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OBJECTIVES: Qualitative studies nested within clinical trials can provide insight into the treatment experience, how this evolves over time and where improved supportive care is required. The purpose of this qualitative study is to describe the lived experiences of men with advanced prostate cancer participating in the TheraP trial; a randomised trial of 177Lu-PSMA-617 compared with cabazitaxel chemotherapy. METHODS: Fifteen men with advanced prostate cancer were recruited from the TheraP clinical trial with interviews conducted at three timepoints during the trial. An interpretative phenomenological approach was used, and interviews analysed using thematic analysis. This research paper reports the results from the mid-point, conclusion and follow up interviews, focusing specifically on participants' experiences of trial participation. RESULTS: Three themes were identified representing the lived experiences of men with advanced prostate cancer participating in the TheraP trial: (1) facing limited options; (2) anticipating outcomes and (3) coping with health changes. CONCLUSIONS: Men who enrol in clinical trial of anti-neoplastic treatments for prostate cancer need targeted psychological and supportive care that includes attention to unique aspects of the experience of having prostate cancer and being in a clinical trial. As part of their trial experience, men with advanced prostate cancer need to be regularly assessed for survivorship needs, fully informed, supported and referred to services for regular care and support across the trajectory of their disease. TRIAL REGISTRATION: NCT03392428. Registered on 8 January 2018 (ANZUP1603).

OBJECTIVES: Qualitative studies nested within clinical trials can provide insight into the treatment experience, how this evolves over time and where improved supportive care is required. The purpose of this qualitative study is to describe the lived experiences of men with advanced prostate cancer participating in the TheraP trial; a randomised trial of 177Lu-PSMA-617 compared with cabazitaxel chemotherapy. METHODS: Fifteen men with advanced prostate cancer were recruited from the TheraP clinical trial with interviews conducted at three timepoints during the trial. An interpretative phenomenological approach was used, and interviews analysed using thematic analysis. This research paper reports the results from the mid-point, conclusion and follow up interviews, focusing specifically on participants' experiences of trial participation. RESULTS: Three themes were identified representing the lived experiences of men with advanced prostate cancer participating in the TheraP trial: (1) facing limited options; (2) anticipating outcomes and (3) coping with health changes. CONCLUSIONS: Men who enrol in clinical trial of anti-neoplastic treatments for prostate cancer need targeted psychological and supportive care that includes attention to unique aspects of the experience of having prostate cancer and being in a clinical trial. As part of their trial experience, men with advanced prostate cancer need to be regularly assessed for survivorship needs, fully informed, supported and referred to services for regular care and support across the trajectory of their disease. TRIAL REGISTRATION: NCT03392428. Registered on 8 January 2018 (ANZUP1603).

Medicinal mushrooms have had applications for centuries as an alternative treatment of various ailments. Their nutritional value adds to their popularity and has been extensively studied as a healthy source of food which are rich in protein. Two medicinal mushrooms, Ganoderma lucidum and Hericium erinaceus have been scrutinized in recent years due to the presence of bioactive compounds. Although a non-edible mushroom, G. lucidum is considered to possess the most medicinal properties and cultivation may have the potential of providing animal feed. The edible H. erinaceus is currently scrutinized as it may have application as a natural alternative to treat the symptoms associated with Alzheimer’s and cognitive decline. This study focused primarily on highlighting the advantages both mushrooms hold for humankind and pave the way for alternative medicinal applications. In chapter 2, the optimum growth conditions for the cultivation of G. lucidum and H. erinaceus have been investigated in order to allow exploitation of their medicinal and economic benefits. In this chapter, pure cultures of G. lucidum and H. erinaceus were required with the need for a single medium allowing cultivation of both species being imperative. Sorghum agar was developed and found to be a superior growth medium compared to MEA or YMA. For cultivation of G. lucidum, the encroaching tree species, Acacia mellifera, were used as substrate for cultivation in order to provide animal feed. Various factors, such as improved lighting and different lighting cycles, humidity control and CO2 regulation were taken in consideration and modified to improve yields. Cultivation of H. erinaceus was conducted on both A. mellifera wood and pecan nut shells, which proved to be a sustainable method for removal of these waste products. Factors such as humidity control resulted in high yields of H. erinaceus fruiting bodies. As running costs were reduced, both G. lucidum and H. erinaceus were used for the development of

Biogas production follows the normal anaerobic digestion process, this process can be divided into four major steps: hydrolysis, acidogenesis, acetogenesis and methanogenesis. The components of biogas are primarily methane and carbon dioxide, but it may contain small amounts of hydrogen, nitrogen, hydrogen sulphide and moisture; the composition of biogas also depends upon feed material. Biogas is a low-cost energy source derived from renewable resources; this is because it can be produced from any organic waste, including household food waste, animal waste and agricultural residue. These are wastes that will continue to be produced as long as humans live on earth and keep livestock. Cow dung, for example, is known to contain the necessary microorganisms, such as acid and methane formers, for biogas production. The biogas can be harnessed (and made environmentally friendly) by converting it to a fuel. Biogas digester systems provide a residue organic waste, after the anaerobic digestion (AD), this effluent is called digestate and has superior nutrient qualities over normal organic fertilizer. Biogas digesters also function as waste disposal systems, and can therefore prevent potential sources of environmental pollution and the spread of pathogens and disease-causing bacteria. The first step of AD is hydrolysis, during which the complex organic matter (polymers) are degraded into smaller units (mono and oligomers). During hydrolysis, polymers like carbohydrates, fats and proteins are converted into glucose, lipids and amino acids. Hydrolytic microorganisms release hydrolytic enzymes, converting biopolymers into simpler and soluble compounds. A variety of microorganisms are involved in hydrolysis, these bacteria are mostly strict or facultative anaerobes such as Bacteriocides, Clostridia and Streptococci. The products produced from hydrolysis are further metabolized by the microorganisms involved in the subsequent step. During acidogenesis, the products of hydrolysis a, Technology Innovation Agency

