The base-catalysed reaction of 4H-pyran-4-one with a range of nucleophiles, namely diethyl malonate, ethyl acetoacetate, nitromethane, acetylacetone and ethyl cyanoacetate, was developed as a reliable, high yielding method for the preparation of para-substituted phenols. The methodology was extended to include the use of the substituted pyranones, maltol, 2,6-dimethyl-4H-pyran-4-one and diethyl chelidonate. Reactions were studied using conventional heating methods and microwave irradiation. Microwave irradiation had definite beneficial effects, with improved yields, reduced reaction times and cleaner reaction profiles. The potential of this methodology was examined for the regioselective placement of ¹³C-atoms into benzene rings using ¹³C-labelled nucleophiles or ¹³C-labelled 4H-pyran-4-ones. [3,5-13C₂]4H-Pyran-4-one and [2,6-13C₂]4H-pyran-4-one were prepared from various ¹³C-labelled versions of triethyl orthoformate and acetone. This methodology was applied to the synthesis of [1,3,5-¹³C₃]gallic acid, via the base-catalysed reaction of [3,5-¹³C₂]4H-pyran-4-one with diethyl [2-¹³C]malonate, followed by subsequent transformations to yield [1,3,5-¹³C₃]gallic acid. The preparation of [2-¹³C]phloroglucinol was carried out via [2-¹³C]resorcinol, with regioselective placement of a single ¹³C-atom into the aromatic ring. This was accomplished from non-aromatic precursors, with the source of the ¹³C-atom being [¹³C]methyl iodide. The key step in this synthesis was the introduction of the third hydroxyl group, which was achieved using a modified iridium-catalysed C-H activation/borylation/oxidation procedure. The scope of an existing C-H activation/borylation reaction was modified and expanded to include a range of protected resorcinol derivatives. A catalyst system was developed which allowed high conversion to the intermediate arylboronic acids, followed by oxidation using aqueous Oxone® to yield the corresponding phenols. Finally, to demonstrate the potential of these new methods for application in the synthesis of isotopically labelled natural products and polyphenols, the syntheses of ¹³C-labelled anthocyanins were studied. A route was developed that could be applied to the synthesis of either cyanidin-3-glucoside or delphinidin-3-glucoside. Only the final coupling/cyclisation step to yield the desired anthocyanin targets remains to be carried out.

Dissertation (PhD(Eng))--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: Coal pyrolysis liquors are a major source of phenolic compounds. The separation of the phenolic compounds from the neutral oils and nitrogen bases also present in the pyrolysis liquors is difficult due to low relative volatilities and the formation of azeotropes. The desired phenolic recovery and phenolic product purity of 99.5 % can therefore not be achieved by means of conventional separation processes. Alternative processes such as liquid-liquid extraction with various low-boiling solvents, mixtures of high-boiling solvents and extractive distillation have been investigated. Disadvantages of these processes include the high solvent ratios required, low recovery of the higher substituted phenolic compounds, inability to treat a wide-boiling feedstock in one process step and complex post-purification of the phenolic product. A solvent system consisting of a selective solvent, water as a co-solvent, and hexane as a countersolvent, is proposed. An industrial heavy naphtha stream was analysed and the most prevalent phenolic compounds, neutral oils and nitrogen bases identified. Three synthetic feed streams were compiled to represent the industrial stream, namely: 1. phenol + benzonitrile + aniline + mesitylene + 5-et-2-me-pyridine 2. m-cresol + o-tolunitrile + o-toluidine + pseudocumene + undecane + indene 3. 