Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2005. / Antimutagenic activity of aqueous extracts of fermented and unfermented Cyclopia spp., i.e. C. intermedia, C. subternata, C. genistoides and C. sessiliflora against metabolically activated aflatoxin B1 (AFB1) in the Salmonella mutagenicity assay with tester strain TA100, was compared to that of fermented and unfermented Aspalathus linearis (rooibos) and Camellia sinensis (black, oolong and green) teas. Possible mechanisms involved in in vitro antimutagenic activity of these teas were investigated, i.e. the stabilising effect of the unfermented Cyclopia spp., unfermented rooibos and green tea on rat liver cytochrome P450 in the S9 fraction from Aroclor 1254 treated rats and their modulation of aniline-induced Type II difference spectra in the microsomal fraction. Inhibition of lipid peroxidation in rat liver S9, by the teas, was assessed to determine whether protection against lipid peroxidation may play a role in cytochrome P450 stability in vitro. Correlation of the antimutagenic activity of the teas with their stabilising effect on cytochrome P450 and inhibition of lipid peroxidation, provided insight into possibly related mechanisms. Antimutagenic activity correlated weakly with a decreased stabilising effect of the teas on cytochrome P450 (r = 0.411, P = 0.013) and the inhibition of lipid peroxidation (r = 0.475, P = 0.003). Decreased stability of cytochrome P450 was associated with substantial lipid peroxidation occurring in rat liver S9. Effective inhibition of lipid peroxidation and stabilising of cytochrome P450 in S9 was evident in the presence of the teas, but no correlation (r = 0.018, P = 0.915) existed for the effect of unfermented teas on cytochrome P450 stability with inhibition of lipid peroxidation. Black tea exhibited the highest protection against AFB1-induced mutagenesis and fermented C. intermedia offered the least protection. “Fermentation” resulted in increased antimutagenic activity of Camellia sinensis and rooibos teas, while the antimutagenic activity of Cyclopia spp. decreased with fermentation except for C. genistoides. Unfermented teas significantly (P < 0.05) stabilised cytochrome P450, with rooibos more effective (P < 0.05) than green tea, but similar (P < 0.05) to Cyclopia spp. Green tea demonstrated the highest inhibition of lipid peroxidation, while the inhibition exerted by rooibos was similar (P > 0.05) to unfermented Cyclopia spp., except for C. genistoides exhibiting the least inhibition. Total polyphenol, flavanol and flavonol/flavone contents of the respective teas were correlated with activity in terms of antimutagenicity, stabilising of cytochrome P450 and inhibition of lipid peroxidation. Antimutagenic activity of Cyclopia spp. correlated with its total polyphenol (r = 0.805, P < 0.0001) and flavanol (r = 0.653, P < 0.0001) contents, while a weak negative correlation (r = -0.456, P = 0.026) was observed for the inhibition of lipid peroxidation by unfermented Cyclopia spp. with the flavonol/flavone content. Antimutagenicity of Cyclopia spp. correlated weakly (r = 0.363, P = 0.012) with its hesperidin content. Antimutagenic activity of rooibos tea correlated moderately (r = 0.751, P < 0.005) with its flavonol/flavone content and specifically the flavones orientin (r = 0.674, P < 0.023) and iso-orientin (r = 0.728, P < 0.011). A strong negative correlation (r = -0.918, P < 0.0001) of antimutagenicity of rooibos with its aspalathin content was observed. Antimutagenic activity of Camellia sinensis teas did not correlate with their total polyphenol, flavanol or flavonol/flavone contents. The flavanol content of green tea showed a good, but marginal (P < 0.1) correlation (r = 0.824, P = 0.086) with decreased cytochrome P450 stability. The modulation of aniline-induced Type II binding to microsomal cytochrome P450 by green tea differed significantly (P < 0.05) from the modulation exhibited by rooibos and Cyclopia spp. Flavonoid glycosylation appeared to influence antimutagenic activity, stabilising of cytochrome P450 and modulation of substrate binding of selected phenolic compounds. The present study indicates that rooibos and Cyclopia spp. have in vitro antimutagenic activity against AFB1, suggesting that consumption of these two herbal teas may have beneficial health effects. It is also suggested that stabilising of cytochrome P450 by tea, and interaction of tea constituents with cytochrome P450, may influence their in vitro antimutagenic activity.

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2005. / It is estimated by the World Health Organisation (WHO) that thousands of millions of cases of foodborne diseases occur world–wide every year. Enterobacter sakazakii is a member of the family Enterobacteriaceae and has been identified as an occasional contaminant of powdered infant formula milk (IFM). Enterobacter sakazakii is an opportunistic emerging pathogen and has the ability to cause a severe form of neonatal meningitis. This organism was referred to as “yellow pigmented Enterobacter cloacae” until 1980 after which it was renamed as E. sakazakii. The current method for the detection of E. sakazakii is very time consuming and includes pre–enrichment, enrichment in Enterobacteriaceae enrichment broth, subsequent plating on violet red bile glucose agar and subculturing on tryptone soy agar. In this study a polymerase chain reaction (PCR) method was developed for the identification of the presence of E. sakazakii in infant food products. A part of the 16S ribosomal RNA (rRNA) gene from E. sakazakii was amplified using the primer pair Esak2 and Esak3. An internal amplification control (IAC) was constructed as part of the PCR detection method. The 850 base pair (bp) E. sakazakii PCR product was digested with AluI and the two fragments containing the primer binding sites were ligated, resulting in a 240 bp IAC. During this study a positive band for both the target DNA (850 bp) and the IAC (240 bp) was simultaneously observed when the IAC was added to the PCR mixture at a concentration of 0.72 pg.ml-1. Four of 22 South African food products tested positive for the presence of E. sakazakii, using both the PCR and recommended culturing methods. The PCR method was used successfully for the detection of E. sakazakii within three days and thus provides a possible alternative and improvement on the recommended current culturing methods. Other microorganisms present in the products tested included Escherichia coli, Klebsiella pneumoniae, Raoultella terrigena (“Klebsiella terrigena”) and Chryseomonas luteola. Since E. sakazakii is usually present in low numbers in food products, it is possible that these few cells are unevenly distributed in the products, making it important to take multiple samples when evaluating IFM and thereby ensuring that even low numbers of this pathogen are detected.

