Thesis (PhD)--Stellenbosch University, 2002 / ENGLISH ABSTRACT: Prototypes of a new polymer S02 gas-generating sheet for the control of Botrytis cinerea during the post-harvest storage of table grapes, were developed and manufactured for evaluation using a pilot scale production plant. Attention was paid to the appearance of the sheet, in order to make it technologically efficient as well as aesthetically acceptable to both industry and consumers. The storage quality of semi-commercial export consignments of various cultivars table grapes packed with the monolithic thin-film polymer S02 slow release sheet, was evaluated and compared to results obtained using the locally manufactured Uvasys S02 sheet. The following were investigated: the efficacy of the new polymer sheets in controlling storage decay, the stage at which S02 damage is manifested on table grapes, the level of S02 damage associated with different S02 concentrations, whether S02 damage is manifested more readily at a particular position on the bunch, and the possible effect of an increase in storage temperature, from an initial storage at -O.5°C to 10°C, on the levels of S02 bleaching. Results showed that the new polymer S02 sheet compared favourably with the existing, commercially available Uvasys S02 sheets. The exact S02 concentration required for effective decay control varied for different cultivars, as well as for the different types of grape packages. The S02 concentration incorporated within the sheet was shown to be lower for grapes packed in non-perforated bags, and slightly higher for those in perforated bags. Differences between cultivars occurred with regard to the level of control and the levels of S02 damage. Levels of S02 damage were also significantly affected by the storage period and temperature fluctuations. No significant differences in the levels of decay development and S02 damage were observed in relation to the orientation of the bunches in the carton. The extent of damage incurred to grape tissue by the absorption of S02 gas was determined by low-temperature scanning (LTSEM) and transmission electron microscopy (TEM) techniques. LTSEM and TEM micrographs of areas damaged by S02 gas revealed that exposure to S02 gas may lead to plasmolysis and the loss of cellular fluids. Although damage to the cell walls, cell wall structures and cell membranes, caused by S02 gas, was more prominent in the tissue layers nearer to the fruit surface, damage also occurred to a lesser extent in deeper tissue layers. S02 gas release-rate studies of polymer S02 sheets containing various concentrations Na2S205 revealed that levels of S02 gas emitted depended largely on the levels of Na2S205 incorporated into the sheets. Higher levels of S02 gas were released with the polymer sheets of higher concentrations Na2S205. The release curve for the commercial Uvasys S02 sheet was very different to that of the polymer sheets, with much higher levels of S02 gas emitted initially by the Uvasys S02 sheet compared to the polymer sheets, while the polymer sheets emitted low levels of S02 gas for longer periods compared to the Uvasys S02 sheet. The manufacturing process and the pilot scale production plant that was developed and constructed was successfully used to manufacture polymer S02 generating sheets that are technically sound and efficient, and aesthetically acceptable to industry. The efficacy of such sheets, regarding levels of decay control and S02 damage, was similar to that obtained with the presently available, commercially used Uvasys S02 sheet. / AFRIKAANSE OPSOMMING: 'n Nuwe polimeriese S02-gasvrystellingsvel vir die beheer van Botritis cinerea gedurende die na-oes opberging van tafeldruiwe is ontwikkel en vervaardig. 'n Nuwe loodsaanleg is spesiaal vir hierdie doel ontwerp en gebou. Aandag is geskenk aan die voorkoms van die velle aangesien dit belangrik is dat die nuwe velle beide tegnologies effektief en esteties aanvaarbaar moet wees vir die sagtevrugtebedryf en verbruikers. Die opbergingskwaliteit van semi-kommersiële uitvoerbesendings van verskeie kultivars tafeldruiwe, verpak met die nuwe monolitiese S02- gasvrystellingsvelle, is bepaal. Die volgende is ook bepaal: die effektiwiteit van die nuwe polimeriese velle, die stadium waarby S02-skade op die druiwe duidelik word, die vlak van S02-skade wat met verskillende konsentasies S02-gas geassosieer is, die moontlike invloed wat 'n toename in temperatuur (vanaf -0.5° tot 1DOC) op die verbleiking deur S02 sal hê, en of die S02-skade by voorkeur in 'n sekere posisie op die druiwe sal plaasvind. Die nuwe S02-vel het baie goed vergelyk met die kommersieël beskikbare Uvasys S02-vel. Die S02-konsentrasie benodig vir die effektiewe beheer van Botritis cinerea beskadiging het egter van kultivar tot kultivar verskil. Die keuse van die tipe verpakking, geperforeerd of ongeperforeerd, het ook 'n rol gespeel. Die konsentrasie S02-gas benodig vir effektiewe beheer was laer wanneer die druiwe in die nie-geperforeerde sakke verpak was. Vlakke van S02-skade is ook noemenswaardig beïnvloed deur die opbergingsperiode en variasies in temperatuur. Daar was geen duidelike verskil in die ontwikkeling van bederf en S02-skade ten opsigte van die posisie van die trosse in die karton nie. Die mate van S02-skade aan vrugweefsel is deur middel van laetemperatuurskandeerelektronmikroskopie (LTSEM) en transmissieelektronmikroskopie (TEM) bepaal. Daar is bevind dat die blootstelling aan S02 moontlik tot plasmolise en die uitlek van sellulêre vloeistof kon lei. Alhoewel S02-skade aan die selwande en membrane meer prominent in die weefsel naby die oppervlak van die vrug was, het skade ook in die onderliggende lae plaasgevind. Die vlakke van vrygestelde S02-gas het grootendeels afgehang van die konsentrasie natriummetabisulfiet in die velle. Die S02-vrystellingskurwe van die nuut ontwikkelde polimeriese S02-velle het baie verskil van dié van die Uvasys vel. Laasgenoemde lewer aanvanklik 'n hoë konsentrasie vrygestelde S02-gas vir 'n kort periode, gevolg deur baie lae S02 vlakke daarna, terwyl eersgenoemde 'n laer aanvanklike S02 vrystelling het, gevolg deur vergelykederwys hoër S02 konsentrasies daarna. Die ontwikkelde vervaardigingsproses en die loodsaanleg wat daaruit voortgevloei het is dus suksesvol aangewend om goeie polimeriese S02- vrystellingsvelle te vervaardig. Hierdie velle is tegnies effektief vir die beheer van Bofrifis cinerea gedurende die na-oes verpakking van tafeldruiwe en is esteties aanvaarbaar vir die Suid Afrikaanse sagtevrugtebedryf.