2,4-xylenol + 3,5-xylenol + 3,4-xylenol + indane + dodecane + naphthalene The stream containing phenol was used as a basis for solvent selection, with emphasis on the separation of phenol from benzonitrile. A variety of molecules containing hydroxyl and ether functional groups were identified as potential solvents by means of computer-aided molecular design using a genetic algorithm. Of the commercially available solvents tested on batch extraction scale, triethylene glycol achieved the highest phenol-benzonitrile, phenol-aniline and phenol-5-et-2-me-pyridine separation factors as well as the highest phenol recovery. It was concluded from the solvent selection process that effective solvents for the problem under investigation were those containing hydroxyl groups positioned on the molecule backbone in such a way as to facilitate hydrogen bonding with more than one phenolic molecule at a time. Two commercially unavailable solvents, 1,3-(ethoxy-2- hydroxy)-propane-2-01 and 1,3-(diethoxy-4-hydroxy)-propane-2-01 were therefore synthesised from ethylene glycol and diethylene glycol respectively. The molecular structures of these two solvents are analogous to that of triethylene glycol, and contain an additional hydroxyl group. The performance of the synthesised solvents was evaluated and compared to that of triethylene glycol on the basis of m-cresol-otolunitrile, 2,4-xylenol - o-tolunitrile, and 2,4-xylenol - o-toluidine separation factors and phenolic recoveries achieved by means of batch extraction tests. 1,3-(Diethoxy-4- hydroxy)-propane-2-01 yielded higher phenolic recoveries, but lower separation factors than did triethylene glycol. Triethylene glycol was therefore selected for further process development as it is commercially available. A series of batch extractions were carried out on each of the synthetic feed streams using the proposed solvent system. For phenol and m-cresol, recoveries in excess of 99% were obtained in a single stage. Recoveries in excess of 98% were obtained for the xylenol isomers. It was found that the recoveries of the xylenol isomers were more sensitive to changes in the solvent ratios. The separation of phenolic compounds from paraffins, naphthalene, indene, indane and the alkyl-substituted benzenes was trivial using the proposed solvent system. Highly satisfactory separation of the phenolic compounds from pyridines and aromatic nitriles was achieved. The separation of phenol from aniline, although satisfactory, was not as good. The optimum solvent to feed, water to solvent and hexane to feed ratios were identified as being 3.0, 5.0 and 0.25 respectively. Binary interaction parameters for the NRTL equation were obtained by regression of the equilibrium data from the batch extraction tests. The NRTL model fitted the equilibrium data satisfactorily. The proposed solvent system was tested on pilot plant scale. The performance of the extraction column was optimised using a synthetic feed stream consisting of m-cresol, p-cresol, aniline and o-tolunitrile. The optimum solvent ratios and operating parameters were then implemented in further tests on an industrial heavy naphtha stream. A phenolic product purity of 99.75% was achieved for this stream. The corresponding phenolic recovery was in excess of 91 %. The proposed separation process, including solvent recovery was simulated using the NRTL model with the experimentally determined interaction parameters. A single stream consisting of all the components used in the batch extraction tests was specified as the feed stream to the simulated process. A final simulated phenolic product purity of 99.5% and recovery in excess of 94% was obtained after solvent recovery. The optimum solvent to feed, hexane to feed and water to solvent ratios were determined as being 3.0, 5.0 and 0.25 in both the pilot plant tests and the simulated extraction process. It can be concluded that the proposed separation process is successful in recovering high purity phenolic compounds from tar liquors. Further development of the process has commenced in industry. / AFRIKAANSE OPSOMMING: Die pirolise van steenkool is 'n belangrike bron van fenoliese verbindings. Die skeiding van die fenoliese komponente vanuit die neutrale olies ook teenwoordig in die pirolise mengsel word bemoeilik deur lae relatiewe vlugtighede en die vorming van aseotrope. Dit is dus nie moontlik om die gewenste hoë fenoliese herwinning en fenoliese produk suiwerheid van 99.5% d.m.v. konvensionele distilleerprosesse te behaal nie. Alternatiewe prosesse soos ekstraktiewe distillasie en vloeistof-vloeistof ekstraksie met verskeie laagkokende oplosmiddels en mengsels van hoogkokende oplosmiddels is al ondersoek. Die hoë oplosmiddel verhoudings wat benodig word, lae herwinning van die hoërgesubstitueerde fenoliese verbindings, onvermoë om in een prosesstap 'n prosesstroom met In wye kookgebied te behandel en die ingewikkelde suiwering van die fenoliese produk tel onder die nadele van hierdie prosesse. 