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The "classical" propionibacteria are used in a variety of natural dairy fermentations where they produce natural preservatives (propionic and acetic acids and bacteriocins) and large amounts of vitamin B12. The extracellular polysaccharide (ECP) producing ability of these bacteria also make them of special interest to the food and waste water management industries as the ECP has been illustrated to playa role in the initial granule formation in upflow anaerobic bioreactor systems. There is little known on the ECP production by propionibacteria and in this study different environmental conditions that influence ECP production were studied. Nineteen different Propionibacterium strains were examined in terms of ECP production and Propionibacterium strain 278 was identified as the best ECP producer. Further studies were only done on this strain because of its high ECP production and because it was originally isolated from an anaerobic digester. The influence of temperature, pH and sucrose concentration was determined through the measurement of ECP production and medium viscosity. It was found that more ECP was produced at temperatures lower than the optimum for growth with the optimum being between 22° and 25°C. Lower initial pH conditions of the growth medium (below pH 7.0) were found to inhibit ECP production and the influence when the initial pH values were between 7.0 and 8.5, was not significant. A higher carbon: nitrogen ratio, when 8% sucrose was added, was also found to enhance the ECP production. The upflow anaerobic sludge bed (UASB) bioreactor process depends on the upward movement of soluble matter through a blanket of active methanogenic granular sludge. The long start-up times as a result of the slow granulation process, as well as the need for a speedy replacement of granules once they have been washed out of the system, are limitations that restrict the general application of this excellent waste water treatment technology. Full exploitation of this biomass immobilisation technique can thus not be realised until the granule formation conditions are defined and optimised. The precise nature of the mechanisms involved in the formation of granules and the reason for their stability, is still not fully understood. It was hypothised by Britz et al. in 1999 that, through the implementation of environmental 'stress' conditions, a shift in the population dynamics of the anaerobic community can be obtained. This results in a concurrent increase in ECP formation that appears to enhance aggregate formation. In the second study it was found that, when 'stress' conditions were applied to already formed granules, the Gram-positive lactate-utilising acidogenic population gained an advantage and more propionic acid producing bacteria were present. The propionic and acetic acid concentrations were also found to increase, and concurrently, a decrease in the growth medium pH occurred. This confirms part of the granulation hypothesis that, when granules are 'stressed', the acidogenic population dynamics change and the lactate-utilising population responds to the gradual decrease in pH and the more acid-tolerant propionic acid producing bacteria gain a competitive advantage resulting in the increase in the propionic acid concentration. When propionibacteria were added to raw sludge during the granule production process, the granules were found to be more active than when nopropionibacteria had been added. This was probably due to the ECP formation by the propionibacteria that enhances the aggregation of the granules. Enhanced granulation was thus found in the batch systems with the fatty acids formed in correlation with the model for granulation. A good correlation was evident between the hypothesis and the experimental data and the hypothesis was partially verified in this study. / AFRIKAANSE OPSOMMING: Die "klassieke" propionibakterieë word in 'n verskeidenheid van natuurlike suiwel fermantasies gebruik waarin hulle verantwoordelik in vir die produksie van natuurlike voedsel preserveermiddels (propioonsuur, asynsuur en bakteriosiene) en groot hoeveelhede vitamiene B12. Die Ekstra Sellulêre Pollisakkaried (ESP) produserende eienskap van hierdie groep bakterieë maak hulle ook van belang in die voedsel en afvoerwater beheer industrieë, aangesien gevind is dat ESP 'n rol speel in die aanvanklike granule formasie in anaerobiese bioreaktor sisteme. Daar is nog baie min bekend oor die ESP produksie van propionibakterieë en in hierdie studie is verskeie omgewings faktore wat die ESP produksie beïnvloed, bestudeer. Negentien verskillende Propionibakterium stamme was bestudeer in terme van ESP produksie en Propionibakterium stam 278 was geïdentifiseer as die stam wat die meeste ESP produseer. Verdere studies was op hierdie stam gedoen na aanleiding van sy hoë ESP produksie en omdat dit oorspronklik uit 'n anaerobiese verteerder geisoleer is. Die invloed van termperatuur, pH en sukrose konsentrasie was bepaal deur die meting van die ESP produksie en die medium viskositeit. Dit was gevind dat meer ESP geproduseer was by temperature laer as die optimum vir groei, met die optimum temperatuur tussen 22° en 25°C. Dit is ook gevind dat laer aanvangs groei-medium pH (laer as pH 7.0), ESP produksie inhibeer. Die invloed van die aanvangs groei-medium pH tussen 7.0 en 8.5 was egter nie betekenisvol nie. Dit is ook gevind dat 'n hoër koolstof tot stikstof verhouding, verkry deur die byvoeging van 8% sukrose, die ESP produksie verhoog. Die "upflow anaerobic sludge blanket" (UASB) proses vind plaas as gevolg van die opwaarste beweging van opgeloste organiese materiaal deur 'n granule bed van aktiewe metanogeniese granulêre slyk. Die lang 'start-up' tye as gevolg van die stadige granulasie proses, en die nodigheid om 'n vinnige verplasing van granules te hê nadat dit uit die sisteem gewas is, is beperkings wat die algemene toepassing van hierdie fantastiese afvoerwater tegnologie, strem. Volle implementering van hierdie biomassa immobilisereings tegniek kan dus nie plaasvind voordat die granule formasie gedefinieer en geoptimiseer is nie. Die presiese eienskappe van die meganismes betrokke en die formasie van die granules en die rede vir hul stabiliteit word egter nog nie ten volle verstaan nie. Volgens 'n hipotese deur Britz et al. (1999), vind 'n verskuiwing in die populasie dinamika van die anaerobiese gemeenskap plaas tydens die implementasie van omgewings 'stress' toestande. Die resultaat is 'n verhoging in ESP produksie en 'n gevolglike verbetering in die granulasie proses. In die tweede studie was dit gevind dat, wanneer 'stress' toestande op die reeds gevormde granulasie toegepas word, die Gram-positiewe laktaat-benuttende asetogeniese populasie voordeel geniet en meer propioonsuur produserende bakterieë was teenwoordig. Die propioonsuur en asynsuur konsentrasies het ook verhoog en met 'n gevolglike daling in die groei-medium se pH. Dit bevestig 'n gedeelte van die hipotese dat, wanneer die granules onder 'stress' geplaas word, die asetogeniese populasie dinamika verander en die laktaat-benuttende populasie reageer tot die gedeeltelike afname in pH. Die meer suur-tolerante propioonsuur produserende bakterieë verkry 'n kompeterende voordeel en gevolglik is daar 'n verhoging in propioonsuur konsentrasie. Propionibakterieë was gevoeg by die onbehandelde slyk gedurende die granule produksie proses, en daar is gevind dat meer aktiewe granules gevorm word as andersins. Dit is moontlik as gevolg van die die ESP produksie van propionibakterieë wat die granulasie versnel het. Verbeterde granulasie was dus verkry in die sisteme waar propionibakterieë bygevoeg is. Vetsuur analises het gedui dat die gevormde vetsure ook in korrelasie was met die model van granulasie. Goeie korrelasie was dus verkry tussen die hipotese en die eksperimentele data en die hipotese is gedeeltelik bewys in hierdie studie.

Thesis (MSc Food Sc )--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The potential use of the upflow anaerobic sludge blanket (UASB) bioreactor is limited by the extended start-up periods due to the time-consuming granulation process and the fact that seeding inoculum is not freely available in most developing countries like South Africa. The mass cultivation of granules would provide the waste water treatment industry with suitable seeding inoculum and, therefore, an efficient waste water treatment option would be more easily available. By applying 'stress' conditions on a bioreactor system seeded with raw anaerobic sludge, the population dynamics of the anaerobic community change and the acidogens start to produce extracellular polymers, which in turn enhance the granulation process by providing a matrix for the bacterial cells to adhere to. These "environmental stress" conditions include changes in the C:P:N ratio's. The aim of this study was, therefore, to assess the impact of different carbon and nitrogen sources on the enhancement of granulation in a batch system, and to determine the best preservation technique in terms of retainment of activity. It was found that the carbon source and concentration had a significant influence on batch granule enhancement. Low concentrations (2.g.l ̄ ¹) of glucose gave the best granule enhancement over a 14 day incubation period. Fruit cocktail effluent was found to be a cheap and effective carbon source for batch granule cultivation. It was found that different nitrogen sources did not have the same impact on granule enhancement, however, urea, at all concentrations tested, gave the best granule enhancement. A major problem encountered during the study was the standardisation of the inoculum. Significant granule enhancement comparisons between the different carbon sources were impeded by the lack of a suitable and reliable form of sludge standardisation. Future research needs to address this problem of the standardisation of the sludge