Thesis (PhD(FoodSc))--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Potential beneficial and/or adverse modulatory effects of polyphenol-enriched extracts of rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.) on the antioxidant homeostasis in the liver were investigated. Phase II metabolism of aspalathin and mangiferin, the major polyphenols of rooibos and honeybush respectively, was assessed for potential glucuronidation and sulphation. Glucuronidation resulted in a loss of antioxidant activity for aspalathin and mangiferin in post-column HPLC-DAD-DPPH• and HPLC-DAD-ABTS•+ assays and also a decreased activity of iron chelating properties of mangiferin in the FRAP assay. Two independent studies for 28 and 90 days with polyphenol-enriched extracts (PEEs) of unfermented rooibos [Aspalathus linearis (PER)] and honeybush [Cyclopia. subternata (PECsub) and C. genistoides (PECgen)] in male Fischer rats were conducted to assess possible beneficial and/or adverse biological effects. PECgen was only included in the 28 day study. PEEs were characterised by in vitro antioxidant assays and HPLC analysis. The importance of detailed chemical characterization of rooibos and honeybush when investigating biological effects in vivo is clear as distinctive biological effects and major differences in compositions were evident. Biological parameters included were serum chemical parameters, activities of selected antioxidant enzymes, levels of glutathione and the modulation of expression of oxidative stress and antioxidant defense related genes in the liver. Sub-chronic (90 days) exposure of rats to PER and PECsub both adversely affected iron absorption significantly (P<0.05) and significantly (P<0.05) and markedly lowered levels of reduced glutathione (GSH) in the liver. The high levels of polyphenol intake were implicated and interaction with glutathione was postulated to occur via catechol o-quinone conjugations with GSH. This was also implicated in the significantly (P<0.05) increased activity of glutathione reductase (GR) following 28 days. These findings suggest that PEEs from rooibos and honeybush have the potential to alter the glutathione homeostasis, which could contribute to oxidative status in the liver. PECsub resulted in alterations in the liver biliary system which was manifested as significantly (P<0.05) increased serum total bilirubin (Tbili) and alkaline phosphatase (ALP), depending on the age of the rats, level of total polyphenols and duration of exposure. The expression of a number of oxidative stress and antioxidant defense related genes were differentially altered by the PEEs of rooibos and honeybush in rat liver and further indicated potential oxidative stress. Modulatory effects of PEEs on expression of 84 of these genes in rat liver were assessed with a quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) array and provided additional insights into the possible adverse and protective effects of rooibos and honeybush. Further investigation on total polyphenol dose levels and time of exposure in the application of PEEs of rooibos and honeybush as dietary supplements and functional foods is recommended and will also be of value in anticipated regulatory requirements for future substantiation of safety and efficacy. / AFRIKAANSE OPSOMMING: Die moontlike voordelige en/of nadelige modulerende effekte van polifenol-verrykde ekstrakte van rooibos (Aspalathus linearis) en heuningbos (Cyclopia spp.) op die antioksidant homeostasis in die lewer is ondersoek. Die fase II metaboliete van aspalatien en mangiferin, die hoof verbindings in rooibos en heuningbos onderskeidelik, is ondersoek t.o.v. glukuronidering en sulfonering. Glukuronidasie het gelei tot n verlies in antioksidant aktiwiteit van aspalatien en mangiferin soos bepaal in post-kolom HPLC-DAD-DPPH• en HPLC-DADABTS•+ toetse, asook verminderde interaksie met yster van mangiferin in die FRAP toets. Twee onafhanklike studies van 28 en 90 dae is onderneem met polifenol-verrykde ekstrakte (PVEs) van ongefermenteerde rooibos [Aspalathus linearis (PVR)] en heuningbos [Cyclopia. subternata (PVCsub) and C. genistoides (PVCgen)] in manlike Fisher rotte om die moontlike voordelige en/of nadelige biologiese effekte te ondersoek. PECgen was slegs in die 28 dae studie ingesluit. PVEs is gekarrakteriseer deur in vitro antioksidant en HPLC analises. Die belang van chemiese karaktirisering van rooibos en heuningbos tydens ondersoeke na biologiese aktiwiteit is duidelik aangesien verskeie en variërende biologiese aktiwiteite en verskille in die komposisie in die huidige studie gesien is. Die biologiese parameters wat ondersoek is om die effek van die PVEs te bepaal het serum kliniese parameters, aktiwiteit van geselekteerde ensieme, glutatioon en evaluering van die ekspressie van oksidatiewe en antioksidant verwante gene in die lewer, ingesluit. Sub-kroniese (90 dae) blootstelling van rotte aan PVR en PVCgen het yster absorpsie negatief beïnvloed. Die beduidende (P<0.05) verlaagde vlak van gereduseerde glutatioon in die lewer was toegeskryf aan die hoë vlakke van polifenole ingeneem tydens die studie en word moontlik veroorsaak deur n spesifieke katekol o-konjugasie van GSH. Hierdie interaksie was ook moontlik die oorsaak van n beduidende (P<0.05) toename in die aktiwiteit van glutatioon reduktase. Dié bevindinge het moontlike implikasies t.o.v die glutatioon homeostase en is n moontlike indikase dat PVEs van rooibos kan bydra tot oksidatiewe stres. PVCsub het veranderinge in die lewer gal-sisteem tot gevolg gehad aangesien daar n beduidende (P<0.05) verhoging in die serum totale bilirubin en alkalien fosfaat was. Hierdie veranderinge is beïnvloed deur die ouderdom, vlakke van die totale polifenole en die periode van blootstelling. Die uitdrukking van oksidatiewe en antioksidant verwante gene is op verskillende maniere beïnvloed deur die PVEs van rooibos en heuningbos in rot lewer and dien as n verdere indikasie van onderliggende oksidatiewe stres. Die modulerende effekte van PVEs op geenuitdrukking het gelei tot additionele insig aangaande die moontlike skadelike of beskermende eienskappe van PVEs vir gebruik as kruie produkte of dieet aanvullings. Die indikasies van moontlike oksidatiewe stres was duidelik van biologiese parameters en modulering van geenuitdrukking in die lewer, en vereis verdere ondersoek na die polifenool dosis en periode van toediening voordat PVEs van rooibos en heuningbos as funksionele voedsel produkte gebruik word. Hierdie ondersoek sowel as toekomstige ondersoeke in hierdie verband sal van waarde wees vir regulatoriese vereistes omtrent die veiligheid en effektiwiteit van rooibos en heuningbos kruie produkte.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2005. / The aim of this study was to investigate the effects of hot-deboning (1 h post-mortem) on the shelf-life and the physical meat quality characteristics, including tenderness, pH, purge (%), cooking loss (%), and raw meat colour of vacuum packed ostrich (Struthio camelus var. domesticus) meat cuts from the M. gastrocnemius, pars interna and the M. iliofibularis during post-mortem refrigerated aging for respectively 21 d at 4ºC and 42 d at -3º to 0ºC.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2005. / This study was undertaken in view of the high incidence of malnutrition problems such as protein-energy malnutrition and diabetes type 2 in countries like Botswana, and due to worldwide interest in underutilised and underdeveloped crops. Morama bean, the seed of Tylosema esculentum (family Fabacae), occurs naturally in the drier areas of Southern Africa, including Botswana, where it is, to a small extent, harvested as wild plant for human consumption. Due to the potential of this crop there is increasing interest in its cultivation. Despite its traditional use as food source in Botswana, little is known about its nutritional value, benefits and disadvantages, and its use as food was therefore the reason for this research. A specific aim was to improve the school feeding programme with this readily available indigenous product.