'n Oplosmiddelsisteem wat In selektiewe oplosmiddel, water as polêre oplosmiddel en heksaan as teenoplosmiddel bevat is as 'n alternatiewe proses voorgestel. 'n Industriële swaar nafta prosesstroom is ge-analiseer en die fenoliese verbindings, neutrale olies en stikstofbasisse met die hoogste konsentrasies daarin geïdentifiseer. Drie sintetiese strome is op grond van hierdie analise saamgestelom die industriële stroom te verteenwoordig: 1. fenol + benzonitriel + anilien + mesitileen + 5-et-2-me-piridien 2. m-kresol + o-tolunitriel +o-toluïdien + pseudokumeen + undekaan + indeen 3. 2,4-xilenol + 3,5-xilenol + 3,4-xilenol + indaan + dodekaan + naftaleen Die fenolbevattende stroom is as basis vir oplosmiddelkeuring gebruik, met die klem op die skeiding van fenol vanuit benzonitriel. Verskeie molekules wat hidroksie- en eter funksionele groepe bevat is as potensiële oplosmiddels uitgeken d.m.v. rekenaargesteunde molekulêre ontwerp met In genetiese algoritme. Hierdie oplosmiddels is d.m.v. enkellading ekstraksie toetse geëvalueer. Die kommersieel beskikbare oplosmiddel wat die hoogste fenol-benzonitriel, fenol-anilien en fenol-5-et-2-me-piridien skeidingsfaktore, sowel as die hoogste fenol herwinning op enkellading ekstraksie toetsvlak gelewer het, was triëtileenglikol. Vanuit die proses vir die keuse van 'n oplosmiddel was dit duidelik dat, vir hierdie skeidingsprobleem, die mees effektiewe oplosmiddels dié is met hidroksiel groepe wat so geposisioneer is in die oplosmiddel molekuul dat dit waterstofbindings kan vorm met meer as een fenoliese molekuul. Twee oplosmiddels wat nie kommersiëel beskikbaar is nie, 1,3-(etoksie-2-hidroksie)-propaan-2-01 en 1,3-(diëtoksie-4-hidroksie)-propaan-2- ol, is gesintetiseer vanuit etileenglikol en diëtileenglikol onderskeidelik. Die molekulêre strukture van hierdie twee oplosmiddels is analoog aan dié van triëtileenglikol en bevat 'n addisionele hidroksielgroep. Die effektiwiteit van die gesintetiseerde oplosmiddels is geëvalueer en met dié van triëtileenglikol vergelyk op grond van rn-kresol-o-tolunltriel, 2,4-xilenol - o-tolunitriel en 2,4-xilenol - o-toluïdien skeidingsfaktore en fenoliese herwinning behaal d.m.v. enkellading ekstraksie toetse. Hoër fenoliese herwinning en laer skeidingsfaktore is behaal met 1,3-(diëtoksie-4-hidroksie)-propaan-2-01as met triëtileenglikol. Triëtileenglikol is dus gekies vir verdere prosesontwikkeling aangesien dit kommersiëel beskikbaar is. Enkellading ekstraksie toetse is op elk van die sintetiese voerstrome uitgevoer met die voorgestelde oplosmiddelsisteem. Fenol- en m-kresol herwinning van meer as 99% en xilenol herwinning van meer as 98% is behaal. Die skeiding van fenoliese verbindings vanuit paraffiene, naftaleen, indeen, indaan en die alkielgesubstitueerde benseenverbindings is triviaal met die voorgestelde oplosmiddelsisteem. Hoogs aanvaarbare skeiding van fenoliese verbindings van die piridiene en aromatiese nitriele is vermag. Die skeiding van fenol en anilien is nie so goed nie, maar is nog steeds aanvaarbaar. Die optimum oplosmiddel tot voer, water tot oplosmiddel en heksaan tot voer is as 3.0, 5.0 en 0.25 vasgestel. Binêre interaksie parameters vir die NRTL vergelyking is verkry d.m.v. regressie van die ewewigsdata wat deur die enkelladingstoetse gegenereer is. Die NRTL model het die ewewigsdata goed gepas. Die voorgestelde oplosmiddelsisteem is op loodsaanlegvlak getoets. Die werking van die ekstraksie kolom is ge-optimeer met In sintetiese voerstroom wat uit m-kresol, pkresol, anilien en o-tolunitriel bestaan. Die optimum oplosmiddel verhoudings en bedryfstoestande is verder toegepas op 'n industriële swaar naftastroom. 'n Fenoliese suiwerheid van 99.75% is behaal met hierdie stroom. Die ooreenkomstige fenoliese herwinning was groter as 91%. Die voorgestelde skeidingsproses, insluitende oplosmiddelherwinning is gesimuleer met die NRTL model wat op die eksperimentele data gepas is. 'n Enkele stroom wat bestaan het uit al die komponente wat in die enkelladingstoetse gebruik is, is as die voerstroom tot die gesimuleerde proses gespesifiseer. 'n Finale gesimuleerde fenoliese produksuiwerheid van 99.5% en herwinning groter as 94% is na oplosmiddelherwinning behaal. Die optimum oplosmiddel tot voer, heksaan tot voer en water tot oplosmiddel verhoudings is vasgestel as 3.0, 5.0 en 0.25 onderskeidelik vir beide die gesimuleerde proses en die loodsaanleg toetse. Die voorgestelde skeidingsproses kan dus 'n hoogs suiwer fenoliese produk uit pirolisestrome herwin. Verdere ontwikkeling van die proses is in die industrie begin.

