height, branch length, number of nodes, and fresh weight were decreased with increased concentration of Pro-Ca treatment, and total phenolics accumulation increased. Rosmarinic acid and total chlorophyll content were reduced relative to control after treatment. Treatment with increased concentration of Pro-Ca altered the accumulation of flavonoids compounds. Increased concentration of catechin and eriodictyol-7-glucoside, and decreased concentrations of procyanidin and luteolin occurred compared with the untreated plant. Modification of newly formed flavonoid synthesis could be used as a new potential strategy in plant protection.