Thesis (PhD)--Stellenbosch University, 2005. / ENGLISH ABSTRACT: Please see fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2009. / An 84-day study was conducted to find a suitable diet and feeding level for the culture of South African abalone (Haliotis midae) in Namibia. Two experimental diets, namely, a seaweed diet (SWD) Laminaria pallida (macrophytic algae) and a formulated diet (FD) (macro-algae), for use in abalone (Haliotis midae) feed development, were evaluated. The animals used in this study were juveniles (24.33 ± 3.14 mm shell length; 2.72 ± 0.83 g live weight, mean ± SE) and sub-adults (58.07 ± 10.33 mm shell length and 41.96 ± 20.61 g live weight, mean ± SE). The nutrient profile of the SWD and FD displayed no differences in the protein and carbohydrate levels. Crude protein levels ranged from 4.91 to 17.68% (dry matter (DM) basis). The lipid levels in the FD (0.25%) were almost 0.56% lower than that in the SWD (0.76%). The feed conversion ratio (FCR) and protein efficiency ratio (PER) for the sub-adult abalone ranged from 2.80 to 10.90 and 0.10 to 0.40, respectively. The juvenile abalone fed on the FD yielded significantly lower (P < 0.05) FCRs (0.8) and higher PERs (1.20) than their counterparts fed on the SWD. A similar trend was observed for the sub-adult abalone although the differences were not significant (P > 0.05). The relative growth rate (RGR) of juvenile fed on the FD was 25% lower compared to those fed on the SWD, while that of the sub-adult abalone fed on the FD was 29% lower compared to the abalone fed on the SWD. From the daily growth rate (DGR) in terms of daily body weight (DGRBW) calculated after the 84-day period, repeated-measures ANOVA (RANOVA) indicated no interaction between time period and diet. Although slightly lower, the DGRBW for the juvenile abalone fed on the SWD diet (0.033 g/day) did not differ significantly from the DGRBW of abalone fed on the FD (0.079 g/day). In contrast, sub-adult abalone fed on the SWD exhibited significantly higher DGRBW compared to those fed on the FD. Although the abalone fed on the FD was slightly higher in nutritional content, there was no significantly difference (P > 0.05) in the nutritional profile of the abalone soft body tissue fed on either the SWD or FD. There was no significant (P > 0.05) difference in preference when comparing the aroma of the abalone meat samples fed on either the SWD or FD. However, there was a significant difference (P < 0.05) in the consumers’ preference in terms of flavour for the abalone sample fed on the FD. The trained taste panel results indicated that there was no difference in the aroma and flavour of the abalone fed on the different diets (P > 0.05). This study showed that cultured juvenile H. midae, readily accepted a FD, producing high consumption and survival rates. The FD still warrants further refinement and testing for it to become a more effective mariculture feed with commercial potential.

Thesis (Msc Food Sc (Food Science))--Stellenbosch University, 2008. / The physical and mental development of underprivileged children, living in developing countries, is detrimentally affected by the exposure to poverty, malnutrition and poor health. The aim of the present study was to determine the possible risk of nutritional deficiencies of children (aged 5 – 6 years) in a low socio-economic community in the Grabouw area of the Western Cape, South Africa. The nutritional status of the children was evaluated by using anthropometric measurements (weight and height). Furthermore, the dietary intake provided by the meals offered at the schools they attended (Agapé 1 and Agapé 2), was assessed using the school menus. The latter were analysed using the FoodFinder3® computer programme (Medical Research Council of SA, Tygerberg, South Africa). Three supplementary food products (biscuit, health bar and soy milk-based drink) were subsequently developed to address possible nutritional deficiencies. The microbial stability of the products was determined, after which sensory acceptability of all three products was determined using a consumer panel consisting of children (n = 51; M:F = 27:24; 5 – 6 years) from the mentioned schools within the low socio-economic community. Anthropometric results were in agreement with those found by the National Food Consumption Survey (NFCS) (1999) and the South African Vitamin A Consultative Group (SAVACG) (1995), with stunting found to be most prevalent (16%). Only 5% of the children were found to be underweight and none were found to be wasted. The developed biscuit and health bar was found to be microbiologically safe when stored for at least 30 d at 25° and 35°C respectively, and the soy milk-based drink for 7 d if stored at refrigeration temperatures (5°C). Concerning the sensory preference, no significant difference was found between the preference for any of the developed products by the males and the females. For the specific products the preference for the biscuit did not differ significantly from the health bar, nor did the health bar differ significantly from the soy milk-based drink, but the biscuit did differ significantly (p = 0.006) from the soy milk-based drink for preference. The biscuit was found to be the most preferred of the three products and the soy milk-based drink the least. The majority of the juvenile consumer panel (95%) found all three developed food products acceptable and could, therefore, be considered possible supplementary foods in a school nutrition programme. The aim of nutritional supplementation is to supplement the existing diet and in doing so ensuring a more ideal nutrient intake closer to what is recommended by the recommended dietary allowance (RDA). It is proposed that nutritional deficiencies should, however, not only be addressed by means of nutritional supplementation, but should also be assisted by the nutrition education of the parent/guardian so as help them to make informed nutritional choices and in doing so providing their children with the nutrients necessary for optimal mental and physical development.