Thesis (MScAgric (Viticulture and Oenology))--Stellenbosch University, 2008. / The production of good quality wine is essential to ensure competitiveness on an international level. Wine quality is usually evaluated for the visual, olfactory and taste characteristics of that specific wine. The winemaking process starts with the grapes in the vineyard followed by oenological practises in the winery until the final wine is bottled. Factors that could influence wine quality include the grape quality from which the wine is made and different techniques used during wine production. Other factors include the presence as well as the interaction between microorganisms found in the grape juice and wine, and the biochemical effect these microorganisms have on certain chemical compounds in the wine. The different microorganisms found in grape juice and wine can either have a negative or positive contribution to the final quality of the wine. During certain stages of the winemaking process the growth and metabolic activity of certain microorganisms is a necessity to produce good wine. During other stages the presence of certain microorganisms can lead to the development of compounds that is regarded as off-flavours and therefore lead to unpalatable wines of low quality. Yeast strains that naturally present on the grapes and in the winery can also contribute to the final quality of the wine. Brettanomyces yeasts are part of the natural flora of winemaking and can drastically influence the aroma characters of a wine through the production of volatile phenols. The general aroma descriptions of volatile phenols include "smoky", "spicy", "barnyard", "animal" and "medicinal". Although some wine drinkers believe that these characters can add to the complexity of a wine, high levels of volatile phenols is mostly regarded as off-flavours and mask the natural fruity flavours of a wine. With this study we wanted to generate a better understanding of the effect of different winemaking practises on the production of volatile phenols by B. bruxellensis. We evaluated the difference in volatile phenol production when B. bruxellensis was introduced before or after alcoholic fermentation. We have shown that B. bruxellensis could grow and produce volatile phenols during alcoholic fermentation. Results obtained also showed that commercial wine yeast strains could produce the vinyl derivatives that serve as precursors for Brettanomyces yeast to produce the ethyl derivatives. The commercial yeast strains differed in their ability to produce vinyl derivatives. Different malolactic fermentation scenarios were evaluated, namely spontaneous versus inoculated, and with or without yeast lees. Results showed that spontaneous malolactic fermentation had higher volatile phenol levels in the wine than inoculated malolactic fermentation. The treatment with lees reduced the level of volatile phenols, probably due to absorption by yeast cells. The presence of the phenyl acrylic decarboxylase (PAD1) gene and the production of volatile phenols by S. cerevisiae commercial yeast strains were evaluated in Shiraz grape juice and in synthetic grape juice. The results indicated that the yeast strains differ in their ability to produce 4-vinylphenol and 4-vinylguaiacol. All the yeast strains tested had the PAD1 gene. We also evaluated the presence of the phenolic acid decarboxylase (padA) gene and the ability of different lactic acid bacteria strains to produce volatile phenols in synthetic wine media. Although some of these strains tested positive for the phenolic acid decarboxylase gene most of them only produced very low levels of volatile phenols. This study made a valuable contribution on the knowledge about the effect of Brettanomyces yeast on the volatile phenol content of red wines during different stages of the winemaking process and when applying different winemaking practices. It also showed the effect between Brettanomyces yeast and other wine microorganisms and the possible influence it could have on the final quality of wine. Research such as this can therefore aid the winemaker in making certain decisions when trying to manage Brettanomyces yeast spoilage of wines.