Thesis (MSc Food Sc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT:Aspalafhus linearis is an indigenous fynbos plant cultivated in the Clanwilliam area of the Western Cape, South Africa. The rooibos tea that is prepared from this plant, has become popular worldwide mainly due to the alleged health properties. Studies on the anti-microbial properties of green, black and oolong teas have shown that these teas have strong anti-microbial activity against a wide range of microbes. No studies have been done on the anti-microbial activity of rooibos tea and the aim of this study was to determine what impact rooibos tea extracts would have on the growth of different food spoilage and potential pathogenic microbes. Water and ethyl acetate extracts of fermented and unfermented rooibos tea were used to determine the inhibitory effect on the growth of an Escherichia coli strain. The E. coli culture was grown in tea-MRS with either added fermented or unfermented rooibos tea extracts. Both the water and ethyl acetate extracts showed a strong inhibitory effect against the E. coli strain in that there was a decrease in the final bacterial cell density (Nmax)(from 0.59 00 to 0.25 00) and the maximum specific growth rate (~max)(from 1.12 h-1 to 0.20 h-1) and an increase in the doubling time (~) (from 0.59 h to 1.80 h) and lag time (tlag)(from 4.81 h to 6.60 h) as the concentration of the soluble solids of the tea extracts was increased from 0.5 to 5.0 g.r1 . Furthermore, it was found that the fermented rooibos tea had a much stronger inhibitory effect (69% decrease in growth at 5.0 g.r1 soluble solids) compared to the unfermented rooibos tea extracts (35.1% decrease in growth at 5.0 g.r1 soluble solids). The resulting data indicated that rooibos tea had a very strong inhibitory effect on the growth of the E. coli strain. It was also found that the water extracts of rooibos tea showed a stronger inhibitory effect on the growth of the E. coli than the ethyl acetate extracts, indicating that the antimicrobial activity of rooibos tea is not exclusively due to the polyphenolic content - individual compounds. It was also determined that the rooibos tea water extracts showed a bacteriostatic action against the E. coli strain in that as soon as the tea is no longer part of the growth medium, the E. coli resumed a normal growth pattern. The data obtained showed that the inhibitory effect of rooibos tea water extracts (69% decrease in growth) against the growth of E. coli was more pronounced than that found when black tea water extracts (25.7% decrease in growth) at the same concentrations were used.Rooibos tea water extracts (0.5 - 5.0 g.r1) of fermented and unfermented tea were also used to determine the inhibitory effect on other food spoilage microbes and potential pathogens. Strains of Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Streptococcus mutans, Saccharomyces cerevisiae and Zygosaccharomyces rouxii were grown in the presence of fermented and unfermented rooibos tea water extracts. The effect that fermented rooibos tea had on the growth of all the microbes tested was in the following order: Staph. aureus (90.8% decrease in growth) > L. monocytogenes (89.2% decrease in growth) > Strep. mutans (84.1% decrease in growth) > B. cereus (80.3% decrease in growth) > Sacch. cerevisiae (77.7% decrease in growth) > E. coli (69.0% decrease in growth). The rooibos tea clearly had an inhibitory effect on the growth of all the microbes, with the exception of the Z. rouxii strain where the presence of the tea water extracts was found to enhance the growth. The inhibitory effect of rooibos tea on the growth of these microbes was shown by changes in the growth parameters with Nmax and IJmaxshowing decreases, while the ld and tlagincreased as the concentration of the tea soluble solids was increased. As with E. coli, the fermented rooibos tea water extracts showed the stronger inhibitory effect on the growth of the various microbes. The data obtained in this study suggests that rooibos tea is not effective as an anti-microbial agent against all yeast species, but will strongly retard the growth of specific Gram-positive and Gram-negative bacteria. As long as rooibos tea is present, strong anti-microbial activity will be observed at a cup of tea concentration of 2.5 g.r1 soluble solids. These results may be of value to support the health claims associated with rooibos tea and may in the future lead to the use of rooibos tea as a "natural" food preservative. / AFRIKAANSE OPSOMMING:Aspalathus linearis is 'n inheemse fynbosplant wat gekultiveer word in die Clanwilliam area van die Wes Kaap, Suid-Afrika. Rooibostee, wat gemaak word van hierdie plante, het baie gewild geword wereldwyd a.g.v. die gesondheidsaspekte van hierdie tee. Studies toon dat groen, swart en oolong tee sterk anti-mikrobiese aktiwiteit het teen 'n wye reeks mikrobes. Aangesien daar voorheen geen studies gedoen is op die anti-mikrobiese aktiwiteit van rooibostee nie, was die doel van hierdie studie om die effek van rooibostee te bepaal op die groei van verskillende voedselbederwers en potensiele patogeniese mikrobes. Water- en etielasetaat-ekstrakte van gefermenteerde en ongefermenteerde rooibos tee is gebruik om die inhiberende effek op die groei van Escherichia coli te bepaal. Escherichia coli is gegroei in tee-MRS met bygevoegde gefermenteerde of ongefermenteerde rooibostee-ekstrakte. Seide die water- en etielasetaatekstrakte van rooibostee het 'n sterk inhiberende effek gewys teen E. coli en dit word gestaaf deur 'n afname in die finale bakteriese seldigtheid (Nmax)(vanaf 0.59 00 tot 0.25 00) en die maksimum spesifieke groeitempo (lJmax) (vanaf 1.12 h-1 tot 0.20 h-1) en 'n toename in die verdubbelingstyd (~) (vanaf 0.59 h tot 1.80 h) en die sloerfase (tlag)(vanaf 4.81 h tot 6.60 h) 5005 wat die konsentrasie van oplosbare vastestowwe van die tee toeneem van 0.5 tot 5.0 g.r1 . Verder is daar gevind dat die gefermenteerde rooibostee 'n baie sterker inhiberende effek het (69% afname in groei by 5.0 g.r1 oplosbare vastestowwe) in vergelyking met die ongefermenteerde rooibostee-ekstrakte (35.1% afname in groei by 5.0 g.r1 oplosbare vastestowwe). Die resultate van die data dui aan dat rooibos tee 'n baie sterk inhiberende effek het op die groei van die E. coli spesie. Die waterekstrakte van rooibostee het 'n sterker inhibisie getoon teen die groei van E. coli as die etielasetaat-ekstrakte, wat aandui dat die anti-mikrobiese aktiwiteit van rooibostee nie eksklusief toegeskryf kan word aan die polifenoliese samestelling nie. Daar is ook gevind dat rooibostee water-ekstrakte 'n bakteriostatiese effek het teen E. coli, want sodra die tee ekstrakte nie meer teenwoordig is in die groeimedium nie, hervat E. coli normale groei. Die