Thesis (MSc Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The agricultural sector of South Africa is currently facing a serious water crisis. The decreased availability of water as a result of climate change and the constantly growing population has left many farmers increasingly dependant on surface water as primary source of irrigation. Urbanisation along with out-dated and insufficient wastewater treatment works have all contributed to polluting large volumes of these resources. Consequently, many farmers have been forced to use irrigation water, not only of poor quality, but often water which has been polluted with untreated sewage. As a result, this project aimed at investigating the link between the quality of irrigation water and the impact on the safety of fresh produce. A base-line of the microbial load at three sites along the Plankenburg and Eerste Rivers was established using standard microbial methods for the detection of indicator organisms such as total and faecal coliforms, Escherichia coli and Enterococci as well as potential pathogens that included Salmonella, Listeria, Staphylococcus, endosporeformers and aerobic colony counts. Chemical parameters such as pH, alkalinity, conductivity and chemical oxygen demand (COD) were also monitored, but were not correlated to microbial pollution levels in the rivers. High faecal coliform and E. coli concentrations, ranging from 310 to 7 x 106 cfu.100 mL-1 and 230 to 7 x 106 cfu.100 mL-1, respectively, were detected. The recommended irrigation water guidelines of ≤1 000 (WHO, 1989) and ≤4 000 cfu.100 mL-1 (DWAF, 2008) for faecal coliforms and E. coli were exceeded, indicating faecal pollution and thus a high health risk. This health risk was confirmed when potential pathogens such as Aerococcus viridans, Klebsiella, Listeria monocytogenes and Salmonella typhimurium were detected at all three sites. The carryover of organisms from rivers to produce (green beans and grapes) was investigated by comparing the microbial population of the Plankenburg and Eerste Rivers to the population recovered from irrigation water and the surface of fresh produce. Faecal coliforms, E. coli, Aerococcus viridans, Enterobacter aerogenes, Klebsiella, L. innocua, L. grayi, L. monocytogenes and Staphylococcus aureus were detected in all three sample types, indicating a similarity between the microbial populations found in the river, the irrigation water and produce. Thus, the transfer of potential pathogens from the rivers to produce is a strong possibility. The build-up of organisms on the surface of green beans as a result of multiple irrigations was also confirmed by an increase in faecal coliform concentrations from initial concentrations of none detected to 44 000 cfu.100 mL-1 over a 10 day irrigation period. Finally, microbial source-tracking techniques including multi-antibiotic resistance (MAR) profiling, and the API 20E classification system were used to determine genotypic and phenotypic characteristics of 92 faecal isolates (from irrigation water and produce) and 13 reference strains. Numerical classification systems was used to classify the 105 faecal isolates according to the degree of similarity between the genotypic and phenotypic characteristics of the 105 isolates. A high degree of similarity indicates a high probability that isolates originate from the same strain and therefore from the same source, thereby confirming the transfer of organisms Faecal isolates (93 and 98%, respectively) were found to be resistant to Vancomycin at both the 5 and 30 μg concentrations. The majority of isolates presented some resistance to Erythromycin (15 μg) and Ampicillin (25 μg), with 82% of isolates presenting an inhibition zone ≤4 mm. Isolates were sensitive towards Ciprofloxacin (1 and 5 μg), Ofloxacin (15 μg), Ceftriaxone (30 μg) and Cefotaxime (5 μg), which were able to inhibit the growth of 79.8, 93.3, 79.8, 88.5 and 71.2% of the isolates, respectively. The 13 medical reference strains all presented different genotypic and phenotypic characteristics and thereby indicated a high degree of variability between isolates from the same species. Finally, 35% of the isolates could be grouped together based on similar genotypic and phenotypic characteristics, therefore, more than a third of the faecal isolates obtained from the surface of the fresh produce was as a result of faecal contaminants in the irrigation water. It could therefore be concluded that a health risk is associated with the water from the Plankenburg and to a