Thesis (MScAgric)--Stellenbosch University, 1970. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (PhD (Food Science))--University of Stellenbosch, 2006. / The aim of the study was to provide the South African wine industry with guidelines for the production of Pinotage wines with optimal total antioxidant capacity (TAC), while retaining sensory quality. The contribution of individual phenolic compounds to the wine TAC is important in this regard. The wine TAC was measured with the 2,2 -azino-di(3-ethylbenzo-thiazoline-sulphonic acid radical cation) (ABTS +) scavenging assay. The contributions of individual phenolic compounds to the wine TAC were calculated from their content in the wines and the Trolox equivalent antioxidant capacity (TEAC) of pure phenolic standards. The effects of climate region, vine structure, enological techniques (pre-fermentation maceration, juice/skin mixing, addition of commercial tannins, extended maceration) and maturation (oak barrels, alternative oak products, oxygenation) on the phenolic composition, TAC and sensory quality of Pinotage wines were also investigated. The TEAC values of quercetin-3-galactoside, isorhamnetin and peonidin-3-glucoside were reported for the first time. TEAC values observed for most compounds were much lower than those reported previously, although TEAC values for gallic acid, caftaric acid, caffeic acid and kaempferol were consistent with some previous reports. Caftaric acid and malvidin-3-glucoside were the largest contributors to the wine TAC. The contents of monomeric phenolic compounds and procyanidin B1, however, only explained a small amount (between 11 and 24%) of the wine TAC, with the remaining TAC attributed to oligomeric and polymeric phenolic compounds and other unknown compounds. Some synergy between different monomeric phenolic compounds was also demonstrated. All the viticultural and enological factors investigated affected the phenolic composition of Pinotage wines, while the wine TAC was only affected by some treatments. Changes in wine TAC could not always be explained by changes in phenolic composition as the contribution of oligomeric, polymeric and unknown compounds could not be assessed, but could play a large role. Differences in wine colour were also difficult to explain due to the large number of factors involved and the dark wine colour, which made objective measurements difficult. The concentration of vitisin A, an orange-red pyranoanthocyanin, was increased consistently as a result of prefermentation maceration treatments and affected the wine colour of oxygenated wines. Increased wine TAC was observed when cultivating Pinotage grapes on bush vines and in cooler climatic regions, compared to cultivation on trellised vines in warmer climatic regions. All the climatic regions and vine structure treatments, however, resulted in wines with good sensory quality. In terms of enological techniques, pumping-over, as opposed to punching-down and rotor treatments, is not recommended as a juice/skin mixing technique, due to reduced wine TAC, colour and sensory quality. Pre-fermentation maceration, addition of commercial tannin preparations, and oak maturation using traditional and alternative treatments, resulted in improved sensory quality, but with no change in wine TAC. However, optimisation of the tannin addition protocol may result in increased wine TAC if additions are made after fermentation or higher dosages are used. Oxygenation of Pinotage wine needs further investigation to optimise the protocol, as improvements to the wine colour and fullness were observed for some treatments, but loss of sensory quality and TAC were observed in most cases.