data wys ook dat die inhiberende effek van rooibostee water-ekstrakte (69.0% afname in goei) teen E. coli baie sterker is as die van swart tee water-ekstrakte (25.7% afname in groei) by dieselfde konsentrasies.Rooibostee water-ekstrakte (0.5 - 5.0 g.r1) van gefermenteerde en ongefermenteerde rooibostee is ook gebruik om die inhiberende effek te bepaal teen ander voedselbederwers en potensiele patogene. Spesies van Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Streptococcus mutans, Saccharomyces cerevisiae en Zygosaccharomyces rouxii is gegroei in die teenwoordigheid van gefermenteerde en ongefermenteerde rooibostee waterekstrakte. Die effek wat gefermenteerde rooibostee het op die groei van die getoetste mikrobes is 5005 volg: Staph. aureus (90.8% afname in groei) > L. monocytogenes (89.2% afname in groei) > Strep. mutans (84.1% afname in groei) > B. cereus (80.3% afname in groei) > Sacch. cerevisiae (77.7% afname in groei) > E. coli (69.0% afname in groei). Rooibostee het 'n duidelike inhiberende effek gehad teen al die organismes, behalwe teen Z. rouxii spes ie, waar die teenwoordigheid van rooibostee die groei van die organisme bevorder het. Die inhiberende effek van rooibostee teen die groei van hierdie mikrobes word ondersteun deur die groei parameters waar die Nmaxen IJmaxafgeneem het terwyl die ~ en tlagtoegeneem het 5005 wat die konsentrasie van die oplosbare vastestowwe toeneem. Die gefermenteerde rooibostee water-ekstrakte het ook 'n sterker inhiberende effek op die groei van die verskillende mikrobes net 5005 met E. coli. Die data wat verkry is van hierdie studie dui aan dat rooibostee nie effektief sal wees as 'n anti-mikrobiese middel teen aile gis spesies nie, maar dit sal die groei van spesifieke Gram-positiewe en Gram-negatiewe bakterie sterk vertraag. So lank as wat rooibostee teenwoordig is, sal sterk anti-mikrobiese aktiwiteit waargeneem word by 'n koppie-tee konsentrasie van 2.5 g.r1 oplosbare vastestowwe. Hierdie resultate kan help om die gesondheidseienskappe geassosieer met rooibostee te ondersteun en help om die gebruik van rooibostee as 'n "natuurlike" preserveermiddel te bevorder. dedicated to my parents

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The World Health Organisation (WHO) estimates that at least 75% of infants receive infant formula milk (IFM) either entirely or in conjunction with breast milk during the first four months after birth. The presence of the emerging pathogen Enterobacter sakazakii in IFM has been associated with rare but fatal cases of neonatal infections and deaths. There is thus a need for accurate methods for the rapid detection of E. sakazakii in foods. At present, the methods used to detect and identify this micro-organism are inadequate, controversial and contradictory. The aim of this study was to determine the most suitable method for E. sakazakii detection after evaluation of the currently available methods. A further aim was to optimise a polymerase chain reaction (PCR) method for the detection of only viable E. sakazakii cells utilising the DNA-intercalating dyes ethidium monoazide (EMA) and propidium monoazide (PMA). The Food and Drug Administration (FDA) method for E. sakazakii detection was utilised to select 50 isolates from IFM and 14 from the environment, regardless of colony appearance. These isolates were identified by sequencing a 1.5 kilobase (kb) fragment of the 16S ribosomal DNA (rDNA) and by using the National Centre for Biotechnological Information (NCBI) database to confirm the closet known relatives. Seven of the 50 (14%) IFM isolates and six of the 14 (43%) environmental isolates were identified as E. sakazakii. The methods that were evaluated for accuracy in detecting and identifying these E. sakazakii isolates included yellow pigment production on tryptone soy agar (TSA), chromogenic Druggan-Forsythe-Iversen (DFI) and Enterobacter sakazakii (ES) agars and PCR using six different species-specific primer pairs described in the literature. The suitability of the FDA method was lowered by the low sensitivity, specificity and accuracy (87%, 71% and 74%, respectively) of using yellow pigment production for E. sakazakii identification. DFI and ES agars were shown to be sensitive, specific and accurate (100%, 98% and 98%, respectively) for the detection of E. sakazakii. The specificity of the PCR amplifications was found to vary between 8% and 92%, with Esakf and Esakr being the most accurate of the primer pairs evaluated. The current FDA method for E. sakazakii detection requires revision in the light of the availability of more sensitive, specific and accurate detection methods. Based on the results obtained in this study, a new method is proposed for the detection of E. sakazakii in food and environmental samples. This proposed method replaces the culturing steps on violet red bile glucose agar (VRBGA) and TSA with culturing on chromogenic DFI or ES agar. For identification and confirmation of presumptive E. sakazakii isolates, the oxidase test, yellow pigment production and API biochemical profiling is replaced by DNA sequencing and/or species-specific PCR with the most accurate primer pair (Esakf and Esakr). The amendments to the current FDA method will reduce the time to detect E. sakazakii from approximately 7 days to 4 days and should prove to be more sensitive, specific and accurate for E. sakazakii detection. In this study, a novel PCR-based method was developed which was shown to be capable of discriminating between viable and dead E. sakazakii cells. This was achieved utilising the irreversible binding of bacterial DNA to photo-activated PMA or EMA in order to prevent PCR amplification from the dead cells. At concentrations of 50 and 100 μg.ml-1, PMA completely inhibited PCR amplification from dead cells, while causing no significant inhibition of the PCR amplification from viable cells. EMA was equally effective in preventing PCR amplification from dead cells, however, it also inhibited PCR amplification from viable cells. PMA-PCR in particular, will be useful for assessing the efficacy of processing techniques, as well as for monitoring the resistance, survival strategies and stress responses of E. sakazakii. This will be an important step in the efforts to eliminate E. sakazakii from food and food production environments. / AFRIKAANSE OPSOMMING: Die Wêreld Gesondheidsorganisasie (WGO) beraam dat ten minste 75% van alle babas net baba formule melk (BFM) of BFM in kombinasie met moedersmelk in die eerste vier maande na geboorte kry. Die teenwoordigheid van die voortkomende patogeen Enterobacter sakazakii in BFM is al geassosieer met skaars maar noodlottige gevalle van neonatale infeksies en sterftes. Akkurate metodes word dus benodig vir die vinnige deteksie van E. sakazakii in voedsel. Die metodes wat huidiglik gebruik word vir die deteksie en identifikasie van hierdie mikroörganisme is onvoldoende, kontroversieël en teenstrydig. Die doel van hierdie studie was om die beste metode vir die deteksie van E. sakazakii te bepaal, na 'n evaluasie van die metodes wat huidiglik beskikbaar is. 