lesser extent, Eerste River when used as source of irrigation, thereby risking the transfer of potentially harmful organisms, present in the rivers as result of faecal pollution, to the surface of fresh produce. / AFRIKAANSE OPSOMMING: Suid-Afrika stuur tans af op 'n dreigende water krisis. Klimaatsverandering tesame met 'n spoedig groeiende bevolking het gelei tot 'n aansienlike vermindering in die land se varswaterbronne terwyl veranderende reënvalpatrone daartoe bygedra het dat talle boere al hoe meer afhanklik geword het van oppervlakvarswaterbronne as hul hoof-besproeïngsbron. Verstedeliking, armoede asook verouderde en onvoldoende infrastrukture het egter bygedra tot die besoedeling van baie van hierdie oppervlakvarswaterbronne. Gevolglik is meeste boere genoodsaak om klaar te kom met besproeïngswater van, nie net onaanvaarbare mikrobiese kwaliteit nie, maar dikwels water wat gekontamineer is met onbehandelde riool. Hierdie studie was gevolglik daarop gemik om die impak van die mikrobiologiese kwaliteit van besproeïngswater op die veiligheid van vars groente en vrugte te bepaal. Standaard mikrobiologiese metodes vir die bepaling van indikator organismes soos totale en fekale kolivorms, E. coli en enterococci asook potensiële patogene wat Salmonella, Listeria en Staphylococcus insluit, was gebruik om die mikrobiese lading by drie verskillende punte (P1, P2 en P3) in die Plankenburg en Eerste Rivier te bepaal. Chemiese parameters soos pH, alkaliniteit, konduktiwiteit en Chemiese Suurstof Behoefte was ook bepaal maar geen korrelasie kon tussen hierdie eienskappe en die mikrobiese besoedelingsvlakke getref word nie. Hoë konsentrasies fekale kolivorms en E. coli wat onderskeidelik vanaf 3.1 x 102 tot 7 x 106 kve.100 mL-1 en 2.3 x 102 tot 7 x 106 kve.100 mL-1 gestrek het en gereeld die voorgeskrewe riglyne van onderskeidelik ≤1 000 (WHO, 1989) en ≤4 000 kve.100 mL-1 (DWAF, 2008) oorskry het, was by al drie punte gevind. Hierdie resultate het gedui op fekale besoedeling wat gevolglik met 'n hoë gesondheidsrisiko geassosieer kon word. Hierdie risiko was bevestig deur die teenwoordigheid van talle potensiële patogene, soos Aerococcus viridans, Klebsiella, Listeria monocytogenes en Salmonella typhimurium, wat vanaf al drie punte geïsoleer was. Die oordrag van organismes vanaf die besoedelde riviere na vars vrugte en groente (groen bone en druiwe) was bepaal deur die mikrobiese lading in die Plankenburg en Eerste Rivier te vergelyk met dié verkry vanuit die besproeïngswater en vanaf groen bone wat besproei was met hierdie water. Fekale kolivorms, E. coli, Aerococcus viridans, Enterobacter aerogenes, Klebsiella, L. innocua, L. grayi, L. monocytogenes en Staphylococcus aureus was vanaf al drie die monster tipes geïsoleer. Hierdie resultate het gedui op eenderse mikrobiese populasies in al drie bronne en het daarom die moontlike oordrag van patogene bevestig. Die opbou van organismes as gevolg van veelvuldige besproeïngsessies aan die oppervlak van groen bone was bevestig deur die toename in fekale kolivorm konsentrasie vanaf 'n begin telling van nul tot 'n maksimum konsentrasie van 44 000 kve.100 mL-1. Laastens was mikrobiologiese bron naspeurbaarheidstegnieke soos multi-antibiotika weerstandbiedende profiele en die API 20E klassifikasie sisteem gebruik om individuele genotipe en fenotipe profiele van die 105 fekale isolate saam te stel. Numeriese klassifikasie sisteme was gebruik om die isolate op grond van ooreenkomste tussen hul individuele fenotipiese en genotipiese karaktereienskappe te groeppeer. 'n Hoë mate van ooreenkomstigheid sal dan daarop dui dat isolate van dieselfde besoedlingsbron afkomstig is en gevolglik die oordrag van organismes vanaf besproeïngswater na vrugte en groente bevestig. Onderskeidelik 93 en 98% van die fekale isolate het daarop gedui om weerstandbiedend te wees teen beide 5 en 30 μg Vancomycin. Die meerderheid isolate (82%) het ook 'n mate van weerstand teenoor Erythromycin (15 μg) en Ampicillin (25 μg) getoon met inhibisie sones ≤4 mm. Isolate was ook sensitief teenoor Ciprofloxacin (1 en 5 μg), Ofloxacin (15 μg), Ceftriaxone (30 μg) en Cefotaxime (5 μg). Hierdie antibiotikums was in staat om die groei van onderskeidelik 79.8, 93.3, 79.8, 88.5 en 71.2 % van die isolate te inhibeer. Alhoewel resultate 'n hoë mate van variasie tussen isolate van dieselfde spesie getoon het was dit nogtans moontlik om 35% van die isolate saam te groeppeer op grond van ooreenstemmende genotipe en fenotipe profiele. Meer as 'n derde van die fekale isolate wat vanaf die oppervlakte van die groente en vrugte geïsoleer was, was afkomstig vanaf fekale besmetting in die besproeïngswater. Die oordrag van potensieël patogene organismes vanaf besoedelde riviere na vars vrugte en groente tydens besproeïng was sodoende bevestig. 'n Hoë gesondheidsrisiko was gevolglik gekoppel aan die gebruik van water vanaf die Plankenburg Rivier, en in 'n minder mate die Eerste Rivier, as bron van besproeïngswater. / Water Research Commission / National Research Foundation

Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Agriculture in the Western Cape is not only one of the most important economic sectors but also provides many job opportunities. Over the last few years the sustainability of this successful industry has become threatened by the faecal pollution of rivers used to irrigate produce that will be consumed raw or after minimal processing. This situation not only poses an enormous risk to the health of the consumer but also to farmers who stand to lose their export licenses. The purpose of this study was to determine the microbial types and loads in river water, irrigation water and on irrigated produce. A baseline study was done on four sites in two Western Cape rivers. These sites were chosen to allow for the sampling of river water, irrigation water and irrigated produce so as to determine whether a link between the use of contaminated irrigation water and the microbial population found on irrigated produce exists. The physico-chemical analyses used in the study consisted of: pH, alkalinity, water temperature, conductivity and chemical oxygen demand. The microbial monitoring included the aerobic colony counts (ACC) and the enumeration of the total coliforms, faecal coliforms, staphylococci, enterococci, and aerobic and anaerobic sporeformers present in the water samples. The presence or absence of the potential pathogens like E. coli, Listeria and Salmonella, was also determined. During the baseline study faecal coliform counts as high as 160 000 organisms.100 mL-1 were noted in the Plankenburg River, while counts as high as 460 000 organisms.100 mL-1 were found in the Mosselbank River. Apart from this, high numbers of staphylococci and intestinal enterococci were often found, while E. coli, Listeria and Salmonella were present in samples from both of these rivers. Based on the results of the baseline study on the two rivers it was decided to do a more intensive study on the microbial load of the river and irrigation water as well as irrigated produce from the Mosselbank site. Lettuce and cabbages from a commercial farmer’s fields were chosen as the irrigated produce. During the warmer summer months, ACC counts in the river samples peaked at 12 8000 000 cfu.mL-1, while faecal coliform counts of 1 600 000 organisms.100 mL-1 were found. The three potential pathogens (E. coli, Listeria and Salmonella) were present in all the river samples taken during this period. While the counts of indicator bacteria in the irrigation water was often lower, faecal coliform counts as high as 1 600 000 organisms.100 mL-1 and several other potential pathogens were found on the irrigated lettuce and cabbage. This could indicate a possible “build-up” of contamination on the produce with the repeated application of the tainted irrigation water. According to guidelines published by DWAF in 2008, water to be used for irrigation should not contain more than 4 000 organisms.100 mL-1 faecal coliforms if it is used for the irrigation of crops that are to be consumed raw or after a minimal processing step, as this would increase the health risk to the consumer. Guidelines published by the South African Department of Health are even stricter and state that raw vegetables and fruit should not contain more than 200 coliform organisms per gram, while E. coli and L. monocytogenes should be absent in one gram, and Salmonella spp. in 25 grams of the produce, respectively. From the data obtained during this study it was evident that the two rivers monitored regularly contained faecal indicators at levels much higher than those proposed in national and international guidelines for safe irrigation, making them unfit for the irrigation of MPF’s. It could be concluded that the rivers investigated during this study contained high levels of faecal contamination. Since some of the pathogens isolated from the river and irrigation water and the irrigated produce, it suggests a carry-over of microbial contamination from the river water to the irrigated produce. This