English: Available literature emphasises the importance of food safety in obtaining coordinated and conceptually informed results of food security, with the view to improve intervention programmes to achieve progress in obtaining food security in households. The study was undertaken intending to investigate possible food safety indicators that might possibly contribute towards improved assessment of household food security (HFS) in the rural Vhembe District, Limpopo Province, South Africa. The objectives were to determine HFS and household food safety, as well as the relationship between HFS and food safety, and to develop food safety indicators of HFS. A cross-sectional study was undertaken. Twenty nine villages were randomly selected from the total number of 299 villages in Thulamela local municipality in the Vhembe District. For proportional sampling of households from the selected villages 4 village clusters were created according to their population sizes. Households were randomly selected from villages. The final randomly selected sample consisted of 335 households with at least 1 child (3-5 years of age) and a caregiver. The caregiver could be the mother of the child or any caregiver over the age of 18 years of age who was mostly responsible for food preparation in the household. A structured interview schedule was used, consisting of questionnaires and data/record sheets that were completed during an interview with the respondent of each household. A sociodemographic questionnaire; food availability and access questionnaire; a food inventory; an 8-item hunger scale; a food frequency questionnaire; a food handling practices questionnaire; and a food handling knowledge test; a 24 hour recall and child health status questionnaire; as well as record sheets were included. Five repeatedly trained (for consistency) field workers (all Nutritionists) collected all types of data. Weight and height status were determined and laboratory techniques were used to determine, Afrikaans: Beskikbare literatuur beklemtoon die belangrikheid van voedselveiligheid in die verkryging van gekoördineerde en betekenisvolle resultate van voedsel - en voedingsekuriteit. Sodoende kan intervensieprogramme verbeter word en vordering in die verkryging van voedselsekerheid in huishoudings bewerkstellig word. Die studie is onderneem met die doel om moontlike indikatore van voedselveiligheid te ondersoek wat moontlik kan bydra tot verbeterde bepaling van huishoudelike voedselsekerheid (HVS) in die plattelandse Vhembe distrik, Limpopo Provinsie, Suid Afrika. Die sub-doelwitte was om HVS en huishoudelike voedselveiligheid, asook die verwantskap tussen indikatore van HVS en voedselveiligheid te bepaal en om voedselveiligheidindikatore van HVS te ontwikkel. ‘n Dwarssnit studie is onderneem. Van die 299 klein statte in die Thulamela munisipaliteit van die Vhembe Distrik is 29 ewekansig gekies. Van die 29 gekose klein statte is 4 trosse van klein statte volgens elk se bevolkingsgrootte gevorm. Sodoende is huishoudings in verhouding en ewekansig uit die gekose klein statte gekies. Die finale ewekansige steekproef het 335 huishoudings met ten minste een kind (3-5 jaar) en ‘n oppasser ingesluit. Die oppasser kon die ma van die kind of enige ander oppasser bo 18 jaar wees wat die meeste verantwoordelik was vir die voedselbereiding in die huishouding. ‘n Gestruktureerde onderhoudskedule is gebruik, bestaande uit vraelyste en data/rekord kaarte wat tydens ‘n onderhoud met die respondent van elke huishouding voltooi is. ‘n Sosiodemografiese vraelys; ‘n voedselbeskikbaarheid en – toeganklikheid vraelys; ‘n voedselinventaris; ‘n agt-item hongerskaal; ‘n voedselfrekwensie vraelys; ‘n voedselhanteringspraktyke vraelys en ‘n voedselhanteringskennis toets; ‘n 24 uur herroep en ‘n kindergesondheidststus vraelys; asook rekordkaarte is ingesluit. Vyf herhaaldelik opgeleide (vir ooreenstemmigheid) veldwerkers (almal voedingkundiges) het al die data versamel. Massa en lengte statu, National Research Foundation (NRF)

Fermentation has been used for over three thousand years as an effective and inexpensive means to preserve the quality and safety of foods. In Africa most of the traditional foods are fermented at household level before consumption. The cereals are fermented, and then cooked prior to consumption and this offers added safety advantages because pathogenic microorganisms are inactivated thereby increasing shelf life of product. However, some cereals are cooked first and then other sources of fermentable carbohydrates and amylase such as other cereals (malts) or roots from Rhynchosia spp. (generally called munkoyo roots) are added and then fermented prior to consumption. Chibwantu and munkoyo beverages, Zambia‟s important cereal based fermented foods are prepared in such a way. The substrates added after cooking of cereals are a major concern in terms of product quality and safety. In literature there is limited information on munkoyo roots. Knowledge on quality of these roots, their effect on quality and microbiological safety of the fermented food products prepared by their use is essential for the development of improved products for increased consumption, commercial production and marketing. The present research work aimed at contributing to closing up this knowledge gap by evaluating the microbiological quality and safety of chibwantu. This was done by first gathering information on the production and utilisation of indigenous cereal based fermented food products in Lusaka and Chongwe districts of Lusaka province, Zambia with special emphasis on chibwantu and munkoyo beverages prepared using munkoyo roots. Second to isolate and characterize the microorganisms associated with the munkoyo roots and maize grit used during the preparation of chibwantu and to establish whether the same microorganisms are involved during the fermentation process of the beverage. Third to study the survival of selected food borne enteropathogenic microorganisms during fermentation of chib, Organization for Women in Science for the Developing World (OWSD)

English: Fermented foods contain essential nutrients needed to maintain optimum health as well as other components that help in the delaying and prevention of diseases such as chronic illnesses. Indigenous naturally fermented milk of different regions in Africa play an important role in their daily diet and it helps rural woman to generate a household income. The literature review focused on the microbial composition of fermented milk in different regions in Africa (Botswana, Lesotho, Namibia and Swaziland). Furthermore, the positive and negative interactions associated with fermented milk were discussed in detail. Fermented milk is the result of the activity of a group of microorganisms. Each of these organisms plays an important role in the production of the final fermented product. Before fermentation, undesired microorganisms were present in the samples, but after a four day fermentation the yeasts and lactic acid bacteria (LAB) interactions created an environment impossible for pathogens to survive. The yeasts provide essential growth compounds for the starter culture (LAB) but remained at low numbers at the end of fermentation because of being outcompeted by faster growing LAB. The dominant LAB of the different regions was determined by DGGE and culture sequencing. Enterococci and Lactoccoci were found to be the dominant LAB followed by Leuconostocs and Streptococci. Enterococcus durans species comprised 32% of the isolated LAB. The microbial composition has beneficial effects not only for the consumer but may assist in the improvement of the final product. The microbial interaction between dominant LAB and yeasts frequently observed in dairy products was also monitored during a study in Lesotho. During the growth studies the LAB in combination with the yeasts had a much better growth rate, but in contrast the yeasts grew better on its own compared to those in combination with LAB. For the change in chemical composition it was also found that if in co-culture, Afrikaans: Gefermenteerde voedsel besit belangrike nutriente wat nodig is vir 'n optimal gesondheid, dit besit ook ander komponente wat help in vertraaging en voorkoming van kronies siektes. Inheemse natuurlike gefermenteerde melk van verskillende gebiede in Afrika speel 'n belangrike rol in die daaglikse diet en help landelike vrouens om 'n huislike inkomste by te dra. Die literatuur oorsig fokus op die mikrobiese komposisie van gefermenteerde melk in verskillende gebiede in Afrika (Botswana, Lesotho, Namibia en Swaziland). Die positiewe en negatiewe interaksies geassosieer met gefermenteerde melk word ook volledig bespreek. Gefermenteerde melk is die resultaat van die aktiwiteite van 'n groep mikroörganismise. Elk van die organismis speel 'n belangrike rol in die vervaardiging van die finale gefermenteerde projek. Voor fermentasie kom onplesierige mikroörganismis voor in die produk, maar na fermentasie vorm die giste en melksuurbakterieë 'n omgewing wat dit onmoontlik maak vir patogene om te oorleef. Die giste voorsien vir die begin kultuur (melksuurbakterieë), maar aan die einde van fermentasie kom die giste slegs voor in lae getalle as gevolg van die melksuurbakterieë wat vinniger groei. Die dominante melksuurbakterieë van die verskillende gebiede was bepaal deur DGGE en kultuur basispaaropeenvolgingbepalings. Enterococci en Lactococci was die dominante melksuurbakterieë gevolg deur Leuconostocs en Streptococci. Enterococcus durans spesies bestaan uit 32% van die geïsoleerde melksuurbakterieë. Die mikrobiese samestelling het 'n voordelige effek nie net vir die verbruiker nie maar help ook in die bevordering van die finale produk. Die mikrobiese interaksies tussen die dominante melksuurbakterieë en die giste wat gereeld gevind word in suiwel produkte is ook gemonitor. Tydens die groei studies van die melksuurbakterieë in kombinasie met die giste het die melksuurbakterieë 'n baie beter groei tempo, maar in kontras the giste groei beter op hulle eie as in kombinasi, National Research Foundation (NRF)