'n Verdere doel was om 'n polimerase ketting reaksie (PKR) metode vir die deteksie van slegs lewensvatbare E. sakazakii selle te optimiseer deur gebruik te maak van die DNSbindende kleurstowwe, etidium mono-asied (EMA) en propidium mono-asied (PMA). Die Voedsel en Medisyne Administrasie (VMA) se metode vir E. sakazakii deteksie is gebruik om, ongeag van die kolonie kleur, 50 isolate vanuit BFM en 14 isolate vanuit die omgewing te kies. Hierdie isolate is geïdentifiseer deur die DNS volgorde van 'n 1.5 kilo-basis (kb) fragment van die 16S ribosomale DNS (rDNS) te bepaal en die Nationale Sentrum vir Biotegnologiese Informasie (NSBI) databasis te gebruik om die mees verwante spesie te bevestig. Sewe van die 50 (14%) BFM isolate en ses van die 14 (43%) omgewings isolate is geïdentifiseer as E. sakazakii. Die metodes wat geëvalueer is in terme van akkuraatheid vir deteksie en identifikasie van hierdie E. sakazakii isolate het PKR met ses verskillende spesie-spesifieke peiler pare soos beskryf in die literatuur, geel-pigment produksie op triptoon soja agar (TSA) en chromogeniese Druggan-Forsythe-Iversen (DFI) en Enterobacter sakazakii (ES) agars ingesluit. Die geskiktheid van die VMA metode is verlaag deur die lae sensitiwiteit, spesifisiteit en akkuraatheid (87%, 71% en 74% onderskeidelik) van geel pigment produksie vir E. sakazakii identifikasie. Chromogeniese DFI en ES agars was sensitief, spesifiek en akkuraat (100%, 98% en 98% onderskeidelik) vir die identifikasie van E. sakazakii. Die spesifisiteit van die PKR produkte het gewissel tussen 8% en 92%, en Esakf en Esakr is as die akkuraatste geëvalueerde peiler paar geidentifiseer. Die huidige VMA metode vir E. sakazakii deteksie vereis hersiening aangesien meer sensitiewe, spesifieke en akkurate deteksiemetodes voortdurend beskikbaar word. 'n Nuwe metode, gebaseer op die resultate van hierdie studie, word voorgestel vir die deteksie van E. sakazakii in voedsel- en omgewingsmonsters. Die voorgestelde metode vervang die kwekingsstap op violet rooi gal glukose agar (VRGGA) en TSA deur kweking op chromogeniese DFI of ES agars. Verder word die oksidase toets, geel pigment produksie en API biochemiese profiele van vermoeidelike E. sakazakii isolate vervang deur DNS volgorde bepaling en/of spesie-spesifieke PKR met die mees spesifieke peiler paar (Esakf and Esakf) vir die identifikasie en bevestiging van E. sakazakii. Die voorgestelde wysigings van die VMA metode sal die tydsduur van E. sakazakii identifikasie van 7 dae na 4 dae verminder, en behoort ook meer sensitief, spesifiek en akkuraat te wees vir die deteksie van E. sakazakii. 'n Nuwe PKR-gebaseerde metode wat tussen lewensvatbare en dooie E. sakazakii selle kan onderskei is in hierdie studie ontwikkel. Dit is bereik deur die onomkeerbare binding van bakteriële DNS aan lig-geaktiveerde EMA of PMA om die PKR amplifisering van dooie selle te voorkom. Konsentrasies van 50 en 100 μg.ml-1 PMA het PKR amplifikasie heeltemal geïnhibeer, terwyl geen inhibisie van lewensvatbare selle bespeur kon word nie. EMA was ook suksesvol in die voorkoming van die PKR amplifikasie van dooie selle, alhoewel daar ook 'n mate van DNS inhibisie was tydens die amplifikasie van lewensvatbare selle. PMA-PKR kan ook van nut wees vir die assessering van die doeltreffendheid van prosesseringstegnieke, en ook vir die waarneming van die weerstandigheid, oorlewingsstrategieë en stresresponse van E. sakazakii. Dit sal 'n belangrike stap wees in pogings om E. sakazakii van voedsel en voedsel produksieomgewings te elimineer.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2006. / The food and beverage industry generates large volumes of wastewater annually. The disposal of factory effluent from the fruit processing industry has always been a cause of concern to both the fruit processors and controlling bodies responsible for effluent management. Traditional disposal of wastewater into sewerage works has become undesirable due to its economical and environmental impacts. Therefore, on-site anaerobic treatment of wastewater has received considerable interest due to lower capital outlays and energy recovery possibilities. Thus, the aim of this study was to establish an operational treatment profile for an anaerobic pond system treating fruit-processing wastewater. The specific activity of the microbial populations was also monitored to determine the effect of the fruit processing seasons (peak and off-peak season). The biogas production potential at various temperatures was also assessed to determine the viability of methane recovery. The influence of the processing and environmental conditions on the ponds’ performance was established by monitoring various process parameters. The results showed that the chemical oxygen demand (COD) levels decreased during the off-peak season but the pond pH remained relatively stable between 6.0 and 6.4 during the entire year. Pond alkalinity was found to be dependent on the regular lime dosing to maintain the necessary alkalinity. The volatile fatty acid (VFA) concentrations indicated that the microbial populations of the pond were functioning well. However, a decrease in microbial activity and VFA concentrations were observed at the lower temperatures during the winter months. The temperature profile of the pond showed that the pond temperature was impacted by the fluctuations in the ambient air temperature. The general trend established by the operational treatment profile clearly showed the impact of the peak and off-peak season. The sludge activity of the anaerobic pond was evaluated to determine the effect of the apple-processing peak and off-peak season on the specific activity of the acidogenic and methanogenic populations within the sludge. An activity test using four different test media was used during the activity assays. Sludge samples were taken at four different sampling positions across the pond’s sludge bed. The sludge was also subjected to a biogas formation study, which was designed to simulate pond conditions on laboratory scale in order to evaluate the biogas production potential of the anaerobic pond. The cumulative biogas volume and total CH4 composition showed little or no difference between the four sludge sampling sites. A major difference was found between the activity of the microbial populations during the peak and off-peak seasons. The overall trend regarding the biogas production rate (SB) and the methane