was, however, only done using the traditional international methods and the presence of specific pathogens should in future be confirmed by means of molecular techniques. / AFRIKAANSE OPSOMMING: Landbou is nie net die een van die belangrikste ekonomiese sektore in die Wes-Kaap nie, maar verskaf ook vele werksgeleenthede. Oor die afgelope paar jaar word die volhoubaarheid van hierdie suksesvolle industrie egter bedreig deur die fekale kontaminasie van riviere wat gebruik word vir die besproeiing van voedsel wat rou of na ‘n minimale prosesserings stap ingeneem word. Hierdie situasie hou nie net ‘n groot gevaar vir die gesondheid van verbruikers in nie, maar ook vir boere wat hul uitvoerlisensies hierdeur kan verloor. Die doel van hierdie studie was om die ladings en tipes mikrobes in rivier water, besproeiingswater en op besproeide produkte vas te stel. ‘n Basiese studie van vier liggings in twee Wes-Kaapse riviere is gedoen. Hierdie liggings is só gekies dat dit moontlik was om die rivier water, besproeiingswater en die besproeide produkte te monitor, en daar sodoende vasgestel kon word of daar ‘n verhouding is tussen die gebruik van gekontamineerde besproeiingswater en die mikrobe populasie wat op die besproeide produkte aanwesig was. Die fisiko-chemiese analises wat gedurende die studie gedoen is, het pH, alkaliniteit, water temperatuur, geleidingsvermoë en die chemiese suurstof vereiste (COD) ingesluit. Die mikrobiese analises het die aërobe kolonie tellings (ACC) en die enumerasie van die totale kolivorme, fekale kolivorme, staphylococci, enterococci en die aërobe en anaërobe spoorvormers ingesluit. Daar is ook vir die aanwesigheid van potensiële patogene soos E. coli, Listeria en Salmonella getoets. Gedurende die basiese studie is fekale kolovorme tellings van so hoog as 160 000 organismes.100mL-1 in die Plankenburg Rivier aangeteken, terwyl tellings van so hoog as 460 000 organismes.100mL-1 in die Mosselbank Rivier gevind is. Hoë tellings stafielokokki en intestinale enterokokki is gereeld genoteer, terwyl E.coli, Listeria en Salmonella uit die waters van beide hierdie riviere geïsoleer is. Gebaseer op hierdie resultate is daar besluit om ‘n meer intensiewe studie van die rivier, besproeiingswater en die besproeide produkte van die Mosselbank Rivier te doen. Blaarslaai en kool van ‘n kommersiële boer se lande is vir hierdie doel gekies. Gedurende die warmer somer maande het die aërobe kolonie tellings in die rivier ‘n piek van 12 800 000 kve.mL-1 bereik, terwyl fekale kolivorme tellings van 1 600 000 organismes.100mL-1 genoteer is. Die drie potensiële patogene (E. coli, Listeria en Salmonella) was aanwesig in al die monsters wat gedurende hierdie tydperk van die rivierwater geneem is. Alhoewel die tellings indikator bakterieë in die besproeiingswater meestal laag was, is tellings fekale kolivorme van so hoog as 1 600 000 kve.100mL-1 en verskeie ander potensiële patogene op die besproeide blaarslaai en kool gevind. Dit kan dui op ‘n moontlike opbou van kontaminasie op die produkte met die herhaalde besproeiing met gekontamineerde besproeiingswater. Volgens die riglyne wat in 2008 deur DWAF gepubliseer is, mag water wat vir die besproeiing van minimaal geprosesseerdevoedsels gebruik word nie meer as 4 000 organismes.100mL-1 bevat nie, aangesien dit die gesondheid van die gebruiker in gevaar mag stel. Die riglyne van die Suid-Afrikaanse Departement van Gesondheid is selfs strenger en beveel aan dat rou vrugte en groente nie meer as 200 kolivorme en geen L. monocytogenes per gram, en geen Salmonella spp. in 25 g van die produk mag bevat nie. Vanuit die data wat tydens hierdie studie ingesamel is, is dit duidelik dat die twee riviere gereeld fekale indikators bevat het teen vlakke baie hoër as wat in die nasionale en internasionale riglyne aanbeveel word. Hierdie water is dus nie geskik vir die besproeiing van minimaal geprosesseerde produkte nie. Die afleiding kan gemaak word dat die riviere wat tydens hierdie studie gemonitor is, hoë vlakke van fekale kontaminasie bevat het. Aangesien sommige van die patogene vanuit beide die rivier- en besproeiingswater, en vanaf die besproeide produkte geïsoleer is, kan dit dui op ‘n moontlike oordrag van mikrobiese kontaminasie vanuit die rivierwater na die besproeide produkte. Tydens hierdie studie is daar egter net van die tradisionele internasionale metodes gebruik gemaak. Vir toekomstige navorsing word dit aanbeveel dat die aanwesigheid van die spesifieke patogene deur die gebruik van molekulêre metodes bevestig word.