inoculum as this would lead to more kinetically comparable results. Mass granule culturing will require granule preservation without risking the loss of activity. In the second study, six different preservation techniques and storage periods were evaluated in terms of the retainment of activity. These involved freeze-drying, vacuum freeze-drying, vacuum-drying, freezing, cold storage and room temperature preservation. Activity testing was used for comparing the efficiency of the different preservation techniques in terms of the tempo of biogas and methane production. Freeze-drying the granules, with storage for up to 90 days was found to give the best retainment of activity, followed by vacuum freeze-drying. The room temperature preserved samples showed a sudden increase in activity by day 120, which could possibly be explained by cell hydrolysis of the granules after day 90. The highest activity was achieved after 10 h of incubation, and it was, therefore, suggested that activity testing for evaluation purposes should use an incubation time of only 10 h. Furthermore, only the basic test medium with added glucose should be used for activity testing as it was observed that the addition of lactate and acetic acid played no decisive role in determining the level of activity of the granules. This study recommends the use of low concentrations of glucose for optimum granule enhancement during the mass cultivation of granules, and the addition of low concentrations of lactate to ensure a stable system with no acidification. It is also advisable to use a standardised sludge inoculum, as this will allow more efficient comparisons. Freeze-drying is recommended as preservationtechnique as this technique showed the best retainment of activity. A storage period of 90 days is, however, too short to be of much use for the industry. This will have to be investigated, together with the phenomenon of increased activity after 90 days as shown by the room temperature preserved granules. / AFRIKAANSE OPSOMMING: Die potensiële gebruik van die "uptflow anaerobic sludge blanket" (UASB) bioreaktor word beperk deur verlengde aansitprosedure as gevolg van die tydsame granulasieproses en die feit dat geskikte inokulums nie vrylik beskikbaar is in die meeste ontwikkelende lande, bv. Suid-Afrika nie. Die massa-kweking van granules sal die afvalwater-industrie voorsien van 'n geskikte inokulum, en sodoende 'n effektiewe opsie vir die behandeling van afvalwater beskikbaar stel. Deur die aanwending van "stres" toestande op 'n reaktor, wat geinokuleer is met rou anaerobe slyk, vind daar 'n verandering in die samestelling van die anaerobe populasie plaas. Die laktaat-benuttende asidogene begin om ekstrasellulêre polisakkariede te produseer wat die granulasieproses versnel deur 'n matriks te voorsien waaraan die bakteriële selle kan heg. Hierdie "omgewings stres" toestande sluit veranderinge in die C:P:N verhoudings in. Die doel van hierdie studie was om die invloed van verskillende koolstof- en stikstofbronne op die vermeerdering van granules te bepaal, asook om die beste preserveringstegniek in terme van die behoud van aktiwiteit te bepaal. Daar is gevind dat die koolstofbron en konsentrasie 'n betekenisvolle invloed op granule-vermeerdering het. Lae konsentrasies glukose (2 g.I ̄ ¹) het tot die grootste vermeerdering in granules oor 'n 14 dae inkubasieperiode gelei. Vrugtekelkie-afvalwater is geidentifiseer as 'n goedkoop en effektiewe koolstofbron wat ook gebruik kan word vir die kweking van granules. Voorts is gevind dat die stikstofbron en konsentrasie nie so 'n groot invloed op granule-vermeerdering het nie. Urea het nietemin die beste granule-vermeerdering vir al die konsentrasies wat getoets is, gegee. Standaardisasie van die inokulum was 'n groot probleem gedurende die studie. Betekenisvolle vergelykings tussen die granule-vermeerderings verkry met die verskeie groeimedia is bemoeilik deur die afwesigheid van 'n geskikte en betroubare standaardisasie-metode. Toekomstige navorsing moet hierdie probleem aanspreek aangesien dit sal lei tot meer kineties vergelykbare resultate. Massa-kweking van granule sal 'n metode van granule-preservering vereis sonder enige verlies van aktiwiteit. In die tweede studie is ses verskillende preserverings-tegnieke en opbergings-periodes in terme van die behoud van aktiwiteit geëvalueer. Die tegnieke sluit in: vriesdroging; vakuum-vriesdroging; vakuumdroging; bevriesing; koelopberging en kamertemperatuur-preservering. Aktiwiteitstoetsing is gebruik vir die vergelyking van die effektiwiteit tussen die verskillende preserverings-tegnieke in terme van die tempo van biogas- en metaanproduksie. Die granules wat met behulp van die vriesdroogtegniek gepreserveer is, het die beste behoud van aktiwiteit getoon, gevolg deur die vakuum-gevriesdroogde granules. Die monsters wat by kamertemperatuur gepreserveer is, het 'n skielike toename in aktiwiteit na 120 dae van opberging getoon en 'n moontlike verklaring vir hierdie verskynsel kan sel-hidrolise van die granules na 90 dae van opberging wees. Die meeste aktiwiteit is behaal na 'n 10 h inkubasietyd, en dus word hierdie inkubasietyd aanbeveel indien aktiwiteitstoetse vir evaluerings-doeleindes gedoen word. Verder word aanbeveel dat slegs die glukose-verrykte basiese toetsmedia vir aktiwiteitstoetsing gebruik word aangesien die byvoeging van laktaat en asynsuur geen noemenswaardige rol speel in die bepaling van die vlak van aktiwiteit van die granules nie. Hierdie studie beveel die gebruik van lae glukosekonsentrasies aan vir optimale vermeerdering van granules tydens die massakweking daarvan, asook die byvoeging van lae konsentrasies laktaat om 'n stabiele sisteem met geen versuring te verseker. Die gebruik van 'n gestandaardiseerde slyk-inokulum word sterk aanbeveel aangesien dit meer vergelykbare resultate lewer. Vriesdroging (as preserveringstegniek) het die beste behoud van aktiwiteit in die granules getoon en word dus as preserveringstegniek aanbeveel. 'n Opbergingsperiode van 90 dae is egter te kort om van veel waarde vir die industrie te wees. Hierdie probleem, asook die verskynsel van 'n verhoging in aktiwiteit na 90 dae van die granules wat by kamertemperatuur gepreserveer is, moet verder ondersoek word.

Thesis (MSc Food Sc )--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The rapid urbanisation of the African population has led to the establishment of large low-income communities in and around almost every major town and city in South Africa. Several factors prevent these people from producing or obtaining their traditional fermented milk drink, Maas (Amasi), often resulting in the occurrence of malnutrition in low-income urban African communities. A product with the potential to satisfy the demand for a fermented milk product is Kefir. Kefir, a self-carbonated fermented milk, is commonly manufactured by fermenting unpasteurised or pasteurised milk with re-usable Kefir grains. These Kefir grains consist of a combination of mainly lactic acid bacteria and yeasts. Neither Kefir, nor Kefir grains are as yet marketed in South Africa, thus creating an excellent opportunity to launch these products locally. It is often difficult for the low-income communities to obtain high quality unpasteurised or pasteurised milk, resulting in a serious health risk. The inhibitory activity of Kefir towards certain spoilage and pathogenic microorganisms was, therefore, studied. Strains of Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes and Clostridium tyrobutyricum were inoculated (10 ³ - 10 ⁴ cfu.ml⁻¹ ) into pasteurised milk together with Kefir grains (18 gram per litre) and incubated at 25°C. Uninoculated milk samples and milk samples inoculated only with test organisms served as controls. Growth of all the test organisms were inhibited substantially (>-99.9%) in Kefir over the 30 h incubation period and substantial reductions in microbial log cycles were observed for many of the organisms. This coincided with a steep decrease in pH (6.57 - 4.06) and increase in titratabie acidity (0.20 - 0.72%). If Kefir is eventually marketed to low-income urban African consumers, it will have to compete with Maas and, therefore, comparative sensory testing of Kefir and Maas was conducted. The differences in the sensory properties of Kefir, 'laboratory' Maas (representing traditional Maas) and commercial Maas (containing thickener, colourants and flavourants) were determined by a trained panel. These characteristics were identified as "yeasty" and "cowy" tastes (p < 0.05), "effervescence" (p < 0.01), as well as "sourness," "creaminess" and "smoothness" (p < 0.001). The effect of different incubation temperatures (25°, 30° and 35°C) on the Kefir sensory properties was studied to simulate the effect of the large temperature variations that would be found in the dwellings of low-income African urbanites. The "sourness" and "creaminess" of the Kefir was found to increase with increase in incubation temperature but no strong off-flavours were found to develop. Sensory preference testing was conducted by consumer panels consisting of panellists of different ages and population groups to indicate whether the specific panels significantly prefer Kefir, commercial Maas or laboratory Maas. It was found that commercial Maas was significantly (p < 0.001) preferred to Kefir by young African urbanites. Adult Africans, who presumably still have traditional taste preferences, however, equally (p > 0.05) preferred Kefir and laboratory Maas, identifying this segment of the African population as the appropriate starting target market for Kefir. Kefir and laboratory Maas were also tested for preference by a wider panel consisting of people (aged between 18 and 25) representing the different population groups in South Africa. Kefir and laboratory Maas were preferred equally (p > 0.05) by all the groups. Several arguments supporting Kefir marketing to the low-income urban African population