production rate (SM) values showed an increased activity during peak-season and a decreased activity during off-peak season. For the biogas formation test the highest incubation temperature (25°C) resulted in the most biogas being produced, followed by 18°C, and with 10°C resulting in the lowest biogas volume. The biogas formation tests indicated that microbial activity and therefore biogas production was dependent on especially favourable temperature conditions. The pond and activity of the microbial populations are therefore influenced by factors like environmental changes such as decreased air temperatures and substrate changes such as decreased COD concentrations during the off-peak season. This in turn influences the rate of biogas production as well as the methane production rate. The theoretical CH4 calculations and estimates based on the results obtained during the biogas formation tests indicated that CH4 recovery from the anaerobic pond would definitely be a worthwhile consideration. If it were assumed that the estimated CH4 volumes (based on only 15% of the pond volume for practical reasons) obtained could be applied as an energy source, the minimum yearly savings in coal usage would amount to about R 665 000. This study was valuable in evaluating the factors such as pond conditions, pond activity and air temperatures and the effect on the biogas production potential as well as more importantly, CH4 production for the purpose of energy recovery.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2007. / The distillery industry generates large volumes of heavily polluted wastewater and thus effective wastewater treatment is essential. It has been reported that a chemical oxygen demand (COD) reduction of more than 90% can be achieved when wine distillery wastewater (WDWW) is treated in an upflow anaerobic sludge blanket (UASB) reactor. The first objective of this study was to investigate UASB treatment of WDWW and to try to enhance the efficiency by using ozonation treatments. Secondly, the impact of grain distillery wastewater (GDWW) on UASB granules was determined. The third objective was to determine whether ozonation and enzymatic treatment combinations might improve the biodegradability of GDWW and thus make GDWW more amenable to UASB treatment. It was found that UASB treatment combined with ozonation improved the WDWW treatment efficiency. When diluted WDWW (chemical oxygen demand COD = 4 000 mg.L-1) was ozonated (dose = 47 mg.L-1) in a 50 L venturi circulating contactor system, the COD reduction was 7%. When WDWW was treated in a laboratory-scale UASB reactor (substrate pH = 7.0, COD = 4 000 mg.L-1 and organic loading rate (OLR) = 4.0 kg COD.m-3.d-1), the COD reduction was 92%. When the UASB treatment was combined with either pre- or postozonation, the COD reduction was 94 and 96%, respectively. When UASB treatment was combined with pre- and post-ozonation, a COD reduction of 98% was achieved. The activity of the UASB granules was also found to improve over time, despite the addition of the ozonation treatment. It has been reported that operational problems occur when GDWW is treated in an UASB reactor as a result of the encapsulation of the granules. This was confirmed when granules from a full-scale UASB treating WDWW became encapsulated in a layer after being exposed to GDWW (COD = 4 000 mg.L-1) for 24 d. The results showed that the lipid content of the granules increased from 1.25 to 60.35 mg lipid.g-1 granule over the 24 d exposure period. Therefore, granules exposed to GDWW were encapsulated in a lipid-rich layer and as a result the contact between the GDWW and microbial consortium in the granules was reduced. The operational problems found during the industrial UASB treatment of GDWW were ascribed to the encapsulation of the granules. Combinations of ozonation (dose = 1 476 mg.L-1) generated in a 2 L bubble column and enzymatic treatments (1% FogFreeTM (FF) dosage and 2 d incubation at 35°C) were found to improve the biodegradability of GDWW. This improvement was in terms of lipid reduction in GDWW, granule activity and visual appearance of the encapsulating layer of the granules. The highest lipid reduction (90%), highest granule activity, lowest lipid content of the granules (3.74 ± 0.10 mg.g-1 granule) and best visual appearance were achieved in ozonated GDWW treated with 1% FF, followed by just ozonation. The higher lipid reduction and subsequent higher granule activity were ascribed to the reduction in lipids which resulted in the fact that fewer lipids were available to encapsulate the granules. As a result of the lipid reduction, the granule activity improved and the GDWW was made more amenable to UASB treatment. This study proved that UASB treatment combined with ozonation led to an enhancement of the treatment efficiency of WDWW. It was also found that the cause of the operational problems during UASB treatment of GDWW was as a result of the granules being encapsulated in a lipid-rich layer. It was established that treating GDWW prior to UASB treatment improved the biodegradability of GDWW. The data from the study showed that high lipid reduction in the GDWW directly led to better granule activity, lower granule lipid content and a thinner encapsulating layer. Based on the data from this study, it is recommended that GDWW be ozonated prior to other treatments because it can be done inline and the costs would be lower than that of enzymatic treatments.

Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: This study focussed on the sensory effects of the main volatile compounds produced by Brettanomyces yeast causing spoilage in wine. This research firstly aimed to determine the detection thresholds of eight Brett-related spoilage compounds in wine. The second aim was to determine the sensory effect of the four most important Brett-related compounds when present individually in wine. The third aim was to determine the sensory effects of these four compounds when present in wine in a range of combinations, and to further investigate their effect on consumer liking. Finally, this project aimed to investigate the incidence of these compounds in a small range of South African wines. The sensory detection thresholds of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4- vinylphenol, 4-vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid were determined. Apart from 4-ethylcatechol, these values generally agreed well with recent literature where values determined in wine are available. However, the discrepancies highlighted the importance of the effect of the medium (wine) when determining sensory detection thresholds. The use of the median as alternative calculation method was also investigated, and it was found that this method gives more insightful results than the standard American Society of Testing Materials (ASTM E679-04) method. Four compounds, namely 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were profiled individually in wine using a trained sensory panel. It was found that all four compounds caused a suppression of the natural berry-like character in the wine, which induced a sick-sweet character. 