Thesis (MScFoodSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The regular consumption of probiotics is becoming a recognized trend in the food industry due to several reported health benefits. A probiotic is defined as a live microbial feed supplement that beneficially affects the host animal by improving its intestinal microbial balance. A wide variety of probiotic food products are available on the South African market and comprise an assortment of fermented milks, as well as lyophilized preparations in tablet or capsule form. Strains of Lactobacillus acidophilus and Bifidobacterium species are mostly used as probiotic microbes in the industry due to their health enhancing effect. The survival of sensitive probiotic microbial species in food matrices are influenced by various factors such as oxygen concentration, pH levels and manufacturing and storage conditions. These should be considered and monitored as the South African food and health regulations stipulate that probiotic microbes should be present at a concentration of 10⁶ cfu.ml ̄ ¹' in order to exert a beneficial effect. Some health benefits are also correlated to specific microbial species and strains and these factors have resulted in the need for the rapid and accurate identification of probiotic microbes present in food products. The probiotic microbes present in probiotic yoghurts and supplements have in the past been identified using traditional methods such as growth on selective media, morphological, physiological and biochemical characteristics. However, even some of the most sophisticated cultural-dependant techniques are not always sufficient for the identification and classification of especially Bifidobacterium, as well as closely related Lactobacillus species. Molecular techniques are more often employed for the rapid and accurate detection, identification and characterization of microbial species present in food products. The aim of this study was to detect and identify the probiotic species present in various commercial South African yoghurts and lyophilized preparations using peR-based DGGE analysis. A 200 bp fragment of the V2-V3 region of the 16S rRNA gene was amplified and the peR fragments were resolved by DGGE. The unique fingerprints obtained for each product were compared to two reference markers A and B in order to identify the bands present. The results obtained were verified by species-specific peR, as well as sequence analyses of bands that could not be identified when compared to the reference markers. Only 54.5% of the South African probiotic yoghurts that were tested did contain all the microbial species as were mentioned on the labels of these products, compared to merely one third (33.3%) of the lyophilized probiotic food supplements. Some Bifidobacterium species were incorrectly identified according to some product labels, while other products contained various microbes that were not mentioned on the label. Sequence analysis confirmed the presence of a potential pathogenic Streptococcus species in one of the yoghurt products and in some instances the probiotic species claimed on the labels were non-scientific and misleading. The data obtained in this study showed that the various South African probiotic products tested were of poor quality and did not conform to the South African regulations. peR-based DGGE analysis proofed to be a valuable approach for the rapid and accurate detection and identification of the microbial species present in South African probiotic products. This could help with future implementation of quality control procedures in order to ensure a reliable and safe probiotic product to the consumer. / AFRIKAANSE OPSOMMING: Die gereelde inname van probiotiese produkte is besig om In erkende tendens in die voedselindustrie te word, as gevolg van verskeie gesondheidsvoordele wat daaraan gekoppel word. In Probiotika word gedefinieer as In voedingsaanvulling wat uit lewendige mikrobes bestaan en wat In voordelige effek op mens of dier het deur In optimale mikrobiese balans in die ingewande te handhaaf. In Wye verskeidenheid probiotiese voedselprodukte is tans beskikbaar op die Suid- Afrikaanse mark. Hierdie bestaan hoofsaaklik uit verskeie gefermenteerde melkprodukte asook 'n reeks tablette en kapsules wat probiotiese mikrobes in gevriesdroogde vorm bevat. Lactobacillus acidophilus tipes en Bifidobacterium spesies word die algemeenste in die voedselindustrie gebruik aangesien hierdie spesifieke mikrobes bekend is om goeie gesondheid te bevorder. Die oorlewing van sensitiewe probiotiese mikrobiese spesies in voedsel matrikse word beïnvloed deur faktore soos suurstof konsentrasie, pH-vlakke en vervaardigings- en opbergings kondisies. Hierdie faktore moet in aanmerking geneem word en verkieslik gemonitor word aangesien die Suid-Afrikaanse voedsel en gesondheids regulasies stipuleer dat probiotiese mikrobes teen In konsentrasie van 10⁶ kolonie vormende eenhede per ml teenwoordig moet wees om In voordelige effek te toon. Sommige gesondheidsvoordele word direk gekoppel aan spesifieke mikrobiese spesies en spesie-tipes. Hierdie faktore het gelei tot In groot aanvraag na vinnige en akkurate metodes vir die identifikasie van probioties mikrobes in voedselprodukte. Die probiotiese mikrobes teenwoordig