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The phenolic content of wine is responsible for determining characteristics such as the organoleptic qualities, colour stability, ageing properties and health-beneficial effects associated with wine. The aim ofthis study was to investigate the possibilities offered by capillary electrophoresis (CE) as an alternative separation technique to high performance liquid chromatography (HPLC) for the analysis of polyphenols in wine. The complexity of wine samples was the cause that neither technique was capable of a satisfactory singlestep analysis of wine. Suitable sample preparation techniques such as Sephadex- and Sep- Pak fractionation and ether extraction of wine polyphenols were investigated. These techniques did not, however, prove to be universal. A novel form of sample preparation namely a process analogous to lyophylization used to separate wine volatiles from nonvolatiles was introduced. The versatility of CE was further investigated in an attempt to eliminate the need for sample preparation. The use of polyvinylalcohol (PVA) coated capillaries, micellar electrokinetic chromatography (MEKC) and capillary gel electrophoresis (CGE) were investigated in this regard. Although none of these techniques could offer conclusive results, useful applications were forthcoming and routes for further investigation were outlined. Liquid chromatography coupled to electro spray ionisation mass spectroscopy (LC-ESI-MS) and capillary electrophoresis coupled to electro spray ionisation mass spectroscopy (CE-ESI-MS) were compared for the analysis of polyphenols in wine. While the latter technique could not produce sufficient separation compared to the former, future development ofCE-ESI-MS should make it a powerful technique for these analyses. / AFRIKAANSE OPSOMMING: Die fenoliese komponente in wyn speel 'n bepalende rol by eienskappe soos die organoleptiese karakter, kleur stabiliteit, verouderingspotensiaal en gesondheids-voordele wat met wyn geassosieër word. Die doel van hierdie projek was om ondersoek in te stel na die potensiaal wat kapillêre elektroforese (CE, "capillary electrophoresis") as 'n alternatiewe skeidingstegniek teenoor hoë druk vloeistof chromatografie (HDVC) vir die analise van die polifenole in wyn bied. Die kompleksiteit van wyn monsters is van so 'n aard dat 'n bevredigend enkelstap analise met geeneen van die tegnieke moontlik is nie. Gepaste monster-voorbereidingstappe soos Sephadex- en Sep-Pak fraksionering asook eter ekstraksie van die polifenole in wyn is ondersoek. Geeneen van die tegnieke was egter universeel toepaslik nie. 'n Nuwe metode van monster-voorbereiding, naamlik 'n proses analoog aan liofilisasie wat gebruik word om die wyn te skei in vlugtige en nievlugtige komponente is gedemonstreer. Die veelsydigheid van CE was gevolglik ondersoek in 'n poging om monstervoorbereiding uit te skakel. Die gebruik van polyvinielalkohol-(pVA) bedekte kapillêre, missellêre elektrokinetiese chromatografie (MEKC) en kapillêre gel elektroforese (CGE, "capillary gel electrophoresis) is in hierdie verband ondersoek. Alhoewel geeneen van hierdie tegnieke onweerlegbare resultate gelewer het nie, het bruikbare toepassings hieruit voortgespruit en is die grondslag vir verdere navorsing gelê. Vloeistof chromatografie gekoppel aan eIektrosproei ionisasie massaspektroskopie (LCESI- MS) en kapillêre elektroforese gekoppel aan elektrosproei ionisasie massaspektroskopie (CE-ESI-MS) is vergelyk vir die analise van polifenole in wyn. Alhoewel laasgenoemde tegniek onvoldoende skeiding lewer vergeleke met eersgenoemde, behoort toekomstige ontwikkelinge op die gebied van CE-ESI-MS dit 'n kragtige tegniek vir die analise van hierdie monsters te maak.