of South Africa have been identified. These include: Kefir's ease of preparation; the re-usability of Kefir grains and subsequent affordability; good packaging, distribution and storage possibilities; Kefir's acceptability by lactoseintolerant individuals; high nutritional value; the inhibitory activity of Kefir against potential spoilage and pathogenic organisms and subsequent enhanced safety and keeping ability; and Kefir's acceptable refreshing taste. / AFRIKAANSE OPSOMMING: Die toenemende verstedeliking van Swart Suid-Afrikaners het gelei tot die vestiging van groot lae-inkomste gemeenskappe in en om die meeste groot dorpe en stede. Verskeie faktore verhoed dat hierdie gemeenskappe hul tradisionele gefermenteerde melk, naamlik Maas (Amasi), self kan maak of koop. Dit lei dikwels tot wanvoeding onder lae-inkomste stedelike Swart verbruikers. Kefir het die potensiaal om te voorsien in die vraag na 'n gefermenteerde melk produk in lae inkomste stedelike Swart gemeenskappe. Kefir is 'n selfgekarboneerde, gefermenteerde melk wat vervaarding word deur die fermentasie van ongepasteuriseerde of gepasteuriseerde melk met herbruikbare Kefirkorrels. Hierdie Kefirkorrels bestaan uit 'n kombinasie van hoofsaaklik melksuurbakterieë en giste. Kefir en Kefirkorrels word glad nie in Suid-Afrika bemark nie, en bied 'n fantastiese geleentheid om hierdie produkte plaaslik bekend te stel. Dit is dikwels moeilik om hoë kwaliteit ongepasteuriseerde of gepasteuriseerde melk in lae-inkomste gemeenskappe te verkry. Die risiko om siektes deur die verbruik van hierdie melk op te doen, bestaan dus. Om hierdie rede is die inhiberende effek van Kefir teenoor spesifieke bederf- en patogeniese bakterieë bestudeer. Rasse van Escherichia coli, Staphylococcus aureus, Bacillus cereus, Usteria monocytogenes en Clostridium tyrobutyricum is geïnokuleer (10 ³ - 10 ⁴ cfu.ml⁻¹) in gepasteuriseerde melk tesame met Kefirkorrels (18 gram per liter) en geïnkubeer by 25°C. Melkmonsters wat slegs geïnokuleer is met die toetsorganismes het as kontroles gedien. Die groei van al die toetsorganismes is substansieël geïnhibeer (>-99.9%) in Kefir gedurende die 30 h inkubasieperiode. Substansiële afnames in logsiklusgetalle is waargeneem vir baie van die organismes. Dit het gepaard gegaan met 'n skerp afname in pH (6.57 - 4.06) en toename in titreerbare suurheid (0.20 - 0.72%) vir die Kefirmonsters gedurende die 30 h inkubasieperiode. lndien Kefir bemark word aan lae-inkomste stedelike Swart verbruikers sal dit moet kompeteer met Maas. Vergelykende sensoriese toetse is dus uitgevoer. Die verskille in die sensoriese eienskappe van Kefir, 'laboratorium' Maas (verteenwoordigend van tradisionele Maas) en kommersiële Maas (wat verdikker, kleur- en geurmiddels bevat) is bepaal deur 'n opgeleide paneel en geïdentifiseer as die" "gis-" en "koeismake" (p < 0.05), die "gasserigheid" (p < 0.01) asook die "suurheid", "romerigheid" en "gladheid" (p < 0.001) van die monsters. Die effek van verskillende inkubasietemperature (25°, 30° en 35°C) op die sensoriese eienskappe van Kefir is bestudeer om die effek van die groot temperatuurvariasies wat in laeinkomste behuising mag voorkom, te simuleer. Daar is bevind dat die "suurheid" en "romerigheid" van Kefir toeneem met verhoging in inkubasietemperatuur terwyl geen afsmake ontwikkel nie. Sensoriese voorkeurtoetse is deur verbruikerspanele van verskillende ouderdomme en bevolkingsgroepe uitgevoer om te bepaal of die spesifieke panele 'n beduidende voorkeur toon vir Kefir, laboratorium Maas of kommersiële Maas. Daar is bevind dat stedelike Swart jongmense kommersiële Maas beduidend (p < 0.001) bo Kefir verkies. Swart volwassenes met verwagte tradisionele smaakvoorkeure het egter Kefir en laboratorium Maas ewe veel verkies (p > 0.05). Hierdie segment van die Swart bevolking is dus die geskikte teikenmark vir die bekendstelling van Kefir. Voorkeur vir Kefir en laboratorium Maas is ook getoets deur 'n paneel (ouderdom 18 - 25 jaar) wat bestaan uit mense van verskillende bevolkingsgroepe. AI die groepe het Kefir en Maas ewe veel verkies (p > 0.05). Verskeie argumente ten gunste van die bemarking van Kefir aan lae-inkomste stedelike Swart gemeenskappe in Suid-Afrika is geïdentifiseer. Dit behels die volgende: die gerief van Kefirvervaardiging; die herbruikbaarheid van Kefirkorrels en gevolglike bekostigbaarheid; goeie verpakkings-, verspreidings- en opbergingsmoontlikhede; Kefir se aanvaarbaarheid vir laktose-intolerante individue; Kefir se hoë voedingswaarde; die inhiberende aktiwiteit wat Kefir teenoor potensiële bederf- en patogeniese organismes het en die gevolglike verhoging in veiligheid en rakleeftyd van melk; en Kefir se aanvaarbare verfrissende smaak.

Thesis (MSc Food Sc )--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The focus of this study was the development of food products produced from the neck flesh of Cape hake (Merluccius capensis) as a means of adding value to hake heads. The product prototypes that have been developed include curried fish chowder (packaged in stand-up pouches), fish spread (packaged in plastic casings) and Chakalaka hake (packaged in both cans and retortabie pouches). A formula for fish stock, which was used as a base ingredient in the three product prototypes, has also been standardised. Shelf life testing was regarded an essential part of the development processes for the refrigerated product prototypes i.e. the curried fish chowder and the fish spread. Shelf life determinations involved microbiological testing based on set microbiological standards as well as sensory monitoring and pH testing. Proximate chemical- and mineral analyses were performed on freeze-dried samples of the developed product prototypes. The efficiency of the antimicrobial peptides enterocin 1071 A and 1071 B, as biological preservatives, versus that of conventional artificial preservatives was evaluated in the fish spread prototype. Three batches of fish spread were prepared: one containing the enterocin crude extract; the second a combination of sodium benzoate and potassium sorbate, while the third batch containing no preservatives served as the control. Microbiological- and histamine tests coupled with organoleptic monitoring and pH testing were carried out over a 21-day period. It was concluded that although enterocins 1071A and 1071B had some preserving effect in the fish spread, the artificial preservative combination was the superior preserving agent. However, neither the biological preservatives nor the artificial preservative combination succeeded in providing a satisfactory shelf life. The preserving agents used in this study were however not necessarily included at optimum levels and higher levels could possibly lead to an improved shelf life. The influence of two processing temperatures [121°C (249.8°F) and 116°C (240.8°F)] and two food container types (retortable pouch and can) on the sensory quality characteristics of the Chakalaka hake-prototype was investigated. The results indicated that the shorter processing time obtained with a higher processing temperature resulted in a product of better sensory quality. The sensory quality characteristics of Chakalaka hake processed in cans at 121°C were closest to that considered desirable for the product. / AFRIKAANSE OPSOMMING: Die fokus van hierdie studie was die ontwikkeling van voedselprodukte geproduseer uit die nekvleis van stokvis (Merluccius capensis) met die doeI om waarde by stokviskoppe te voeg. Die volgende produk-prototipes is ontwikkel: 'n dik vissop met 'n kerriegeur (verpak in regopstaande sakkies), 'n vissmeer (verpak in plastiekomhulsels) en Chakalaka hake (verpak beide in blikkies en retortbestande sakkies). 'n Formule vir visaftreksel, wat as 'n basis-bestanddeel in die drie produk-prototipes gebruik is, is ook gestandaardiseer. Rakleeftydstudies het 'n belangrike deel van die ontwikkelingsprosesse van die verkoelde produk-prototipes, d.i. die dik vissop en die vissmeer, uitgemaak, Rakleeftydbepalings het mikrobiologiese toetsing, gebaseer op vasgestelde mikrobiologiese standaarde, sowel as die monitor van sensoriese eienskappe en pH metings behels. Proksimale chemiese- en mineraal analises is uitgevoer op gevriesdroogde monsters van die ontwikkelde produk-prototipes. Die effektiwiteit van die antimikrobiese peptiede enterosien 1071 A en 1071 B, as biologiese preserveermiddels, is ondersoek in vergelyking met dit van konvensionele kunsmatige preserveermiddels in die vissmeer-prototipe. Drie mengsels vissmeer is berei waarvan die eerste enterosien kru-ekstrak bevat het; die tweede 'n kombinasie van natrium bensoaat en kalium sorbaat, terwyl 'n derde mengsel geen preserveermiddels bevat het nie en gedien het as kontrole. Mikrobiologiese- en histamien toetse is gelyklopend met organoleptiese monitering en pH metings oor 'n tydperk van 21 dae op monsters van die drie vissmeermengsels uitgevoer. Die ondersoek het getoon dat enterosien 1071 A en 1071 B wel 'n mate van bederfwering in die vissmeer meegebring het, maar dat die kunsmatige preserveermiddelkombinasie 'n beter preserveringseffek gehad het in die produk. Nie die biologiese preserveermiddels óf die kunsmatige preserveermiddelkombinasie kon 'n bevredigende rakleeftyd teweegbring nie. Die preserveermiddels in hierdie studie is egter nie noodwendig in optimale hoeveelhede gebruik nie en hoër vlakke kan moontlik tot 'n verbeterde rakleeftyd lei. Die effek van twee prosesseringstemperature [121 °C (249.8°F) en 116°C (240.8°F)], sowel as twee verpakkingstipes (retortbestande sakkie en blik), op die sensoriese kwaliteitseienskappe van die 'Chakalaka hake' -prototipe is ondersoek. Die resultate het aangedui dat die korter prosesseringstyd verkry met 'n hoër prosesseringstemperatuur, gelei het tot 'n produk van beter sensoriese gehalte. Die sensoriese kwaliteitseienskappe van 'Chakalaka hake' geprosesseer in blikke by 121°C was die naaste aan dit wat beskou word as gewens vir die produk.