in probiotiese joghurts en ook die gevriesdroogde vorms in tablette en kapsules, was al geïdentifiseer deur gebruik te maak van tradisionele metodes soos groei op selektiewe media, morfologiese, fisiologiese en biochemiese eienskappe. Selfs van die mees gesofistikeerde kultuur-afhanklike tegnieke is egter nie altyd voldoende vir die identifikasie en klassifikasie van veral Bifidobacterium en na-verwante Lactobacillus spesies nie. Molekulêre metodes word dikwels aangewend vir die vinnige en akkurate deteksie, identifikasie en karakterisering van mikrobes teenwoordig in voedselprodukte. Die doel van hierdie studie was om die probiotiese mikrobes teenwoordig in verskeie Suid-Afrikaanse joghurts en gevriesdroogde aanvullings, te identifiseer deur gebruik te maak van polimerase kettingreaksie (PKR)-gebaseerde denaturerende gradiënt jelelektroforese (DGGE) analise. 'n PKR fragment van 200 bp van die V2-V3 gedeelte van die 16S ribosomale RNS (rRNS) geen is geamplifiseer, en die PKR fragmente is geskei met behulp van DGGE. Die unieke vingerafdrukke wat verkry is vir elke produk is teen twee verwysings merkers A en B vegelyk om die bande teenwoordig in die profiele te identifiseer. Die resultate is bevestig deur spesies-spesifieke PKR en ook deur die ketting volgordes van die DNS fragmente te bepaal wat nie geïdentifiseer kon word deur vergelyking met die verwysings merkers nie. Slegs 54.5% van die Suid-Afrikaanse probiotiese joghurts wat getoets is het al die mikrobiese spesies bevat soos aangedui was op die etikette van hierdie produkte, teenoor slegs 'n derde (33.3%) van die gevriesdroogde voedingsaanvullings. Sekere Bifidobacterium spesies is verkeerd geïdentifiseer op sommige van die produk etikette, terwyl ander produkte verskeie mikrobes bevat het wat nie op die etiket aangedui was nie. 'n Potensiële patogeniese Streptococcus spesie is in een van die joghurt produkte gevind soos bevestig deur DNS kettingvolgorde bepalings. In sommige gevalle was die probiotiese spesienaam wat aangedui is op die etiket onwetenskaplik en misleidend. Die resultate wat uit hierdie studie verkry is dui aan dat die Suid-Afrikaanse probiotiese produkte wat getoets is van 'n swak gehalte is en nie aan die Suid- Afrikaanse regulasies voldoen nie. Daar is getoon dat PKR-gebaseerde DGGE analise 'n waardevolle tegniek kan wees vir die akkurate deteksie en identifisering van die mikrobiese spesies teenwoordig in probiotiese produkte. Dit kan help met die toekomstige implementering van kwaliteitskontrolerings prosedures om 'n mikrobiologiese betroubare en veilige produk aan die verbruiker te verseker.

Thesis (MSc Food Sc )--Stellenbosch University, 2000. / ENGLISH ABSTRACT: This study shows Fourier transform near infrared (FT-NIR) spectroscopy's application on wine, fruit and dried fruit for quantitative determinations or as a discriminative method for classification purposes. During wine production optimum yeast growth, resulting in healthy alcohol fermentation rates, is monitored by the amount of free amino nitrogen (FAN) present in the must. The status of malolactic fermentation (MLF) in Chardonnay wines is monitored by determining the degree of conversion of malic to lactic acid. Ethyl carbamate (EC), a suspected carcinogen, is mainly formed during ageing of wine and is restricted by legislation in some countries. It is therefore necessary to determine the EC content in wine. Fourier transform near infrared spectroscopy can be used on wine as a rapid method to measure the °Brix (residual sugars) content of must and to discriminate between different must samples in terms of their FAN values. It can also be used as a rapid method to discriminate between Chardonnay wine samples in terms of the MLF status and between table wine samples in terms of the EC content. Calibrations were derived and it was found that a very strong correlation existed in the sample set for the FT-NIR spectroscopic predictions for °Brix (r = 0.99, SEP = 0.31%), but poorer correlations for the FAN (r = 0.405, SEP = 275%), malic acid (r = 0.64, SEP = 1.02%), lactic acid (r = 0.61, SEP = 1.35%) and EC predictions (r = 0.47, SEP = 3.6%). When soft independent modelling by class analogy (SIMCA) was applied as a discriminative method, the must and wine samples were classified in terms of their FAN and EC values and MLF status, respectively, obtaining results with recognition rates exceeding 80%. The canning of peaches has become a significant industry in South Africa, producing approximately 4.1 million cartons per year. Fourier transform near infrared spectroscopy was applied as an alternative non-destructive method for the quantitative determination of the total soluble solid (TSS) content of whole fresh peaches. The TSS content of fresh clingstone peaches is an indication of the internal quality, maturity and perceived sweetness of the fruit for the peach canning industry. By determining the TSS, fresh peaches can be graded and the farmers compensated accordingly. Results obtained by building QUANT+™calibrations for the TSS content (r = 0.96, SEP = 0.55%) showed acceptable accuracy and can replace the present destructive methods. Peak periods during the harvesting season necessitate storage of peaches for up to three weeks before canning. Approximately 5 - 