The concentration of phenols in the soils environment and their fate was studied as a function of five different soil types, six different monohydroxyphenols, and three different municipal landfill leachates media. Concentrations of naturally occurring phenols were also followed for a period of one year in young and old leachates. Methods for analysis of phenols were reviewed for quantitative and qualitative analysis of phenols in landfill leachates. To determine the adsorptive capabilities of the soils used in this study, the isotherm approach was used after the equilibration time of phenols in soils was determined to be five days. Concentrations of phenols varying from 5 ppm to 100 ppm were used to construct isotherm graphs. The soil-phenol isotherm curves conformed very well to the Freundlich equation, indicating multiple adsorption mechanisms and slow equilibration times in the soilsphenols reactions. A statistical analysis of the isotherm data showed %-free iron oxides to be the most important soil characteristic for the adsorption of phenols by all soils; followed by soil pH and % clay in order of significance. High solubility and moderate polarity of phenols also were found to be favorable factors in the adsorption of phenols by soils. Naturally occurring phenols such as cresols disappeared fastèr from soil solutions than synthetic phenols. The reactivities of phenols with MSW leachates increased with the age of the leachates. Very young leachates, having low pH and high TOC levels favored synthetic phenols over naturally occurring phenols to react with. All leachates studied demonstrated an ability to remove from solution one or more of the six phenols used in large quantities over a period of 15 days or less. The overall performance of the leachates used in this study seemed to be a function of the humic acid levels found in them. Levels of naturally occurring phenols in leachates varied from several ppbs to more than 9000 ppbs for a year's period. The highest phenol levels were found in the young phenols and the lowest levels in the old phenols; indicating that pH and TOC concentration determine the amounts of phenols in solution. In column studies of perfusion of leachates through 10 cm of soil materials packed at field densities, no soil was able to stop the migration of phenols for more than 5 to 10 pore volume displacements. Low pH and high TOC levels seemed to play a much larger role in the migration of phenols through soils than the levels of phenols found in the leachates used. The use of phenol enriched deionized water passed through soil columns showed the fact that there is a clear dependency of adsorption of phenol on the flow rate. Slow rates favored adsorption of phenol by all soils studied. The TOC analysis of the effluents from the phenol enriched water-soil columns studies indicated that some mechanisms for the disappearance of phenol from soil solution may have been transformation reactions as well as adsorption reactions. Varying TOC levels with flux seemed to indicate that these reactions are much slower than the adsorption reactions. The use of Cu⁺² saturated soils in an attempt to correlate transformation reactions of phenol with transition metal catalytic properties failed to increase the adsorption and/or transformation of phenol in the soil media. The 4-aminoantipyrine colorimetric method performed well in the analysis of phenols in air unstable leachates. Gas-liquid chromatography using NPGSB+H₃PO₄ on Anakrom A 90/100 mesh was used for the quantitative and qualitative analysis of phenols in leachates.

Candida tropicalis yeast and bacteria Comamonas testosteroni have been considered to be able to metabolize phenol and utilize it as the only source of carbon and energy. In our laboratory we investigated the cytoplasmic enzymes responsible for the first and second step of phenol degradation, NADPH-dependent phenol hydroxylase of both C. tropicalis and C. testosteroni and catechol 1,2-dioxygenase of C. tropicalis. The aim of our study was to isolate and partially characterize those enzymes. Phenol hydroxylase purification consisted of preparation of cytosol from C. tropicalis yeast by fraction centrifugation, chromatography and re-chromatography on a column of DEAE Sepharose, fractionation by precipitation of the enzyme with polyethylene glycol 6000 and gel permeation chromatography on a column of Sephacryl S-300. Extracellular phenol hydroxylase of C. testosteroni was purified by fraction precipitation with polyethylene glycol 6000 and by gel permeation chromatography on 4B Sepharose and Sephacryl S-300. Catechol 1,2-dioxygenase was purified using the procedure consisting of: chromatography and re- chromatography on a column of DEAE Sepharose, lyophilization of the enzyme and gel permeation chromatography on a column of Sephadex G-100. The enzyme activity was determined by two methods: use of HPLC...

Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2015. / Rooibos iced tea (RIT), as one of the products of Rooibos is fast becoming very popular as a beverage in society due to the benefits of the phenolic compounds that are associated with this herbal tea. Some of the commercially available products have been found to contain, if any, lower contents of the major phenolic compounds, namely aspalathin and its oxidation products, iso-orientin and orientin. Their presence is considered as indicators of a good quality product. The purpose of this study was to investigate the effect of ultraviolet-C (UV-C) light as an alternative treatment to heat treatment on the shelf life, pH, phenolic composition, colour and microorganisms associated with Rooibos. Two formulations of RIT were used in order to determine the efficacy of the UV-C on the shelf life whilst three formulations were used for the physicochemical analysis. Only one formulation was used for inoculation with three spoilage bacteria, yeast and mould spoilage microorganisms namely; Escherichia coli K12, Staphylococcus aureus, Salmonella sp., Saccharomyces cerevisiae and Cladosporium sp. The UV-C dosages of 0, 918, 1 836, 2 754 and 3 672 J.l -1 were used to treat the RIT using a pilot-scale UV-C system with a turbulent flow at a constant flow rate of 4000 l.hr-1 . A log count of 4 log10 was considered the limit for the spoilage growth since it is the average log10 afternormal pasteurisation. The use of UV-C treatment was found to have significantly (p1) effect on the overall colour difference of the RIT in formulations A, B, and C. All the spoilage microorganisms were significantly reduced by UV-C dosage to less than 4 log10 except the Cladosporium sp. The S. cerevisiae was the most sensitive microorganism whilst Cladosporium sp. was the most resistant. The effect of UV-C on the spoilage microorganism followed the sequence: S. cerevisiae>Salmonella sp.>S. aureus>E. coli K12>Cladosporium sp. This study indicated that microbiological reduction was achieved as a function of increasing UV-C dosage. In order to achieve the highest log10 reduction, the highest UV-C dosage of 3 672 J.l-1 may be used. However, the dosage may need to be increased in order to achieve the desired results in the treatment of Cladosporium sp. It can thus be concluded from the above investigations that UV-C dosage treatment of 3 672 J.l-1 is optimum in the non-thermal treatment of RIT / South African Association for Food Science & Technology Cape Peninsula University of Technology Bursary

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / Wines contain a number of phenolic compounds, belonging to non-flavonoid and flavonoid complexes. Phenolic compounds in wine are responsible for wine colour, astringency, and bitterness. Saccharomyces cerevisiae yeast is normally used in winemaking but it has been proved to decrease the phenolic content in wines. Current research on the use of non-Saccharomyces yeast in winemaking has produced better quality wines than S. cerevisiae yeast therefore improving the sensory profile of wine. This study evaluated effect of Torulaspora delbrueckii yeast on the phenolic content of experimental wines derived from Chenin blanc grapes. A reversed phase high-performance liquid chromatographic (RP-HPLC) method was used for the identification and quantitation of the phenolic compounds. The difference test method was used to determine the sensory attributes of wines. The data was subjected to analysis of variance to compare treatment differences between the wines and principal component analysis to establish possible correlation between the data sets. Furthermore, a gas chromatographic-flame ionization detection method (GC-FID) was used for the quantification of volatile compounds in the wines. In this work, wines made with T. delbrueckii strain M2/1 had high concentration of (+)-catechin, caffeic acid, ferulic acid and p-coumaric acid in all studied vintages. Wines made with VIN13 had higher concentrations of flavan-3-ols, compared to wines made with M2/1 and 654. In sensory evaluation, M2/1 wines were prominent in astringency and complexity. Yeast strain M2/1, also attributed to body and complexity of the wine. However, in this study no correlations were observed between the phenolic content and sensory attributes and vice versa. The quality of wine cannot be concluded by chemical or sensory analysis alone, but the data sets are complementary. Although the phenolic concentration of wines made with S. cerevisiae strain (VIN 13) and T. delbrueckii (M2/1) were similar in measured phenolic concentrations, they had different sensory attributes. Wines made during the 2013 vintage indicated the importance of the use of a strain with higher enzyme activity and high fermentation rate. There is minimal to no skin contact in white winemaking. Therefore, the use of a yeast strain with an increased enzyme activity can facilitate the extraction of phenolics from grape, resulting in wine with improved quality.