A literature review on the role and presence of microorganisms in cheese was reviewed. The biochemical pathways involved in the cheese manufacture from the milk to the resultant cheese curd at the end of manufacturing were also reviewed. The activity of microorganisms used in cheese manufacture and microorganisms isolated from cheeses were also discussed and their role in the cheese curd formation. Yeasts, one of the microorganisms isolated from cheeses, were reviewed in detail. The use of yeasts as adjunct starter cultures in matured Cheddar cheese was investigated. The yeast cultures (Yarrowia lipolytica, Debaryomyces hansenii, Torulaspora delbrueckii and Dekkera bruxellensis) were inoculated in milk for the manufacture of matured Cheddar cheese as adjunct starter cultures. The yeast cultures supported the role of the starter culture (LAB) – lactose fermentation, and assimilated the organic acids present and inhibited spoilage microorganisms. The growth of the yeast and LAB was mutualistic in all the cheeses and no defects were detected in the cheeses as observed by the favourable sensory scores for the yeast inoculated cheeses. Co-inoculation of yeasts in the making of matured Cheddar cheese resulted in enhanced survival of the yeasts and the LAB population in the cheeses. The yeasts exhibited increased growth, without suppressing the viability and activity of LAB. Organic acids which are associated with aroma and flavour compound production were increased in the cheeses. The cheese inoculated with Dekkera bruxellensis + Yarrowia lipolytica had superior Cheddar cheese scores which were greater than 5 as well as the cheese single inoculated with Dekkera bruxellensis. The pH measurements of the cheeses indicated the deacidification abilities of the yeasts and the spoilage inhibiting acidity in the cheeses. Free amino acid accumulation in cheeses was also investigated. It was observed that the yeast inoculated cheeses had greater free amino acid accumulation compare, National Research Fund (NRF)

English: The history and the background of dairy products, specifically fermented milk products and foodborne diseases were reviewed. The constructed literature review also gave details of the microbial and nutritional compostion of fermented milks and examples of African traditional fermented milks. Health benefits of these dairy products were also included. Furthermore, the most common foodborne pathogens and their survival in dairy products were discussed. The survival of Escherichia coli O157:H7, non pathogenic Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Salmonella spp. and Shigella spp in plain and fruit yoghurt during cold storage at 4 °C was investigated. The survival of these microbial pathogens ranged between 1-14 days in both types of yoghurt, with Staphylococcus aures being the most sensitive pathogen to the yoghurt enviroment. Lactic acid bacteria and yeasts counts remained fairly stable at an average of 8 log cfuml-1 and below 10cfuml-1 respectively. A reduction in pH was noticed during yoghurt storage. The high numbers of LAB and low pH played a major role in the inhibition of the food borne pathogens over time in both plain and fruit yoghurt. The survival of the same microbial pathogens in fruit yoghurt during temperature abuse at 25°C was investigated. There was a rapid die-off of the food borne pathogens at this temperature. Their survival in the yoghurt ranged between 1-3 days. There was a rapid decrease in pH and an increase in the LAB and these together with the high temperature played a major role in the higher death rate of the foodborne pathogens in the fruit yoghurt. Yeasts grew to high levels that caused the yoghurt to spoil. When comparing yoghurt stored at 4 °C and 25°C a conclusion was made: yoghurt stored at 4 °C will be of good quality but will not be regarded as safe as pathogens survival for a long period, and yoghurt stored at 25°C will be regarded as safe but will not be of good quality as high yeasts counts wil, National Research Foundation (NRF)

Several aspects related to cereal fermentations were reviewed in the literature section of this study. These aspects included among others, the history of indigenous cereal fermentation, factors that affect cereal fermentation, potential microbiological hazards of cereal fermentation, recent advances in related industry, and the future of fermented foods. A wide variety of recipes exists across the African continent and the beers are known by many local names. In particular this study focussed on mahewu and umqombothi, both made from a combination of maize and sorghum, fermented beverages consumed in South Africa. Improved process technologies such as the use of starter cultures can lead to improved product characteristics and consequently better health attributes for the consumer of these indigenously fermented products. During the fermentation processes for umqombothi and mahewu, yeasts, lactic acid bacteria, moulds and enterobacteriaceae were present at the start of the process but as fermentation progressed yeasts and lactic acid bacteria were the dominant microorganisms. This was over a 48 h, and 3 day, fermentation period for the umqombothi and mahewu respectively. Home-, township-, and laboratorymade samples of umqobothi were compared while for mahewu, the comparison was between the home- and laboratory-made samples. Results from different production sites were not significantly different although there were instances that called for improved hygiene as contaminants were found in some samples. Yeasts isolated from umqombothi were identified and these included; Candida ethanolica, C. haemuloni, C. sorbophila, Dekkera anomala, Dekkera bruxellensis, Saccharomycopsis capsularis and Saccharomyces cerevisiae. The yeasts isolated from mahewu were identified and the predominant strains were Candida haemuloni, Candida sorbophila, Debaryomyces hansenii, Saccharomyces capsularis and Saccharomyces cerevisiae. Confirmation of the yeast identity was done using sequence ana

From the extensive literature review given in Chapter 1, it is evident that milk is an important part of the diet and can also serve as a good medium for growth of microorganisms. These microorganisms can be either pathogenic or being undesired causing spoilage. The pathogenicity and incidence of undesired microorganisms were reviewed and as a result one of the aims of this study was to assess the hygienic quality of milk sold in and around Bloemfontein. The results obtained during this study proved interesting as it showed an alarming high percentage of these milk samples were of a poor microbial quality as they did not confirm to the National Legislation regarding milk sold to consumers. The importance of yeasts in the dairy industry has been highlighted on a number of occasions by various authors. Despite indications of yeasts associated with dairy products, especially in yoghurts and cheeses, and milk being the raw material of these products, surprisingly few studies have been conducted on the specific occurrence of yeasts in either raw or pasteurized milk. The results obtained showed an ability of these yeasts to survive and proliferate in both raw and pasteurized milk. However, the number of yeast cells was low and insignificant to cause major problems. A wide diversity, including 14 different species was isolated and characterized. The alarming effect remains that predominant species like Candida albicans was found, a severe human pathogen. Due to concerns that some potentially dangerous and high numbers of undesired microorganisms may derive from the dairy farm, the ability to efficiently control these populations at the farm level seemed desirable. Consequently, the effect of ultraviolet irradiation on the microbial loads and chemical composition of raw milk was investigated. The results showed a 90% reduction on the microbial populations, except yeast numbers showing more resistance being reduced by 73%. Chemical analysis compared from results performed be