10% of the peaches stored, disintegrate during canning due to loose skin, large stone cavities, soft flesh and rot. The storage potential of fresh clingstone peaches can be successfully predicted with FT-NIR and SIMCA models, using subjective internal quality evaluations. Results with recognition rates exceeding 80% were obtained in most cases and this method proved useful as a non-destructive method of quality assessment. By applying this method, losses caused when storing peaches with poor storage quality will be reduced. The golden sultana industry plays an important role in the dried fruit exporting market of South Africa. Due to the large numbers of consignments that must be checked upon arrival, and the need for rapid decision making during processing, it is essential to replace the present time-consuming analytical methods. Fourier transform near infrared spectroscopy was used as a rapid, analytical technique to determine whether the S0₂ and moisture contents of sultanas are within specifications upon arrival at the factory and during processing. High positive correlation was found between the measured values and those predicted by FT-NIR spectroscopy for S0₂ (r = 0.99, SEP = 24.09%) and moisture (r = 0.99, SEP = 0.051 %) contents. / AFRIKAANSE OPSOMMING: Hierdie studie dui op Fourier transformasie naby-infrarooi (FT-NIR) spektroskopie se toepassing op wyn, vrugte en droëvrugte vir die uitvoer van kwantitatiewe bepalings of vir klassifikasie doeleindes om as 'n diskriminasie metode te dien. Gedurende wynproduksie word die optimum groei van giste wat lei tot 'n gesonde alkohol fermentasie gemonitor deur die hoeveelheid vry-aminostikstof (VAS) wat in die mos teenwoordig is te bepaal. Die status van appelmelksuurgisting (AMG) in Chardonnay wyne word gemonitor deur die mate van omskakeling van appelsuur na melksuur te bepaal. Etielkarbamaat (EK), 'n vermoede karsinogeen wat hoofsaaklik in verouderde wyne voorkom, word in sekere lande deur wetgewing beperk en dus die bepaling van die EK inhoud van wyne noodsaak. Fourier transformasie naby-infrarooi spektroskopie kan op mos toegepas word as 'n vinnige metode vir die bepaling van °Brix (residuele suiker) en om tussen die monsters te onderskei in terme van hulle VAS inhoud. FT-NIR kan ook gebuik word as 'n vinnige metode om tussen Chardonnay monsters te onderskei op grond van die status van AMG en tussen tafelwyn monsters op grond van die EK inhoud. Kalibrasies is ontwikkel en daar is gevind dat baie sterk korrelasies bestaan in die monsterstel vir die FT-NIR spektroskopiese voorspelling van °Brix (r = 0.99, SEP = 0.31%), maar swakker korrelasies vir die VAS (r = 0.405, SEP = 275%), appelsuur (r = 0.64, SEP = 1.02%), melksuur (r = 0.61, SEP = 1.35%) en EK voorspellings (r = 0.47, SEP = 3.6%). Met die toepassing van soft independent modelling by class analogy (SIMCA) as diskriminasie metode, is die mos- en wynmonsters geklassifiseer op grond van hul VAS en EK waardes en die status van AMG, en herkenningswaardes van bo 80% is onderskeidelik behaal. Die inmaak van perskes het 'n beduidende industrie in Suid-Afrika geword en produseer jaarliks ongeveer 4.1 miljoen kartonne. Fourier transformasie nabyinfrarooi spektroskopie is toegepas as alternatiewe, nie-beskadigende metode om kwantitatiewe bepalings van die totale oplosbare vastestowwe (TOV) inhoud van heel vars perskes, te doen. Vir die perske inmaak-industrie is die TOV inhoud van vars taaipitperskes 'n aanduiding van interne kwaliteit, rypheid en die soetheid van die vrugte. Vars perskes kan gradeer word deur die TOS te bepaal en sodoende kan boere oreenkomstige vergoeding ontvang. Resultate' wat verkry is deur QUANT+™ kalibrasies vir TOS inhoud te ontwikkel (r = 0.96, SEP = 0.55%), dui op aanvaarbare akkuraatheid en kan die huidige metodes vervang. Tydens oestyd kom piektye voor wanneer dit soms nodig is om perskes vir tot drie weke op te berg voordat dit ingemaak kan word. Ongeveer 5 tot 15% van hierdie opgebergte perskes disintegreer tydens inmaak omdat opberging lei tot defekte in die perskes soos skille wat loskom, groot pitholtes, sagte vleis en vrot. Die opbergingspotentiaal van vars taaipitperskes kan suksesvol voorspel word deur FTNIR en SIMCA modelle te bou en subjektiewe interne kwaliteitsevaluerings daarop toe te pas. Herkenningsresultate wat 80% in die meeste gevalle oorskry, is behaal wat hierdie metode as 'n suksesvolle nie-beskadigende kwaliteitbepalingsmetode bewys. Hierdie metode sal verliese kan beperk wat voorkom as gevolg van opberging van perskes met swak opbergingskwaliteit. Die goue sultana industrie speel 'n belangrike rol in die droë vrugte uitvoermark van Suid-Afrika. As gevolg van die hoeveelheid monsters wat gelyktydig getoets moet word en besluite wat vinnig geneem moet word tydens prosessering, is dit belangrik om die huidige tydrowende analitiese metodes te vervang. Fourier transformasie naby-infrarooi spektroskopie is gebruik as 'n vinnige, analitiese tegniek om tydens ontvangs by die fabriek en gedurende prosessering te bepaal of die S0₂- en voginhoud van goue sultanas binne die spesifikasies val. Goeie positiewe korrelasie is gevind tussen die bepaalde en voorspelde FT-NIR spektroskopiese waardes vir SO₂- (r = 0.99, SEP = 24.09%) en voginhoud (r = 0.99, SEP = 0.051 %).