Thesis (MSc Food Sc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The start-up period of Upflow Anaerobic Sludge Bed (UASB) reactors can significantly be reduced by enhancing the time-consuming granulation process through the batch cultivation of anaerobic granular sludge and thus seeding the reactor with this cultivated granular sludge, instead of raw anaerobic sludge. The precise mechanism for granule formation is not well known, but it is believed that extracellular polymers (ECP) play a critical role in the granulation process. Information on the precise role of ECP is also limited and no universal standardised method for ECP extraction is used at present. Therefore, comparison of results from different researchers has to be made with great caution. The objectives of this study were to evaluate an ECP extraction methód so as to optimise the extraction time, and then to correlate ECP composition of UASB granules with granule metabolic activity. The impact of changes in the environmental conditions, such as sludge sources (Paarl and Kraaifontein-sludge), carbon growth substrates (yeast extract lactate, glucose medium and fruit cocktail effluent) and batch cultivation techniques (roller-table and shake-waterbath), on batch cultivation studies was also evaluated in terms of granule activity, ECP composition and granule formation. A physical extraction method was used to quantify the ECP content of UASB granules from six different sources. The optimal extraction time was taken as the time needed before cell lysis took place, and before intracellular material started contributing to the ECP content of the granules. It was concluded that the ECP composition was affected by the wastewater composition fed to the original UASB reactors, It was also found that the activity test results could be used to indirectly predict the activity of the different trophic groups present in the UASB granules. A correlation was found between the activity test results and the total ECP content, and this showed that the granules with the higher ECP yields exhibited greater biogas (SB) and methanogenic (SM) activities. However, based on the activity data and total ECP content, it appeared that a protein:carbohydrate ratio < 1 affected the activity of the granules, The sludge source used as inoculum for batch cultivation of anaerobic granular sludge had a significant effect on granule formation. The use of a pre- granulated raw anaerobic sludge, such as the Paarl-sludge, resulted in a greater increase in granule numbers at the end of the cultivation period. The acetic acid activity profiles showed that the acetoclastic methanogens that are involved in initiation of granulation by nucleus formation, were inactive or absent in the different batch systems, with the exception of the roller-table glucose cultivated Kraaifontein-sludge (RKG) batch system. The addition of glucose as carbon growth substrate for batch cultivation not only enhanced the activity of the acidogenic population, but also led to the establishment to a greater variety of granule trophic groups within all the glucose cultivated batch systems. The addition of fruit cocktail effluent as carbon substrate enhanced ECP production in the Paarl-sludge cultivated batch systems. However, the addition of carbon substrates showed no discernible trend on granule formation itself. The roller-table cultivation technique resulted in the higher increase in granule numbers, and it was speculated that the more vigorous shake-waterbath technique probably shortened the contact time between biomass and substrate. Large variations in the ECP composition of the different batch systems were found, and these were ascribed to the composition heterogeneity of different sludges. For future studies, it is advisable to characterise sludge, both chemically and microbiologically before using as inoculum. The selection of an appropriate sludge inoculum should then lead to optimisation of the granulation process. / AFRIKAANSE OPSOMMING: Die aanvangsperiode van "Upflow Anaerobic Sludge Bed" (UASB) bioreaktors kan noemenswaardig verminder word deur die tydsame granulasie proses te versnel deur die vooraf lot-kweking van anaërobe granulêre slyk waarmee 'n reaktor dus geïnokuleer kan word in plaas van rou anaërobe slyk. Die presiese meganisme van granulevorming is nog nie welbekend nie, maar daar word beweer dat ekstrasellulêre polimere (ECP) wel 'n kritiese rol speel in die granulasie proses. Inligting; oor die presiese rol van ECP is ook nog beperk, en tans word daar nog , geen universele standaard metode vir ECP-ekstraksie gebruik nie. Gevolglik moet resultate vanaf verskeie navorsers met groot omsigtigheid vergelyk word. Die doelwitte van hierdie studie was om 'n ECP ekstraksiemetode te evalueer deur die ekstraksietyd te optimiseer, en dan te korreleer met die ECP samestelling en metaboliese aktiwiteit van die UASB granules. Die inwerking van veranderinge in omgewingskondisies, soos slykbronne (Paarl- en Kraaifontein-slyk), koolstofbronne (gisekstrak-Iaktaat-, glukose-medium en vrugtekelkie-uitvloeisel) en lot-kwekingstegnieke (rol-tafel en skud-waterbad) op lot-kweking studies in terme van granule aktiwiteit, ECP-samestelling en granulevorming is ook ondersoek. 'n Fisiese ekstraksie metode is gebruik om die ECP-inhoud van UASB granules vanaf ses verskillende bronne te bepaal. Die optimale ekstraksietyd is geneem as die tyd benodig voordat sellise sal plaasvind en die intrasellulêre materiaal 'n bydrae sal lewer tot die ECP-inhoud van granules. Dit is afgelei dat die ECP-samestelling beïnvloed word deur die samestelling van die afvalwater wat vir die oorspronklike UASB bioreaktors gevoer is. Voorts is gevind dat die aktiwiteitstoets resultate indirek gebruik kan word vir die voorspelling van aktiwiteit van die verskillende trofiese groepe wat in die UASB granules teenwoordig is. 'n Korrelasie is gevind tussen die aktiwiteitstoets resultate en die totale ECP-inhoud wat aangedui het dat granules met hoër ECP opbrengste, beter biogas (SB) en metanogeniese (SM) aktiwiteit getoon het. Volgens die aktiwiteitsdata en totale ECP-inhoud het dit egter geblyk dat 'n proteïen:koolhidraat verhouding < 1 die aktiwiteit van granules beïnvloed het. Die slykbron wat as inokulum gebruik is vir lot-kweking van' anaërobiese granulêre slyk het 'n noemenswaardige invloed gehad op granulevorming. Die gebruik van 'n rou anaërobe slyk wat reeds 'n mate van granulasie getoon het, soos die Paarl-slyk, het 'n hoër toename in granule getalle aan die einde van die kwekingsperiode teweeg gebring. Die asynsuur aktiwiteitsprofiele het aangedui dat die asetoklastiese metanogene, wat hoofsaaklik betrokke is by inisiëring van granulasie deur kernvorming, onaktief of afwesig was in al die verskillende lotsisteme, met die uitsondering van die roltafel glukose-gekultiveerde Kraaifonteinslyk (RKG) lot-sisteem. Die toevoeging van glukose as koolstofbron vir lot-kweking het nie alleenlik die aktiwiteit van die asidogene populasie verhoog nie, maar het ook bygedra tot die vestiging van 'n groter verskeidenheid van granule trofiese groepe. Die toevoeging van vrugtekelkie-uitvloeisel as koolstofbron het die produksie van ECP verhoog in die Paarl-slyk gekweekte lot-sisteme. Die toevoeging van koolstofsubstrate het egter geen merkbare verandering getoon in granulasie opsigself nie. Die rol-tafel kwekingstegniek het 'n hoër toename in granule getalle tot gevolg gehad, en dit is gespekuleer dat die meer kragtige skud-waterbad tegniek waarskynlik die kontaktyd tussen die substraat en biomassa verkort het. Groot variasies is gevind in die ECP-samestelling van die verskillende lotsisteme, en dit is toegeskryf aan die heterogene samestelling van die verskillende slyke. Vir toekomstige navorsing is dit raadsaam om slyk voor gebruik as inokulum beide chemies en mikrobiologies te karakteriseer. Die keuse van 'n geskikte slyk-inokulum sal bydra tot die optimisering van die granulasie proses.

Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Over the last decade, studies on the quality of the water in many of South Africa.s rivers revealed an increase in pollution levels (DWAF, 1996; DWAF, 2000). In agricultural areas of the Western Cape many farmers draw water for irrigation from nearby rivers without knowing what the microbial pollution level is. In order to investigate the current quality of river water in some of the Western Cape.s major rivers and to explore the possibility of pathogen carryover from water onto produce, this research project was initiated. In an exploratory study over a five month period, the microbiological and water chemistry of three selected sites from the upper Berg and two from the Plankenbrug Rivers were assessed. Studied organisms included Salmonella, Staphylococcus, Listeria, endosporeformers, coliforms, Escherichia coli and intestinal Enterococci, while the chemical analysis consisted of pH, alkalinity, conductivity and chemical oxygen demand (COD). Faecal coliform counts ranging from 540 to 1 700 000 cfu.100ml-1 and 490 to 160 000 cfu.100ml-1 were found for the Berg and Plankenbrug Rivers, respectively. The water temperature ranged from 12º to 21ºC with COD values always below 100 mg.L-1. Potential human pathogens such as Salmonella, Staphylococcus, Listeria, endosporeformers, E. coli and intestinal Enterococci were frequently isolated from all five sites that were sampled. These results are of great concern to farmers, fresh produce retailers and consumers alike as the river water is regularly drawn for irrigation of produce that is later consumed raw or after a minimal processing step. From the exploratory study it was concluded that the water from all the sites were not suitable for use in irrigation practices as they regularly exceeded the guidelines for faecal coliforms and E.coli as set out by South African authorities. Irrigation with faecally polluted river water is one way that fruit and vegetables can become contaminated with foodborne pathogens. The risk of disease transmission from potential pathogens present in the irrigation water is influenced by the microbial load present and the numbers carried over to the produce. In this study the carry-over and survival of Escherichia coli on green beans, sugar-snap peas and cocktail tomatoes was assessed under controlled laboratory conditions. The produce was exposed to E.coli under different combinations of exposure times (5, 15 or 30 min), drying times (30 or 120 min) and different inoculum concentration ranges (107, 105, 104, 10³ and 10ª). In all cases a reduction of at least one log value in original inoculum number was found with the 10ª inoculums showing no survivors. Follow-up studies with an exposure time of 60 min and increased drying times of 6 or 12 h. Neither of these parameter changes affected the variation in numbers for the same inoculum or the E.coli survivors. Similar E.coli loads to those detected on the green beans were detected on the sugar-snap peas. The number of survivors on the cocktail tomatoes was much lower than found for the beans and peas. The number of survivors on the cocktail tomatoes was much lower than found for the beans and peas. This was attributed the 'smooth'surface of the tomato skin probably making attachment of the E.coli bacteria difficult. With the exception of the 10ª inoculum range, all E.coli survivors detected on the three types of produce studied exceeded the guideline numbers set for fresh produce. If similar survival patterns are to be found in the environment then results from this study should serve as a warning that the Plankenburg river water is unsafe for use in the irrigation of fresh produce. Some farmers are already treating river water with chlorine prior to irrigation to eliminate the chance of pathogen transfer onto produce. However, this is not a feasible solution for most farmers due to the high cost of implementing a system such as this. / AFRIKAANSE OPSOMMING: Oor die afgelope tien jaar het studies oor die gehalte van die water in baie van Suid-Afrika se riviere 'n toename in besoedelingsvlakke getoon. Baie boere in landbou gebiede van die Wes-Kaap wat watertrek vir besproeiing uit die nabygelee riviere is onbewus van die mikrobiese besoedelingsvlak van die rivier. Hierdie navorsingsprojek is geinisieer ten einde die huidige gehalte van die water in sommige van die Wes-Kaap se riviere te monitor, asook die moontlikheid van patogeen oordrag van die water na vars produkte te ondersoek. Met behulp van 'n verkennende studie oor . vyf maande tydperk, is die mikrobiologiese en water chemie kenmerke van drie geselekteerde moniteringspunte uit die boonste Bergrivier, en twee uit die Plankenburgrivier bemonster. Die bestudeerde organismes het ingesluit: Salmonella, Staphylococcus, Listeria, endosporeformers, fekale kolivorme, Escherichia coli en intestinale Enterococci. Die chemiese parameters het bestaan uit pH, alkaliniteit, geleiding, temperatuur en chemiese suurstof behoeftes (CSB). Fekale kolivorme tellings het gewissel van 540 - 1 700 000 cfu.100ml-1 en 490 tot 160 000 cfu.100ml-1 is gevind vir die Berg- en Plankenburgriviere, onderskeidelik. Die water temperatuur het gewissel van 12 º tot 21ºC met die CSB-waarde altyd onder 100 mg.L-1. Potensiele menslike patogene soos Salmonella, Staphylococcus, Listeria, endosporeformers, E. coli en intestinale Enterococci is dikwels geisoleer uit al vyf die moniteringspunte. Hierdie resultate is van groot belang vir boere, kleinhandelaars en varsprodukte verbruikers omdat die riviere se water gereeld onttrek word vir besproeiing van produkte wat later gebruik word in rou of in minimale geprosesseerde vorm. Vanuit die verkennende en uit die langer termyn studie (12 maande) is die gevolgtrekking gemaak dat die water vanuit die riviere nie geskik is vir gebruik in besproeiingspraktyke waar die riglyne vir fekale kolivorme en E. coli, soos uiteengesit deur die Suid-Afrikaanse owerhede, gereeld oorskry word nie. Besproeiing met fekale besoedelde rivierwater is een manier waarop groente en vrugte besmet kan word met voedsel patogene. Die risiko vir die oordrag van moontlike patogene teenwoordig in die besproeiingswater word beinvloed deur die mikrobiese lading teenwoordig en die getalle wat oorgedra word na die produkte. In hierdie studie is die oordrag en oorlewing van E. coli op groenboontjies, ertjies en tamaties onder beheerde laboratoriumtoestande beoordeel. Die produkte is blootgestel aan E. coli onder verskillende kombinasies van blootstellingstydperke (5, 15 of 30 min), drogingstye (30 of 120 min) en verskillende inokulum konsentrasies (107, 105, 104, 10³ en 10ª). In elke geval is . afname van ten minste een log waarde van die oorspronklike inokulum konsentrasie gevind. Die 10ª inokulum reeks het geen oorlewende selle getoon nie. Opvolg studies is gedoen met 'n blootstellingstyd van 60 min en verlengde drogingstye van 6 of 12 uur. Daar is gevind dat hierdie parameter veranderings die variasie in getalle vir dieselfde inokulum of die oorlewende E. coli nie beinvloed het nie. Soortgelyke E. coli ladings wat op die groenbone aangetref is, is ook op die ertjies aangetref. Die aantal oorlewendes op die tamaties was heelwat laer as die resultate vir die boontjies en ertjies. Dit word toegeskryf aan die "gladde" oppervlak van die tamatie-vel wat waarskynlik die aanhegting van die E. coli selle bemoeilik. Met die uitsondering van die 10ª inokulum reeks, het al die E. coli oorlewende selle gevind op die drie tipes produkte, die riglyn getalle oorskry wat vir vars produkte gestel is. As soortgelyke oorlewingspatrone gevind word in die omgewing, behoort die resultate van hierdie studie as waarskuwing te dien dat die water van die Plankenburgrivier ongeskik is vir die besproeiing van vars produkte. Sommige boere is reeds besig met chloor behandeling van die rivierwater voor besproeiing, om die kans van patogeenoordrag na die produkte uit te skakel. Dit is egter nie 'n haalbare oplossing vir die meeste boere nie as gevolg van die hoe kostes verbonde aan die implementering van' n stelsel soos hierdie.

Thesis (MSc Food Sc )--Stellenbosch University, 2003. / ENGLISH ABSTRACT: This study shows the potential of near infrared spectroscopy for both qualitative and quantitative analyses of wine and brandy in the distilling industry. Wines intended for further processing by the distillation industry have to meet certain specifications to ensure an efficient and cost-effective distilling process with a suitable product yield. Certain compounds have, therefore, been recognised as significant quality parameters and through their regulation, a product of consistent quality can be ensured. These quality parameters include alcohol, total acid, volatile acid, total sulphur dioxide, total phenolics, reducing sugars and acetaldehyde concentrations and pH. The effective control of all these compounds in the wines prior to distillation, is critical to maintain the feasibility and efficiency of the process. Fourier transform near infrared spectroscopy (FT-NIRS) can be used as a rapid and accurate analytical method for the determination of alcohol concentrations in distilling and brandy base wine. The choice of path length for the liquid sampling cell is an important consideration. In this study, alcohol with its strong absorption of OH bands in the near infrared region was not significantly affected, but difference in path length showed a significant influence on the prediction of the volatile acid concentration in distilling wine. Very strong correlations were found between the spectral data and the alcohol concentration data in distilling wine (r = 0.99, SEP = 0.18% v/v, RER =30) and brandy base wine (r = 0.92, SEP = 0.18% v/v, RER = 11.1). Good predictions were obtained for the volatile acid content of brandy base wine (r = 0.85, SEP = 0.04 g.L-1 ) but better accuracy could be obtained by incorporating a wider concentration range and more sensitive, although not the accepted reference methods, such as HPLC and GC, into the modelling. In contrast to the brandy base wine, the much cruder, turbid distilling wine (r = 0.67, SEP = 0.33 g.L-1 ) yielded poor calibration results for volatile acid. FT-NIRS can also be used as a rapid screening method to measure the total acid content, pH and total phenol levels in brandy base wine samples. Satisfactory predictions were obtained for the total acid content (r = 0.89, SECV = 0.38 g.L-1 ), pH (r = 0.84, SEP = 0.09) and total phenol levels (r = 0.71, SEP = 16.4 