A literature review regarding the properties of probiotic bacteria were discussed including their therapeutic value, the survival in bio-products and the expansion of the probiotic food range. Cheese offers certain advantages as delivery system for live probiotic bacteria to the human gastro-intestinal tract. Furthermore, the enumeration of probiotics in functional foods was discussed, with special reference made to enumeration media. Probiotic regulations were also discussed, with an in-dept look at regulatory platforms world wide as well as regulations regarding administration levels. Normal practise in the manufacturing of functional food products, is to incorporate the slow growing probiotic cultures, containing beneficial effects, with the fast growing lactic acid bacterial starter cultures, which aid in the speed of the fermentation process. An important parameter in monitoring official levels of viable probiotics, is the ability to count probiotic bacteria differentially, however great controversy exists regarding administration levels as well as standard enumeration media. Nine bacteriological media were subsequently evaluated to assess their suitability and to selectively enumerate L. rhamnosus strain HN001 (DR20TM), in the presence of other lactic acid starter bacteria in South African matured Cheddar cheese. Differences in recovery between the different media as well as the interaction between the media and the availability of oxygen were investigated. MRS-V and BA-R(20%)V agar were ranked as the superior media, while MRS-V agar and aerobic incubation conditions at 43oC for 48h proved to be the most selective medium to enumerate L. rhamnosus in the presence of other cheese starter cultures. Predictive modeling may contribute to a better understanding of and control of microbial processes, and help to clarify in which manner, and to which degree, the food environment will interfere with the functionality of the probiotic strains used. At environmental cond, National Research Foundation (NRF)

The microbial ecology of Sethemi is complex and determines its quality and safety. Raw milk and Sethemi (a naturally fermented milk from South Africa) samples were collected in the vicinity of Bloemfontein, South Africa, to determine the development and diversity of all relevant microorganisms. Simulated milk fermentations were executed in the laboratory to study environmental influences on the microbial development. A total of 116 yeasts were isolated and identified using conventional methods and sequence analysis of the D1/D2 domain. The isolates belonged to 12 different genera and 22 distinct species. Despite the high diversity during the initial stages of fermentation, only seven species proved to be dominant at all stages being present at high numbers in the final product. The predominant species were identified as C. albicans, Cryptococcus curvatus, Debaryomyces hansenii, Kluyveromyces marxianus, Clavispora lusitaniae, Saccharomyces cerevisiae and Yarrowia lipolytica. Aerobic mesophilic bacteria, lactobacilli-leuconostocs and lactococci being present at numbers in excess of 9 log10 CFU/ml, however, predominated during processing and in the final product. Sethemi was also produced in the laboratory in four different containers, namely clay pot, gourd, nickel jar and plastic jar, using the traditional methods of milk fermentation. The development of bacteria and yeasts was similar in all containers but differed in the time to reach maximum numbers. Optimum growth of LAB was obtained sooner in nickel containers. The highest yeast diversity was, however, obtained in the clay pot dominated by the yeasts Deb. hansenii, Cr. humicola and K. marxianus, which were commonly found in the raw and naturally fermented milks. Considering their industrial or health importance, four dominant yeast species, namely K. marxianus, S. cerevisiae, C. albicans, and Deb. hansenii were selected for environmental studies. S. cerevisiae showed the highest stimulatory effect on the growth

English: Approximately 100 000 tonnes of edible frying oil and fat waste, mainly derived from sunflower oil, is produced each year from the estimated 54 000 frying establishments in South Africa. Many of these establishments overuse or abuse their oils to save money. Such practices may result in oil breakdown and the production of harmful compounds, which can cause diseases such as cancer and diarrhoea when consumed. As a result, approximately 30 % of frying oil and fat waste in S.A. can be regarded as unhealthy while the other can be considered still useful for human consumption containing within S.A. regulatory limits i.e. equal to or less than 16 % polymerised triglycerides (PTGs) and/or equal to or less than 25 % polar compounds (PCs). In order to ensure that only oils and fats fit for human consumption are used during frying processes in S.A., it is important that sound quality control procedures are applied to all sectors of the oil industry. This is of special significance when taking into consideration the numerous cases of frying oil misrepresentations, adulteration and overuse reported over the years in S.A. The approximately 70 % of oil wastes still within the regulatory limits have the potential to be processed to safe usable foodstuffs such as Evening Primrose Oil equivalents (EPOeq). Evening Primrose Oil (EPO) has received attention over years as a medicinal supplement due to its high content of gamma-linolenic acid (GLA). A wellknown fact is that the positional distribution of GLA on the glycerol moiety of triacylglycerols has an effect on its functional properties as well as metabolism. When Mucor circinelloides f. circinelloides CBS 108.16 was cultivated on a mixed substrate of sunflower oil (30 g/l) containing 1 %, 5 %, 10 %, 15 % and 45 % (w/w) PTGs and sodium acetate (10 g/l) as carbon sources, most of the oil was utilized after seven days of growth. Marked increases in biomass production as well as in the lipid content of the fungal cells were a, Afrikaans: Ongeveer 100 000 ton eetbare kookolie- en vetafval, hoofsaaklik afkomstig vanaf sonneblomolie, word elke jaar geproduseer deur ongeveer 54 000 braairestaurante in Suid-Afrika. Baie van hierdie restaurante oorgebruik of misbruik hulle olie om geld te spaar. Sulke praktyke veroorsaak olie-afbraak en die produksie van skadelik verbindings wat siektes soos kanker en diaree kan veroorsaak as dit ingeneem word. Dus kan ongeveer 30 % van kookolie- en vetafval in S.A. beskou word as skadelik terwyl die res gesien kan word as bruikbaar vir menslike gebruik aangesien dit steeds binne die S.A. regulatoriese limiete val, d.i. gelyk aan of minder as 16 % gepolimeriseerde trigliseriede (PTGs) en/of gelyk aan of minder as 25 % polêre komponente (PKs). Om te verseker dat slegs olies en vette wat geskik is vir menslike gebruik in braaiprosesse in S.A. gebruik word, is dit belangrik dat goeie kwaliteitsbeheerprosedures in alle afdelings van die olieindustrie toegepas word. Dit is veral belangrik as die verskeie gevalle van kookoliewanvoorstelling, -vermenging en oorgebruik wat oor die jare in S.A. gerapporteer is, inaggeneem word. Die ongeveer 70 % olie-afval wat steeds binne limiete is, het die potensiaal om na veilige, bruikbare voedingstowwe soos Aandblomolieekwivalente (AOekw) verwerk te word. Aandblomolie (AO) het oor die jare baie aandag geniet as ‘n mediese aanvulling as gevolg van ‘n hoë gamma-linoleensuur (GLS) inhoud. Dis bekend dat die posisionele verspreiding van GLS op die gliseroleenheid van triasielgliserole ‘n effek het op die funksionele eienskappe en metabolisme. Mucor circinelloides f. circinelloides CBS 108.16 is gekweek in gemengde media met sonneblomolie (30g/l) wat 1 %, 5 %, 10 %, 15 % of 45 % (m/m) PTGs bevat het, asook natriumasetaat (10g/l) as koolstofbronne. Meeste van die olie is gebruik na sewe dae van groei. Merkbare toenames in biomassaproduksie asook lipiedinhoud van fungiselle is opgemerk. Die sonneblomolies is getransformeer na fungi-olies, National Research Foundation (NRF), Andrew Mellon Foundation