4-ethylphenol contributed Elastoplast™ and leather aromas in the wine, both of which are commonly associated with Brettanomyces taint. 4-ethylguaiacol added a medicinal aroma to the wine, and 4-ethylcatechol and isovaleric acid were responsible for savoury and pungent aromas, respectively. 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol and isovaleric acid were also profiled in combination according to the central composite design. Several univariate and multivariate methods were applied to the dataset obtained. PARAFAC, a multiway method not widely utilized regarding sensory data, was applied to the data, the results of which were complementary to those obtained during univariate and multivariate analyses. It was found that there is a great deal of interaction between the four compounds profiled in terms of sensory effects. The most notable was the Elastoplast™ attribute, the intensity of which was affected by all four compounds. The pungent attribute was also affected by the 4-ethylphenol concentration. Consumer analysis revealed that some of the samples spiked with Brettanomyces-spoilage compounds were preferred to the unspiked (control sample). However, no further relationship could be found between consumer liking and either chemical composition or sensory profile. It is therefore speculated that consumer liking of Brettanomyces infected wine is driven by more complex sensory or socio-demographic factors. Finally, the concentration of 4-ethylphenol, 4-ethylguaiacol, 4-ethylcatechol, 4-vinylphenol, 4- vinylguaiacol, isovaleric acid, isobutyric acid and acetic acid was determined in a small set of South African wines, selected to contain a high proportion of wines spoiled by Brettanomyces. Significant correlations were found between 4-ethylphenol and 4-ethylguaiacol, as well as 4- ethylphenol and isovaleric acid. However, no correlation could be found between 4-ethylphenol and 4-ethylcatechol. It is speculated that this lack of relationship is due to the different precursor profiles present in the analysed wines. This study paved the way for future investigations on the sensory effects of Brettanomyces spoilage in Pinotage red wine. / AFRIKAANSE OPSOMMING: Hierdie studie het gefokus op die sensoriese invloed van die belangrikste vlugtige komponente wat deur die Brettanomyces gis geproduseer word en bederf veroorsaak in wyn. Eerstens is gefokus op die bepaling van die deteksiedrempelwaardes van agt Brett-verwante bederwende komponente. Die tweede doelwit was om die sensoriese invloed van vier van die mees belangrike Brett-komponente te bepaal wanneer hulle individueel in wyn voorkom. Die derde doelwit was om die sensoriese invloed van hierdie vier komponente te bepaal wanneer hulle in verskillende kombinasies in wyn voorkom, asook die effek daarvan op verbruikervoorkeur. Laastens is gepoog om die voorkoms van hierdie komponente in ‘n klein seleksie van Suid- Afrikaanse wyne te bepaal. Die sensoriese deteksiedrempelwaardes vir 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4- vinielfenol, 4-vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur is bepaal. Met die uitsondering van 4-etielcatechol het die waardes oor die algemeen goed ooreengestem met waardes wat onlangs in die wetenskaplike literatuur gepubliseer is. Die uitsonderings het egter die belangrikheid van die medium (wyn) gedurende die bepaling van sensoriese deteksiedrempelwaardes uitgelig. Die gebruik van die mediaan as ‘n alternatiewe berekeningsmetode is ook ondersoek en daar is gevind dat hierdie metode meer insiggewende resultate lewer as die standaard American Society of Testing Materials (ASTM E679-04) metode. Vier komponente naamlik 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is individueel in wyn geprofileer met behulp van ‘n opgeleide sensoriese paneel. Daar is gevind dat al vier die komponente die natuurlike bessiekarakter in die wyn onderdruk terwyl dit aanleiding gee tot ‘n onnatuurlike soet karakter. 4-etielfenol is gekenmerk aan Elastoplast™ en leeragtige aromas in die wyn en beide van hulle word algemeen geassosieer met Brettanomyces bederf. 4-etielguaiacol het ‘n medisinale aroma tot die wyn toegevoeg en 4- etielcatechol en isovaleraatsuur het respektiewelik souterige (“savoury”) en sterk (“pungent”) aromas tot gevolg gehad. 4-etielfenol, 4-etielguaiacol, 4-etielcatechol en isovaleraatsuur is ook in verskeie kombinasies geprofileer volgens die sentrale saamgestelde ontwerp (“central composite design”). Verskeie enkelveranderlike en meerveranderlike statistiese analisemetodes is ook op die datastel uitgevoer. PARAFAC, ‘n meerrigtingsmetode wat nie normaalweg vir sensoriese analise data gebruik word nie, is ook uitgevoer op die data en die resultate was komplimentêr tot die van die enkelveranderlike en meerveranderlike analisemetodes. Daar is gevind dat, met betrekking tot sensoriese effekte, daar noemenswaardige interaksie tussen die vier komponente plaasvind. Die mees opmerklike hiervan was die Elastoplast™ aroma, waarvan die intensiteit deur al vier die ander komponente geaffekteer is. Verder is die sterk (“pungent”) aroma beïnvloed deur die 4-etielfenol konsentrasie. Verbruikersvoorkeur-analise het aangedui dat sommige van die monsters waarby Brettanomyces bederwende komponente gevoeg is, verkies word bó die kontrole-wyn. Daar kon egter geen verdere verband gevind word tussen die verbruiker se voorkeur en, nog die chemise komposisie of sensoriese profiele, van die wyn nie. Daar kan dus gespekuleer word dat verbruiker voorkeur van Brettanomyces bederfde wyn gedryf word deur meer komplekse en sosio-demografiese faktore. Laastens is die konsentrasies van 4-etielfenol, 4-etielguaiacol, 4-etielcatechol, 4-vinielfenol, 4- vinielguaiacol, isovaleraatsuur, isobuteraatsuur en asynsuur in ‘n seleksie van Suid-Afrikaanse wyne bepaal. Dié wyne is spesifiek so gekies sodat ‘n aansienlike aantal van hulle met Brettanomyces bederf was. Betekenisvolle korrelasies is gevind tussen 4-etielfenol and 4- etielguaiacol, sowel as 4-etielfenol en isovaleraatsuur. Daar is egter geen korrelasie tussen 4- etielfenol and 4-etielcatechol gevind nie. Daar word vermoed dat hierdie gebrek aan korrelasie te wyte is aan die voorloperkomponent profiele teenwoordig in die wyne. Hierdie studie het die weg gebaan vir verdere ondersoeke na die sensoriese effekte van Brettanomyces bederf in Pinotage rooi wyn.