mq.L" GAE). The SEP of all the parameters compared well with the SEL and were within acceptable limits. The range of the concentration measurements were, however, very narrow and the accuracy of these models (measured as the ratio of the range to the standard error of prediction) were all below 10, indicating that modelling of these parameters in brandy base wine should be attempted with reference values covering a wider range. Poor correlations and predictions were obtained between the wine spectral data and the acetaldehyde (r = 0.39 , SECV =1.45 rnq.L"), residual sugar (r = 0.58, SECV =0.49 mq.L" ) and total sulphur dioxide (r = 0.35, SEP = 10.9 mq.L" ) concentration data. The unique character of potstill distillates, originating from the grape cultivar, type and age of the oak casks, lends itself to the development and blending of different brandies. The process of blending and correcting the brandy is necessary to obtain a product and brand of established and recognised character. The brandy is generally divided into different classes prior to blending based on the degree of "smoothness" or "hardness" of the matured distillate as determined by a sensorial panel. The ideal would, however, be to replace this subjective evaluation method with a more objective approach, such as an instrumental method like NIRS. Near infrared spectroscopy showed potential to successfully discriminate and classify brandy samples in terms of their sensorial classification status. The near infrared spectra of unblended three-year old brandies were measured and discriminant analysis performed using the subjective sensory classification data of the brandy. SIMCA (soft independent modelling of class analogy) models were developed by calculating separate peA (principal component analysis) models for each of the classes for which qualitative analysis were required. An assessment of class membership of an unknown sample was made on the basis of the distance to the cluster centroid. Two types of NIRS instruments, a Fourier transform near infrared system and a diode array spectrophotometer were employed to examine the discriminatory abilities of NIRS. Excellent predictions (90.9%-100%) were obtained for the "smoothest" and "hardest" classes within the 2000 and 2001 seasons with FT-NIRS. For the diode array spectra reasonable classification data were obtained for all the classes within the 2000 and 2001 seasons, as well as an excellent classification rate (100%) of the smoothest class in the 1999 season. Prediction results for class membership of the brandy samples from the three season's combined data did not deliver satisfactory discriminatory results. By applying NIRS and SIMCA, rapid and objective classification of brandy samples within seasonal context can be established to enhance the blending processes. Having accurate reference data in the calibration set is essential in near infrared spectroscopy (NIRS). The precision (usually decided by blind duplicate determination) of the reference data serves as the performance target for correlation-based near infrared analysis. The differences between reference values obtained from two independent laboratories and the Foss Winescan FT 120, which is also a predictive method, for the alcohol and volatile acid determinations in distilling wine and between two independent laboratories for the measurement of the total sulphur dioxide content, were investigated. ANOVA and post-hoc analysis (Bonferroni testing) revealed statistically significant differences (p<O.OS)between all three measurements for the volatile acid analysis. One laboratory differed significantly from the other two measurements in its measurement of the alcohol content in distilling wine. A paired t-test performed on the two laboratories' values obtained for total sulphur dioxide revealed statistically significant differences (p<O.OS) between the two sets of results. This study restated the importance of obtaining reliable reference data for calibration purposes to maintain the efficiency and accuracy and therefore the reputability of NIRS as an accurate and reliable analytical method. / AFRIKAANSE OPSOMMING: Hierdie studie dui op die potensiaal van naby infrarooi spektroskopie (NIRS) vir beide die kwalitatiewe en kwantitatiewe analise van wyn en brandewyn in die distillasie industrie. Sekere spesifikasies word gestel waaraan wyn met voldoen voor dit verdere prosessering tydens distillasie kan ondergaan. Die regulering van wynkwaliteit is noodsaaklik om die distilleringsproses ekonomies volhoubaar te maak. Sekere komponente in die wyn het 'n direkte invloed op die kwaliteit van die eindproduk en word beskou as betekenisvolle parameters wat beheer moet word om 'n produk van konstante hoë kwaliteit te lewer. Hierdie parameters sluit alkohol, titreerbare suur- en vlugtige suurinhoud, asook die pH, totale swaweidioksied, totale fenol vlakke, reduserende suikers en asetaldehied konsentrasies in. Die regulering van al hierdie komponente in die wyne is essensieel voor die aanvang van distillasie om die effektiwiteit en produktiwiteit van die proses te verseker. Fourier transformasie naby-infrarooi spektroskopie (FT-NIRS) kan benut word as 'n vinnige en akkurate analitiese metode om die alkohol konsentrasie in stook- en rabatwyn te bepaal. 'n Geskikte padlengte kuvet moet gekies word vir die ontleding van vloeistof monsters met NIRS. In hierdie studie is gevind dat die voorspelling van alkoholkonsentrasie in wyn, nie soseer beïnvloed is deur die keuse van padlengte nie. 'n Vlugtige komponent soos asynsuur, wat die maatstaf van die vlugtige suurinhoud van die wyn is, word egter regstreeks beïnvloed deur die keuse van padlengte. 'n Sterk korrelasie is gevind in die datastel vir die alkoholinhoud van die stookwyn (r = 0.99, SEP = 0.18% v/v, RER = 30) en rabatwyn (r = 0.92, SECV = 0.18% v/v, RER = 11.1). Baie goeie voorspellings is ook gevind vir die vlugtige suurinhoud van rabatwyn (r = 0.85, SEP = 0.04 g.L-1). Die akkuraatheid van die metode (uitgedruk as die RER waarde) het egter aangedui dat 'n wyer konsentrasie omvang en meer akkurate verwysingswaardes gebruik moet word om 'n geskikte model vir vlugtige suur kwantifikasie in rabatwyn te bewerkstellig. In teenstelling met die resultate verkry vir die rabatwyn, het die ruwer, turbiede stookwyn swak gekalibreer vir die vlugtige suurinhoud (r = 0.67, SEP = 0.33 g.L-1 ). FT-NIRS kan ook gebruik word as 'n vinnige seleksie metode om titreerbare suur vlakke, pH en totale fenolinhoud van rabatwyn monsters te bepaal. Sterk korrelasies is in die datastel gevind vir die titreerbare suurinhoud (r = 0.89, SECV = 0.38 g.L-1 ), pH (r = 0.84, SEP = 0.09) en totale fenol vlakke (r = 0.71, SEP = 16.4 rnq.L" GAE) van rabatwyn. Die SEP waardes verkry vanaf die NIRS bepalings het baie goed vergelyk met die standaard foute wat verkry is vir die chemiese bepalings. Die konsentrasie omvang van die verwysingswaardes was, egter, beperk en die akkuraatheid van die NIRS modelle (uitgedruk as die verhouding tussen die konsentrasie omvang en die standaard fout van voorspelling) was laer as 10. Dit het daarop gedui dat die NIRS kalibrasie van die parameters eerder uitgevoer moet word met monsters wat 'n wyer konsentrasie omvang dek en gemeet is met meer sensitiewe analitiese metodes soos HPLC en GC. Die kalibrasie en voorspelling van die asetaldehied inhoud (r = 0.39 , SECV =1.45 rnq.L"), reduserende suiker konsentrasie (r = 0.58, SECV =0.49 mq.L" ) en totale swaweldioksiedinhoud (r = 0.35, SEP = 10.9 rnq.L" ) het onaanvaarbare voorspellings gelewer. Die unieke karakter van potketel distillate wat bepaal word deur die druifkultivar, tipe en ouderdom van die eikehoutvate, bied die potensiaal vir die ontwikkeling en versnyding van verskillende style brandewyn. In 'n poging om 'n produk en handelsnaam van erkende en gevestigde karakter te verkry, moet die brandewyn eers versny word na veroudering. Die brandewyn word geklassifiseer in verskillende style op grond van sensoriese gehalte. NIRS is gebruik as 'n vinnige tegniek om te onderskei tussen verskillende style onversnyde drie jaar-oue brandewyn. SIMCA (soft independent modelling of class analogy) modelle is ontwerp deur aparte PCA (hoof komponent analise) modelle vir elke klas waarvoor kwalitatiewe analise vereis is, te ontwikkel. 'n Skating van klas lidmaatskap van 'n onbekende monster is gemaak deur die afstand van die monster na die groepsmiddelpunt te bereken. Twee soorte NIRS instrumente, 'n FT-NIR en 'n diode array spektrofotometer is gebruik tydens die studie om die diskrimineringsvermoë van elk te ondersoek. Uitstekende voorspellings (90.9%-100%) is gekry vir die "sagste" en "hardste" klasse binne die 2000 en 2001 seisoene met FTStellenbosch NIRS. Met die diode array spektra is redelike klassifikasie resultate verkry vir al die klasse binne die 2000 en 2001 seisoene, asook 'n uitstekende klassifikasie (100%) vir die sagste klas binne die 1999 seisoen. Voorspellings vir klas lidmaatskap van die brandewyn monsters vir die drie seisoene se gekombineerde data het egter onaanvaarbare diskriminasie resultate gelewer. NIRS en SIMCA sal 'n vinnige en objektiewe klassifikasie proses van onversnyde brandewyn monsters kan meebring wat tot voordeel van die versnydings- en produksieproses sal wees. Hierdie voorspellings sal egter binne seisoensverband moet geskied. Akkurate verwysingsdata in die kalibrasie datastel is 'n essensiële fasset van naby infrarooi spektroskopie. Die presisie (bepaal deur blinde duplikaat bepalngs) van die verwysingsdata dien as 'n prestasie teiken vir korrelasie-gebaseerde naby infrarooi voorspellings. Die verskille tussen die data verkry vir die alkohol- en vlugtige suurinhoud van stookwyn deur twee onafhanklike laboratoriums en 'n instrumentele metode (Foss Winescan FT 120) asook die verskille tussen die data verkry van twee laboratoriums vir die totale swaweidioksied metings, is ondersoek. ANOVA en post-hoc toetse het aangedui dat al die data verkry vir die vlugtige suur bepalings, statisties betekenisvol van mekaar verskil het (p<0.05). Vir die alkohol bepalings in stookwyn, het die data verkry van een laboratorium betekensvol verskil van die ander twee datastelle. Gepaarde t-toetse uitgevoer op die data verkry vir totale swaweldioksiedinhoud, het ook betekinisvolle verskille aangedui tussen die twee laboratoriums. Hierdie studie het die belangrikheid van betroubare verwysingsdata vir kalibrasie doeleindes beklemtoon, veral waar 'n tegniek soos NIRS se werksverrigting afhang van die akkuraatheid van dié waardes.