From the extensive literature review given in Chapter 1, it was evident that blue-mould cheeses are unique in terms of the flavour, aroma, texture and microbial developments that take place during production and maturation. Despite surface mould-ripened cheeses only representing a small portion of the annual world cheese production, their popularity is increasing worldwide making it important to study their microbiological, biochemical and technological properties. Consequently, the aims of this study were to identify a medium suitable for the isolation and enumeration of yeasts in the presence of moulds, elicit the establishment, growth and survival of yeasts during the processing and ripening of blue-mould cheeses, to follow the interaction between the microbiota present and to determine their influence on each other. In addition, since the interactive development of the different microbiota also affects the final cheese product, the technological changes were determined. As Brevibacterium linens plays a substantial role on the quality of blue veined cheese, various methods were applied as a means of inhibiting the growth and development of the species. The enumeration of yeasts in the presence of moulds proved to be difficult since the yeasts are easily overgrown by the rapid spreading of moulds. We therefore aimed to find a medium that not only supported the growth of the yeasts, but also inhibited mould growth to such an extent that the isolation and enumeration of the yeasts could be performed with relative ease. Ten different selective media with anti-mycotic properties were evaluated and compared statistically using analysis of variance (ANOVA) and the TukeyKramer multiple comparison test, for their ability to suppress the growth and spreading of moulds and to enhance the enumeration and recovery of yeasts from blue-mould cheeses. No significant differences in quantitative data obtained on Rose-Bengal Chloramphenicol Agar (RBCA), Dichloran RoseBengal Chloram, National Research Foundation (NRF)

A literature review dealing with various aspects of cheesemaking and ripening is given in Chapter 1. With respect to starter cultures, the criteria for strain selection as well as the taxonomy of different starter strains were discussed. Cheese ripening is a complex system that involves numerous chemical, physical and bacteriological changes and can be accelerated by various techniques. Special reference was made to yeasts associated with dairy products, their characteristics as well as their contribution in the dairy industry. Yeasts play a very important role in the ripening and manufacturing of a wide variety of cheeses and can cause spoilage or have beneficial effects on cheese ripening. Furthermore, the properties of probiotic bacteria were discussed including their therapeutic value, their survival in bio-products and the possible expansion of the probiotic product range. Cheese offers certain advantages as a delivery system for live probiotic bacteria to the human gastro-intestinal tract. Debaryomyces hansenii and Yarrowia lipolytica are typical foodborne yeast species frequently associated with dairy products and capable of predominating the yeast composition in such systems. The two species fulfil a number of criteria to be regarded as co-starters for cheese making. They are known for their proteolytic and lipolytic activity as well as their compatibility and stimulating action with the lactic acid starter cultures when co-inoculated. Recent studies indicated that yeasts could be included as part of starter cultures for the manufacturing of cheese, enhancing flavour development during the maturation. The potential of D. hansenii and Y. lipolytica as agents for accelerated ripening of matured Cheddar cheese has been evaluated during four cheese treatments. The interaction between the two yeast species and the lactic acid bacteria was surveyed incorporating (i) D. hansenii, (ii) Y. lipolytica and (iii) both species as adjuncts to the starter culture and (iv)

English: Increased media and public interest over meat contamination have highlighted the need for continual improvements in this regard in the poultry industry. In spite of all the effort and money placed into research on microbial contamination of poultry carcasses, it is still not possible to produce carcasses, which are free of spoilage and pathogenic microorganisms. Carcasses are mostly contaminated during processing, contributing to the presence of high number of mesophilic microorganisms. The spoilage microorganisms cause consumers to reject the product due to appearance, off odour or undesirable flavour whereas the pathogenic microorganisms may lead to health hazards. The Standard plate counts methods have been the method of choice for the enumeration of contaminating microbial populations in the poultry industry. However, these methods are laborious and time consuming. In this study, optical density (OD) reading as a microbial enumeration method on poultry carcasses was established and evaluated for its application as a rapid, alternative method. In chapter 2, the dominant microorganisms were isolated and identified from eviscerated poultry carcasses. The carcasses were sampled by whole carcass rinse method and bacteria were isolated on Plate Count Agar at 27oC for 48 h. A total of five different species were identified, based on their prevalence in the sample and were identified by conventional methods. The identification of the isolates was further confirmed by API techniques. The dominant species were Escherichia coli, Shewanella putrefaciens, Aeromonas hydrophila, Serratia marcescens and Staphylococcus aureus. Mean counts (log10 cfu/g) of these organisms were 3.08, 1.48, 0.85, 1.74, and 1.21 respectively. In chapter 3, OD readings as an enumeration method was established. This required the establishment of a number of parameters, which include: 1) Determining the wavelength to be used throughout this study. This achieved by scanning the medium through t, Afrikaans: Toenemende belangstelling deur die media en publiek na vleis-kontaminasie het die nodigheid vir toenemende verbetering in hierdie verband in die pluimvee industrie aan die lig gebring. Ten spyte van al die moeite en geld aan navorsing na mikrobiese kontaminasie van pluimvee karkasse is dit steeds nie moontlik om karkasse, vry van bederf en patogeniese mikroörganismes, te produseer nie. Karkasse word meestal gekontamineer gedurende die ontwikkeling, wat bydra tot die teenwoordigheid van hoë getalle mesofiliese mikroörganisme. Die bederf mikroörganismes veroorsaak dat verbruikers die produk verwerp weens voorkoms, af-reuke of onaanvaarbare geur, waar patogeniese mikroörganismes kan lei tot gesondheidsgevare. Die standaard plaat-telling metodes was die metode van keuse vir die bepaling van kontamininerende mikrobe populasies in die pluimvee industrie. Maar hierdie metode is arbeid intensief en tydrowend. In hierdie studie is optiese digheidslesings (OD) as ‘n mikrobiese bepaling metode op pluimvee karkasse ontwikkel en geëvalueer as ‘n vinnige alternatiewe metode. In hoofstuk 2, is die dominante mikroörganismes geïsoleer en identifiseer uit geslagte pluimvee karkasse. Monsters is geneem vanaf karkasse deur die heel karkas-spoel metode en die bakterieë is geïsoleer op “plate count agar” (PCA) by 37oC vir 24 uur, ‘n totaal van vyf verskillende spesies is geselekteer, gebaseer op voorkoms in die monster en is geïdentifiseer deur konvensionele metodes. Die identifikasie van die isolate is verder bevestig deur API tegnieke. Die dominante spesies was Escherichia coli, Shewanella putrefaciens, Aeromonas hydrophila, Serratia marcescens en Staphylococcus aureus. Die gemiddelde tellings (log10 cfu/g) van hierdie mikroörganismes was 3.08, 1.48, 0.85, 1.74, en 1.21 respektiewelik. In hoofstuk 3, is die OD lesings as bepalings metode ontwikkel. Dit was dus nodig om ‘n aantal parameters vas te stel: 1) Bepaling van die golflengte wat deur die studie gebruik is. Dit is ged