Thesis (MSc Food Sc )--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The South African apple juice processing industry is growing rapidly and during the harvesting season the wastewater volumes and organic loads increase significantly with a considerable environmental impact. These larger apple juice processing wastewater (AJPWW) volumes and chemical oxygen demand (COD) loads subsequently lead to faster increases in the organic loading rate (OLR) of an upflow anaerobic sludge bed (UASB) wastewater treatment system and it is necessary to know if the treatment system can handle such drastic increases over short periods. The objective of the study were to evaluate the efficiency of the UASB process in the treatment of an AJPWW; to determine what effect a substrate viscosity increase, based on a pectin calcium gel has on the performance of an UASB system, and to determine what impact ozonation has on the pectin content, gelformation ability and biodegradability of the AJPWW. The ability of the UASB to maintain stability during the apple-processing season was investigated by increasing the OLR from 2.9 to over 14.0 kg COD.m-3.d-1 in 131 days. During this time the COD removal remained constant at 85%, while the pH and alkalinity remained at levels indicative of good reactor stability. It was thus concluded that the UASB reactor could operate successfully during the apple-harvesting season when wastewater volumes and organic loads increase significantly. In the study it was found that the viscosity of the AJPWW, containing 750 mq.L-1 pectin, increased from 8.5 to 47.0 cps after a 312 rnq.L-1 Ca2 + addition. This increased viscosity substrate was then fed to an UASB reactor at an OLR of 15.0 kg COD.m-3.d-1. During a 12 day increased viscosity (47 cps) feeding stage the COD removal decreased from 94 to 11%, while the reactor pH decreased from 7.5 to 4.9. During this period, pectin accumulated in the UASB and led to biomass washout and rapid UASB failure. The possible elimination of pectin by ozonation was thus investigated, and a 77% decrease in pectin content and 76% decrease in gel formation ability occurred after ozonation. The effect of pre- and post-ozonation on the efficiency of the UASB system was subsequently investigated. It was found that a 10 min pre-ozonation decreased the AJPWW COD by 19% and the total suspended content by 36%, while the soluble portion of the total COD was increased from 81.7 to 92.4%. This increase in soluble COD content should lead to increased wastewater biodegradability. The ozonated AJPWW was then used to replaced the raw non-ozonated AJPWW as reactor feed. Results showed that the COD removal increased from 78 to 90% within 24 h of starting with the ozonated feed. It was also found that the reactor stability improved after AJPWW pre-ozonation as an OLR increase from 10.0 to 16.6 kg COD.m-3.d-1 in 23 days did not detrimentally influence the stability of the reactor. This reactor effluent (COD = 465 rnq.L-1) was then post-ozonated which resulted in 64.8% COD and 79.0% colour reductions. The final effluent had a COD of 180 rnq.L-1 (98% reduction). The ability of the ozonation/digestion system as described in this study to degrade AJPWW at a higher OLR is of value to the apple industry, as it may lead to larger organic pollutant removals and thus a more effiecient treatment system. Increased reactor performance will directly improve the quality of the final wastewater produced, which in turn will have a significant impact on the treatment ability of the South African apple processing industry currently limited by the production of large wastewater volumes. / AFRIKAANSE OPSOMMING: Gedurende die oesseisoen word groot volumes afvalwater met 'n hoe organiese lading in die vinnig groeiende Suid-Afrikaanse appelsapprosesseringsbedryf geproduseer. Dit het 'n groot impak op die omgewing. Die groter volumes appelsapprosesseringsafvalwater (ASPAW) met 'n hoë organiese lading het 'n vinniger verhoging in organiese ladingstempo's (OLT) van 'n UASB-waterbehandelingstelsel tot gevolg. Daarom is dit belangrik om te weet of die stelsel die drastiese verhoging oor kort tydperke kan hanteer. Die doel van hierdie studie was die evaluering van die effektiwiteit van die UASB-proses in die behandeling van ASPAW; om te bepaal watter effek 'n substraatviskositeitsverhoging, gebaseer op 'n pektien-kalsium-jel, op die doeltreffendheid van 'n UASB-stelsel het; en om te bepaal watter impak osonering op die pektieninhoud, jelvormingsvermoe en bioafbreekbaarheid van ASPAW het. Die vermoe van die UASB om stabiliteit te handhaaf gedurende die appelsapprosesseringseisoen is ondersoek deur die OLT van 2,9 tot bo 14,0 kg CSB.m-3.d-1 te verhoog oor 131 dae. Gedurende hierdie tyd het die chemiese suurstofbehoefte- (CSB-) verwydering konstant gebly by 85%, terwyl die pH en alkaliniteit ook op vlakke aanduidend van goeie reaktorstabiliteit gebly het. Daar is sodoende bewys dat die UASB-reaktor suksesvol kan presteer tydens die appelsapprosesseringseisoen, wanneer daar 'n beduidende verhoging in OLT plaasvind. In die studie is daar gevind dat die viskositeit van die ASPAW, wat 750 mq.L-1 pektien bevat, van 8,5 tot 47,0 cps toeneem na die byvoeging van 312 rnq.L-1 Ca2+. Hierdie verhoogde vikositeitsubstraat is tot die UASB-reaktor toegevoeg teen 'n OLT van 15,0 kg CSB.m-1.d-1. Gedurende 'n 12-dae toevoer van verhoogde viskositeit (47 cps), het die CSB-verwydering van die reaktor afgeneem van 94% na 11%, terwyl die pH gedaal het van 7,5 na 4,9. Gedurende hierdie tydperk het pektien in die UASB geakkumuleer, wat gelei het tot die uitspoel van biomassa en vinnige UASB-reaktormislukking. Die moontlike eliminasie van pektien, deur osonering, is daarom ondersoek. 'n Verlaging van 77% in pektieninhoud en 76% in jelvormingsvermoe het na osonering plaasgevind. Die effek van pre- en post-osonering op die effektiwiteit van 'n UASB-stelsel is gevolglik ondersoek. Daar is gevind dat 'n 10 minute pre-osonering die CSB van die ASPAW met 19% verlaag en die totale inhoud van gesuspendeerde vaste stowwe met 36% verlaag, terwyl die oplosbare gedeelte van die totale CSB van 81,7% tot 92,4% gestyg het. Die verhoging in oplosbare CSB-inhoud behoort tot verhoogde bioafbreekbaarheid van ASPAW te lei. Die geosoneerde ASPAW is gebruik om die rou, ongeosoneerde ASPAW as reaktorsubstraat te vervang. Die resultate het getoon dat die CSB-verwydering verhoog het van 78% na 90% na 'n 24-uur toevoer van geosoneerde substraat. Daar is ook gevind dat die reaktorstabiliteit toegeneem het na ASPAW osoneering, aangesien 'n OLT-verhoging van 10,0 na 16,6 kg.CSB.m-3.d-1 in 23 dae nie die stabiliteit van die reaktor nadelig beinvloed het nie. Hierdie reaktoruitvloeisel (CSB = 465 rnq.L-1) is hierna gepost-osoneer, wat 'n 64,8% CSB- en 79,0% kleurverlaging tot gevolg gehad. Die finale uitvloeisel het 'n CBS-inhoud van 180 rnq.L-1 gehad (98,1% verwydering). Die vermoe van die osonering-/verteringstelsel om ASPAW te degradeer teen 'n hoër OLT, soos beskryf in hierdie studie, is van waarde tot die appelsapprosesseringsbedryf, aangesien dit tot groter organiese afvalstofverwydering kan lei en dus 'n meer effektiewe behandelingstelsel tot gevolg kan hê. Verhoogde reaktordoeltreffendheid sal 'n direkte verbetering tot gevolg hê in die gehalte van die finale afvalwater wat geproduseer word, wat op sy beurt 'n beduidende impak sal hê op die behandelingsvermoe van die appelsapprosesseringsbedryf, wat tans beperk word deur die produksie van groot volumes afvalwater.