Thesis (MSc Food Sc )--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The effect of drying conditions on the retention of harpagoside, a glucoside iridoid found in the indigenous Southern African plant Harpagophytum procumbens (Devil's Claw), was investigated. Additionally, the feasibility of using near infrared spectroscopy (NIRS) as a rapid and nondestructive analytical tool for the prediction of the iridoids harpagoside (HS), 8-p-coumaroyl harpagide (8pCHG) and moisture contents, as well as the HS:8pCHG ratio in Devil's Claw was also studied. Due to the purported medicinal activity ofthe tuberous secondary roots, Devil's Claw is of commercial interest with a well established export market in Germany. The stability of HS during processing has, however, never been investigated and the current study evaluated the effect of three drying methods (sun, tunnel and freeze-drying), as well as three tunnel-drying temperatures (40°C, 50°C and 60°C, dry bulb temperature) on HS content. Methanolic extracts (70% methanol-water) were analysed by high-performance liquid chromatography (HPLC) and a multiple extraction test (n = 12) indicated a 91.70% recovery for HS. The comparative drying results showed significant (P < 0.05) differences between tunnel and freeze drying on the one hand and sun-drying on the other, with the latter being the most detrimental technique. In comparing tunnel-drying temperatures, at a constant relative humidity (RH) of30%, drying at 40°C showed the lowest retention ofHS, differing significantly (P < 0.05) from that at 50°C. Drying at 60°C did not differ significantly (P > 0.05) from either of the other two conditions, but also resulted in lower retentions ofHS content than drying at 50°C. Overall, freeze-drying showed excellent results for HS retention (1.565% ± 0.394%; mean ± standard deviation), but economic constraints limit the commercial application of this drying method. Although further study is required to optimise tunnel-drying conditions, this method indicated acceptable and practical results (1.526% ± 0.396%), especially with conditions set to 50°C and 30% RH (1.750% ± 0.438%). Future research should concentrate on elucidating the degradation mechanisms of HS during processing, transport and storage of dried Devil's Claw root. The analysis of dried, ground Devil's Claw root by NIRS was referenced to HPLC analyses of the same methanolic extracts used in the drying studies. The spectra were generated on two different NIRS instruments by measuring diffuse reflectance of the powder whilst calibrations were performed by partial least squares regression. Both independent data set validation and full cross-validation were used to evaluate the performance and predictive abilities of the various models. Excellent moisture content (MC) calibrations were developed with a standard error of prediction (SEP) ofO.24% (range: 2.44% to 10.43%) and correlation coefficient (r) of 0.99. For the given MC range, the model performed very well against the standard error of laboratory (SEL) ofO.14%. Considering the sensitivity of the HPLC reference method (SEL = 0.035%), the HS content calibration (range: 0.693% to 2.244%) performed admirably with an SEP ofO.134%. The available range was, however, relatively small and future NIRS studies should incorporate a larger range if possible. The 8pCHG model (range: 0.069% to 0.290%) performed similarly, with a standard error of cross-validation of 0.028% and SEL of 0.007%. By inclusion of a second species, H. zeyheri, both the 8pCHG content and especially HS:8pCHG ratio (range: 1.84 to 34.48) calibrations were evaluated as possible methods of distinguishing between species. With 8pCHG values of ca. 0.9%, good separation was achieved for the first model but, contrary to previous studies, the ratio was found to be less successful. Principle component analysis of the spectra, however, showed great potential as a qualitative tool for this purpose. It is believed that NIRS can become an invaluable tool for the division of Devil's Claw into export classes, depending on HS content. This content is, however, dependant on the drying conditions used and drying parameters should be optimised to ensure the best possible quality and retention ofHS. / AFRIKAANSE OPSOMMING: Die invloed van drogingskondisies op die behoud van harpagosied, 'n iridoïed glikosied wat in die inheemse Suider-Afrikaanse plant, Harpagophytum procumbens (Duiwelsklou) voorkom, is ondersoek. Die uitvoerbaarheid van naby infra-rooi spektroskopie (NIRS) as 'n vinnige en niedestruktiewe analitiese metode vir die voorspelling van die inhoud van iridoïede, harpagosied (HS), 8-p-kumaroïel-harpagied (8pCHG) en vog, sowel as die HS:8pCHG verhouding in Duiwelsklou is ook ondersoek. Die beweerde medisinale aktiwiteit van die knolagtige sekondêre wortels van Duiwelsklou het gelei tot 'n gevestigde uitvoermark in Duitsland, en is dus van kommersiële belang. Die stabiliteit van HS gedurende prosessering is nog nooit ondersoek nie. Die huidige studie het die invloed van drie drogingsmetodes (son-, tonnel- en vriesdroging) en drie tonneldrogingstemperature (40°C, 50°C en 60°C, droëbol temperatuur) op die HS inhoud evalueer. Metanolies ekstrakte (70% metanol-water) is met hoë-druk vloeistof chromatografie ("HPLC") geanaliseer en 'n veelvoudige ekstraksie toets (n =12) het 'n 91.70% herwinning van HS getoon. Betekenisvolle (P < 0.05) verskille is gevind tussen tonnel- en vriesdroging enersyds en sondroging andersyds, met laasgenoemde die nadeligste metode. Die vergelyking van tonneldrogingstemperature, by 'n konstante relatiewe humiditeit (RH) van 30%, het getoon dat droging by 40°C die minste HS behou het en betekenisvol (P < 0.05) verskil het van droging by 50°C. Alhoewel die droging by 60°C nie betekenisvol verskil het van die ander twee kondisies nie, het dit laer HS waardes as droging by 50°C getoon. Vriesdroging het uitstekende resultate ten opsigte van die behoud van HS gelewer (1.565% ± 0.394%; gemiddelde ± standaard afwyking), maar ekonomiese beperkings plaas noodgedwonge limiete op die toepaslikheid van hierdie drogingsmetode. Verdere studie om tonneldrogingskondisies te optimiseer word is nodig (1.526% ± 0.396%), maar veral droging by 50°C en 30% RH (1.750% ± 0.438%) het prakties aanvaarbare resultate gelewer. Toekomstige navorsing moet daarop gemik word om die spesifieke degradasie meganismes van HS gedurende die droging, vervoer en opberging van Duiwelsklouwortel te verklaar. Die NIRS ontleding van gedroogde, gemaalde Duiwelsklou wortel is vergelyk met HPLC analises van dieselfde metanolise ekstrakte wat tydens die drogingstudies gebruik is. Twee verskillende NIRS instrumente is gebruik om spektra deur diffuse weerkaatsing in die poeier te meet en kalibrasies is daaropvolgend met gedeeltelike minste vierkante ("PLS") regressie gedoen. Beide onafhanklike data stel validasie en volle kruisvalidasie is gebruik om die prestasie en voorspellingsvermoë van die onderskeie modelle te evalueer. Uitstekende voginhoud (VI) kalibrasies met 'n standaard voorspellings fout (SVF) van 0.24% (klasinterval: 2.44% tot 10.43%) en 'n korrelasie van 0.99 is gevind. Die model het goed vergelyk met die standaard laboratorium fout (SLF) van 0.14%, oor die gegewe klasinterval. Met inagneming van die sensitiwiteit van HDVC as verwysingsmetode (SLF = 0.035%), het die HS inhoud kalibrasie (klasinterval: 0.693% tot 2.244%) aanvaarbaar gepresteer met 'n SVF van 0.134%. Die beskikbare klasinterval was egter relatief klein en toekomstige NIRS studies moet gebruik maak van 'n wyer klasinterval indien moontlik. Die 8pCHG model (klasinterval: 0.069% tot 0.290%) het soortgelyk gepresteer, met 'n standaard kruisvalidasie fout van 0.028% en SLF van 0.007%. Met die insluiting van monsters van 'n tweede spesie, H. zeyheri, is beide die 8pCHG inhoud en HS:8pCHG verhouding (klasinterval: 1.84 tot 34.48) kalibrasies as moontlike metodes vir onderskeiding tussen die spesies geëvalueer. Met'n 8pCHG inhoud van ca. 0.9% het die eerste model 'n goeie skeidingsvermoë getoon. In teenstelling met vorige studies egter, het die verhoudingsmodel minder sukses getoon. Hoofkomponent analise ("PCA") van die spektra was egter baie belowend as 'n kwalitatiewe onderskeidingsmetode. Volgens hierdie studie kan NIRS 'n waardevolle tegniek wees vir die verdeling van Duiwelsklou in uitvoer klasse op grond van HS inhoud. Hierdie inhoud is egter grotendeels afhanklik van die drogingskondisies en drogingsparameters wat verder verfyn behoort te word om 'n produk van die hoogste kwaliteit met behoud van HS te verseker.