English: Blue veined cheese is considered a speciality cheese and is not as popular as other cheese varieties, such as Cheddar or Gouda. Their popularity is however increasing worldwide making it important to study their microbiological, biochemical and technological properties. The aims of this study was consequently to elicit the establishment, growth and survival of yeasts during the ripening of blue veined cheese varieties and to study the interactions between yeasts and the different microbial groups which occur during the ripening process. The enumeration of yeasts in foodstuffs with a high mould concentration proves to be difficult since yeasts are easily overgrown by the rapidly spreading moulds. This makes the enumeration, isolation and identification of yeasts difficult, hence also eliciting the ecological role of yeasts during the ripening of blue veined cheese varieties. Ten different selective media, containing anti-myctotic properties, were evaluated for their ability to suppress the growth and spreading of moulds and enhance the enumeration and recovery of yeasts from blue veined cheese. Quantitatively no statistical difference between the ten different media was detected. Qualitatively, however OGGY, MEA + SP and molybdate containing media could not be recommended. All other media performed satisfactory while MEA + Ox and MEA + BP gave superior results based on ease of isolation and enumeration. The usage of MEA + NaCl gave comparable results, but inhibited the growth of some of the yeast species most frequently found in ripening blue veined cheese varieties, when evaluated individually. Yeasts are one of the main microbial groups that occur during the ripening of blue veined cheese varieties, originating as post-pasteurisation contaminants. In chapter 3 the development of yeasts derived mainly from the dairy environment and their establishment during the ripening process was examined. They continued to dominate until the end of the ripening period, Afrikaans: Blou kaas variante word as ‘n spesialiteits kaas beskou en is derhalwe nie so gewild soos ander variante, byvoorbeeld Gouda en Cheddar. Die gewildheid van die tipe kase neem egter wêreldwyd toe. Om dié rede is dit dus belangrik om die mikrobiologiese, biochemiese en tegnologiese aspekte van die kase te bestudeer. Die doel van die studie was om die ontstaan, groei en oorlewing van giste tydens die rypwordingsproses van blou kaas variante te bestudeer, asook die interaksies wat plaasvind tussen die verkillende mikrobiese groepe tydens rypwording. Die optelling van giste in voedsel met ‘n hoë konsentrasie skimmels is moeilik aangesien die skimmels die giste oorgroei. Dit maak die optelling, isolasie en identifikasie van giste moeilik en gevolglik ook die bestudering van die ekologiese rol van giste tydens die rypwording van blou kaas variante. Tien verskillende selektiewe media wat anti-mikotiese middels bevat is getoets vir hul vermoë om die groei en verspreiding van skimmels te inhibeer. Hulle is ook getoets vir hul vermoë om te help met die optelling en isolasie van giste vanaf die blou kaas variante. Kwantitatief was daar geen statistiese verskil tussen die tien selektiewe media. Volgens kwalitatiewe data kon OGGY, MEA + SP en molibdaat bevatende media nie aanbeveel word nie. Al die ander media het bevredigend vertoon. MEA + Ox en MEA + BP het die beste resultate gelewer gebasseer op die feit dat isolasie en optelling vergemaklik was. MEA + NaCl het eenderse resultate getoon maar het die groei van sekere individuele gis spesies wat mees algemeen in blou kaas variante voorkom geinhibeer. Giste vorm een van die hoof mikrobiese groepe wat voorkom tydens die rypwording van blou kaas variante en ontstaan as post-pasteurisasie kontaminante. In hoofstuk 3 is die ontstaan en ontwikkeling van giste uit die omgewing bestudeer. Gis spesies wat geisoleer en geidentifiseer is stem ooreen met die wat verkry is deur ander navorsers op soortgelyke blou kaas variante. ‘n

Surface mould-ripened cheeses represent a small proportion of world cheese production. However, these cheeses are becoming increasingly popular with the consumer, as there is an increasing demand for it (Gripon, 1987). In Chapter 1 the integrated roles of moulds, yeasts and bacteria involved in the production and maturation of white surface mould-ripened cheeses, and the assistance of the microflora in the development of the characteristic flavour and texture of mould-ripened cheeses, were thoroughly discussed. Due to the fact that yeast colonies are often overgrown by mould spreaders, we intended to develop a medium that inhibits moulds and bacteria, but supports the growth of all yeasts present in white-mould cheeses. Ten selective mycological media were evaluated and compared statistically for their suitability to enumerate yeasts and simultaneously suppress moulds in white-moulds cheeses. Malt extract agar (MEA) supplemented with 0.5% sodium propionate (SP), proved to be the only medium that totally suppressed mould growth. However, the medium also restricted yeast development, as the mean yeast counts obtained on this medium differed significantly (p<0.5) compared to the other media. Dichloran Rose Bengal agar (DRBC) and Oxytetracyline Gentamycin Glucose Yeast Extract agar (OGGYA) retarded mould growth and supported the growth of the six most dominant yeast species recovered from white-mould cheeses, making these media suitable for the isolation and enumeration of yeasts in the presence of moulds. The yeasts present in Camembert and Brie cheeses during processing were monitored in a single cheese factory during summer and winter, to determine the seasonal diversity of yeasts over a ripening period of 56 days. Despite the predominance of lactic acid bacteria during the making of Camembert and Brie, yeasts playa significant role in the ripening process reaching counts as high as 106 cfu.q' at the later stages of ripening. A diverse variety of 20 yeast species rep, National Research Foundation (NRF)

English: Techniques to maintain and preserve microorganisms have become important to ensure availability of microorganisms for application in many institutions and processes. Several methods are available to preserve microorganisms and include drying, lyophilization, cryopreservation and sub-culturing. Many of these methods, may lead to population change through selection, loss of viability as well as poor survival rates when used for maintenance of yeasts. In this study, different preservation methods (cryopreservation at -196°C in liquid nitrogen, freezing at -70°C and lyophilization) were compared in the maintenance of brewing inocula over a period of two years. Interestingly, a decrease in the percentage of variants and respiratory deficient yeasts (RDs) was generally found when preserved through cryopreservation (-196°C) and freezing (-70°C). In contrast, the percentage variants when revived yeasts were grown in wort, increased in yeasts maintained through lyophilization. A high percentage viable cells (>95%) was recorded for yeast cultures maintained at -196°C and at -70°C while viability was low (<50%) when maintained through lyophilization. Consequently, the maintenance methods of choice are cryopreservation and freezing. The developed cryopreservation method was successfully implemented in the brewing process that produced the champion lager beer "Castle Lager" at Burton-upon-Trent in the UK (April; 2000). The results of the estimate of the components of variance showed that the largest source of variation in all three of the methods tested, was the error arising from the analytical test. On the basis of these results, it , subsequently became another aim of this study to explore alternative analytical tests to differentiate and characterise yeasts in the brewing industry. Consequently, PCR based RFLP, fatty acid and sterol profiles were evaluated. Using PCR based RFLP, a study to differentiate brewing yeasts from related yeasts using amplification and rest, Afrikaans: Tegnieke vir die bewaring van mikrobes is belangrik ten einde die beskikbaarheid van mikrobes vir aanwending in verskeie instansies en prosesse te verseker. Verskeie metodes vir die bewaring van mikrobes is beskikbaar en sluit in droging, vriesdroging, 'vries en die maak van subkulture. As hierdie metodes gebruik word vir die bewaring van giste, mag van hulle lei tot veranderinge in die populasie a.g.v. seleksie, verlies aan lewensvatbaarheid en lae oorlewingsvlakke. In hierdie studie is verskillende bewaringsmetodes (vries by (-196°Cin vloeibare stikstof, vries by -70°C en vriesdroging) vergelyk oor 'n tydperk van twee jaar in die bewaring van brou-inokula. Oor die algemeen is 'n afname in variante en respiratories-gebrekkige giste gevind as bewaring d.m.v. vriesing (-196°C en -70°C) gedoen is. In teenstelling, het die persentasie variante toegeneem as gevriesdroogde giste weer in moutekstrak opgegroei is. 'n Hoë persentasie lewensvatbare selle (>95%) is waargeneem in giskulture bewaar by -196°C en -70°C, terwyl lewensvatbaarheid laag was <50%) in gevriesdroogde kulture. Gevolglik is die beste bewaringsmetodes vriesing. Die ontwikkelde vriesingsmetodes is suksesvol geïmplementeer in die brouproses wat gelei het tot die produksie en kroning van die kampioen lager "Castle lager" by Burton-upon-Trent in die VK (April, 2000). Die resultate van die berekening van variasiekomponente het getoon dat die grootste bron van variasie in al drie die getoetste metodes, die fout a.g.v. die analitiese metode was. Op grond van hierdie resultate, het dit 'n verdere doel van die studie geword om ondersoek in te stel na alternatiewe analitiese metodes om giste in die brou-industrie te differensieer en te karakteriseer. Gevolglik is PKR gebaseerde RFLP, vetsuur- en sterolprofiele geëvalueer. Met behulp van 'n PKR gebaseerde RFLP, is 'n studie uitgevoer om brouersgiste van verwante giste te onderskei m.b.V. amplifisering en beperkings-polimorfisme van die ITS areas. Onderskei

English: Currently, fruits and vegetables suffer significant losses from fungal diseases after harvest. The use of synthetic fungicides which pose a risk to human health and the environment, have resulted in an intensive search for safer control of postharvest diseases by the use of microorganisms, particularly yeasts, occurring naturally on the surfaces of fruits and vegetables. An ecological survey was preformed on five different fruit and vegetable commodities to determine the diversity of yeast species associated with these commodities and the cause of spoilage at different temperatures. A. THE INCIDENCE OF YEASTS ASSOCIA TED WITH FRUITS AND VEGETABLES. Different fruits and vegetables were surveyed to determine the diversity of yeasts and to differentiate between yeasts found on the surface and inner layer of the different fruit and vegetable commodities. Bacterial growth dominated on the surface of vegetables due to factors such as higher water content, more neutral pH and close proximity to the soil facilitating their growth. Yeasts represented the major component of the microflora on the surface of fruits due to a lower pH and higher carbohydrate content that encouraged their growth. The inner layer of both fruits and vegetables yielded lower microbial counts. Schizosaccharomyces pombe and Debaryomyces hansenii were the predominant species isolated on both fruits and vegetables. Spoilage of fresh fruits usually results from the fermentative activity of yeasts, but no such species were isolated during this study. B. THE GROWTH AND SURVIVAL OF YEASTS IN FRUITS AND VEGETABLES STORED AT DIFFERENT TEMPERATURES. The growth and survival of yeasts were carried out at different temperatures over a 30- day period to determine an epiphytic yeast population developing on the surfaces of fruits and vegetables. The chemical and physical composition were monitored over a 30-day period to determine if the changes in pH and organic acids contributed to the developing yeast po

Yeasts have a competitive advantage in yoghurt due to its ability to grow at low pH values and temperatures and therefore are major role players in causing spoilage. The yeasts occurring as natural microflora in commercial yoghurt were isolated and identified according to conventional identification and enumeration techniques. Characteristics of the naturally contaminating yeasts of commercial yoghurt revealed a limited diversity of yeast species. The yeasts most frequently isolated were Kluyveromyces marxianus, Debaryomyces hansenii, Saccharomyces cerevisiae, Saccharomyces exiguus and Yarrowia lipolytica. Rhodotorula spp. occurred at a very low incidence. Since these yeasts play a substantial role in the spoilage of commercial fruit yoghurts,especially when cold storage practices are neglected, the deterioration of yoghurt samples obtained from the manufactures were evaluated at different temperatures for a period of 30 days during this study. Based on the results obtained, the interaction between the yeasts and lactic acid bacteria resulted in a decline in pH values and the stabilization of viable lactic acid bacterial loads. The highest number of yeast populations, up to 104 and 106 cfu/g, was found when yoghurts were exposed to elevated temperatures in the range of 25°C, while lower yeast counts were obtained from samples kept refrigerated at a temperature of 5°C. Populations not less than 103 cfu/ml were generally observed in commercial yoghurt samples. All the isolated yeasts were examined based on relevant key properties that governed their growth and survival in yoghurt. All the yeasts were tolerant to 4-8% NaCI, except for Saccharomyces cerevisiae, and 40 - 80 ppm nitrite. The lipolytic and proteolytic activity appeared variable. The yeasts in 60 samples of Hungarian yoghurt were enumerated and identified according to conventional methods and compared with a similar survey conducted in South Africa. The yeast counts ranged from 103 - 105 cfu/g in both count

Microorganisms, especially pathogens, play an important role in the deterioration of poultry meat and its products causing spoilage or food poisoning. The meat renders an ideal medium for the growth and progression of microorganisms originating from the environment on the farm (eggs and broiler), transport to the abattoir as well as the abattoir. As far as we know, no attempts were undertaken to determine the total microbial spectrum, including bacterial and yeast populations from the egg unto the chicken carcass after slaughtering. A historical review of the incidence and extent of microorganisms associated with poultry and it's environment is given in Chapter 1. The background of poultry production and contribution of microorganisms (for example pathogens and yeasts) are highlighted. In Chapter 2 a survey was undertaken to determine the incidence, extent and serotypes of different pathogens on and in freshly laid eggs as well as incubated eggs in the breeder broiler hatchery. In addition, the number of viable cells of bacteria and yeasts were also determined. Microbial counts on the dirty eggs predominated. A major decline in microbial numbers on the egg shells, however, were observed after 18 days in the incubator. The deduction in bacterial populations present on the egg shells after 18 days in the incubator, is ascribed to the constant fogging of the environment inside the incubator with clinafarm. The irregular gathering of eggs as well as the dirty hands of the egg collectors could have been the major contributors of the high counts on these eggs. The only pathogens obtained were Listeria and E. coli type 1.In Chapter 3 the microbial populations associated with the caecum and liver of broilers as well as with the environment were determined. Anaerobic plate counts reflecting the dominance of bacterial populations were constantly the highest ascribed to the contents of the gut. Salmonella, Staphylococcus aureus and E. coli type 1 were isolated from the caecum, Country Bird

A review of the literature highlighting the importance of the 'therapeutic minimum' and the survival of the probiotic bacteria in fermented milk bioproducts is given in Chapter 2. Special reference is made to the historical background of probiotics, its therapeutic value and the survival through passage in the gastrointestinal tract. In addition, technology of bio-yogurt, factors affecting the survival of probiotic bacteria in yogurt, and the media for the differential enumeration of these microorganisms in dairy products are discussed. In Chapter 3 existing media proposed for the selective enumeration of starter cultures employed in the manufacture of bio-yogurt are compared and evaluated. It is essential for comparison reasons to standardize enumeration methods for microbial analyses in order to study the incidence of the probiotic bacteria in the presence of the conventional starter cultures. The media proposed by Chr. Hansen's laboratory proved to be the most suitable for the enumeration of the different cultures. It is essential that bio-yogurts meet the criteria of a minimum of 106 cfu/rnl of probiotic bacteria until the expiry date to induce any potential therapeutic advantages for the consumer. Consequently, in Chapter 4 we evaluated samples of AB-yogurt obtained from supermarket outlets statistically based on the enumeration of viable probiotic cultures, Lactobacillus acidophilus and Bifidobacterium bifidum; as well as conventional yogurt starter cultures, Streptococcus thermophilus and Lactobacillus bulgaricus and the maintenance with respect to the 'therapeutic minimum'. Based on the data obtained, the AB-yogurts examined comply with the criteria regarding the number of viable cells of L. acidophilus, but the consumer would not have received sufficient numbers of B. bifidum cells at the time of consumption. In Chapter 5, we monitored the survival of viable cells of the probiotic cultures and starter cultures present in bio-yogurt at frequent intervals fro, National Research Foundation (NRF)

Afrikaans: Die verhoging in die plasing van die aantal hoenders per oppervlakte verhouding in moderne pluimvee boerdery praktyke, skep In klimaat waar mikrobiese groei (insluitend patogeniese mikroorganismes) gestimuleer word. Die stimulering van mikroorganismes word veralopgemerk in respiratories geassosieerde vrektes in groeihokke. Op grond van die verhoging in vrektes van jong kuikens is daar gekyk na die mikrobiese populasies teenwoordig in die tracheas van groeihok kuikens met spesiale karakterisering van die gis populasies teenwoordig. Die data het aangetoon dat die tracheas van jong braaikuikens hoofsaaklik besmet word deur die teenwoordigheid van gis species. Ten spyte van lae populasies in die eerste weke na uitbroeiing, ontwikkel die gispopulasies vinnig tot essensieel 'n klimaks populasie tydens die vierde week in die groeihokke. Die karakterisering van die gispopulasies het daarop gedui dat die belangrikste species blyk as volg te wees: Debaryomyces hansenii, Candida b/ankii, Toru/aspora de/brueckii en Trichosporon beige/ii. Omdat giste ook 'n belangrike bydrae maak tot die bederf van hoenderkarkasse, en deel uitmaak van die normale mikrobiologiese populasie teenwoordig op die eetbare hoenderkarkasse en hoenderstukke, is die voorkoms van hierdie flora verder deur die prosesseringsaanleg gevolg. Alhoewel giste proporsioneel in kleiner getalle voorkom as bakterieë, kan die giste as sekondêre populasie ontwikkel wanneer die bakteriese populasie geinhibeer word soos gevind nadat die karkasse onderdompel is in chloorbevattende immersie-wentelverkoelings baddens tydens prosessering. Cryptococcus en Candida species domineer voor verkoeling van die karkasse tydens ontvering en ontweiding terwyl Debaryomyces species oorheers na verkoeling en tydens bevriessing. Die data dui verder daarop dat die implementasie van chloor as ontsmettingsmiddel tydens verkoeling geen invloed gehad het op die voorkoms van die gisspecies nie. Die bronne van giskontaminasie in die onmi

Yeasts play a substantial role in the processing of salami, being present at high numbers during the ripening stages contributing to aroma and flavour development. Accordingly, the yeasts occurring as natural microflora in commercial salami were quantified, isolated and identified according to conventional identification and enumeration techniques. Depending on conditions, the yeasts grew to maximum populations of 107duIg during the ripening stages. Characterization of the naturally contaminating yeasts of commercial salami revealed 108 yeast species, belonging to 12 genera. The yeasts most frequently isolated were from the genera Debaryomyces, Rhodotorula, Bul/era, Candida, Cryptococcus, Trichosporon and Schwanniomyces in that order. Low appearances of Pichia, Galactomyces, Sporobolomyces, Sterigmatomyces and Torulaspora were observed. Debaryomyces hansenii, Rhodotorula mucilaginosa, Bul/era variabilis and Cryptococcus albidus were established as representing the typical yeast community associated with salami. These species were frequently isolated from the meat, during processing and maturation. The most frequently isolated yeast species, was D. hansenii, isolated on every sampling occasion. The isolated yeasts were examined based on relevant key properties that governed their growth and survival in fermented meat, and proposed as representative selective characteristics to determine a good starter culture. All the yeasts were tolerant to 4-8% NaCl and 80-240ppm nitrite. All the yeasts proved to be non-proteolyic with the exception of Trichosporon beigeli~ whereas lipolitic activity appeared variable. Two predominating yeast isolates, Debaryomyces hansenii and Debaryomyces polymorphus, exhibited relevant qualities regarding fermentation of meat. Consequently, they were applied in the formulation as starter cultures in an attempt to prepare a salami based on yeast fermentation. The incorporation of D. hansenii, individually, or in association with conventional star

Yeasts play an important role in dairy products causing spoilage or contribute positively to the ripening of some cheeses due to their lipolytic and proteolytic activities and the ability to grow at low temperatures, pH and water activity, and high salt concentrations. Despite various factors affecting the survival and growth of yeasts in cheese, the food commodity is considered as a potential habitat of yeasts. Cheese renders an ideal medium for the survival and progression of yeasts due to the availability of the necessary nutrients. A historical review of the incidence of yeasts, their interaction with bacteria and their properties, during the manufacturing and ripening of matured Cheddar cheese is given in Chapter 1. The history of Cheddar cheese making, the fermentation of milk during cheese making, different starter cultures and methods of application and occurrence of yeasts are highlighted. In Chapter 2 a survey was undertaken with the objective of identifying the predominant yeast contaminants associated with matured Cheddar cheese production. A total of 168 yeasts strains, representing 12 different species, isolated from matured Cheddar cheese and the immediate environment were isolated. Once the identity of the yeast flora associated with the cheese had been established, the survey was extended to determine the sources of yeast infection during the processing of the matured Cheddar cheese. The results obtained, showed that yeasts contributed substantially to the deterioration as well as the ripening of the matured cheese, especially when stored under environmental conditions exhibiting, low temperature, water activity and pH values and high salt concentrations. In Chapter 3 seven of the most dominant yeasts frequently associated with dairy products are screened for their resistance against nine commercial cleaning compounds and sanitizers commonly used in the dairy industry. None of the compounds used, however, were able to sufficiently kill the yeasts, w, Clover S. A.

English: Yeasts are widely dispersed in nature and considered as natural inhabitants of the dairy environment. They are also natural contaminants in milk and milk products causing either spoilage or leading to fermentation with beneficial effects. In kefir, yeasts belong to the typical microflora and are responsible for the prickly and refreshing taste due to carbon dioxide production. In a number of other fermented dairy products, yeasts play an important role in metabolic interactions, thereby ensuring a product with typical sensoric properties. In this study, yeasts from kefir milks fermented by seven indigenous kefir grains were isolated and characterised in order to determine the diversity of the yeast flora in South African kefir. These kefir grains were inoculated into full cream milk and incubated at 25°C tor 18 h. The fermented kefir milks revealed yeast counts between 2.00x108 and 3.00x108 cfu/ml. The representative yeast strains were dominated by Kluyveromyces marxianus, Kluyveromyces laetis and Saccharomyces cerevisiae. Other species encountered were Saccharomyces unisporus, Saccharomyces rouxii, Torulaspora delbrueckii and Debaryomyces hansenii. Furthermore, a total of 50 yeasts were isolated and identified from 14 different traditional fermented milks manufactured in households by small-scale dairy farmers in rural areas. Growth patterns and the characteristics of Kluyveromyces marxianus, Debaryomyces hansenii and Torulaspora delbrueckii, the three dominant yeast species encountered in the fermented milk samples, were determined. A commercial lactic acid bacteria (LAB) culture was used in various combinations with the yeasts in the growth and fermentation studies. Growth at different pH values suggested that these yeasts (especially T. delbrueckii) play a metabolically active role during, as well as right to the end of the lactic acid fermentation of milk. T delbrueckii also showed significant growth at 15°C, but was not able to ferment lactose, as was, Afrikaans: Giste kom wyd verspreid voor in die natuur en word algemeen in suiwel ekosisteme aangetref Giste is gevolglik natuurlike kontaminante in melk en melkprodukte wat bederf kan veroorsaak of tot voordelige fermentasie kan lei. In kefir is giste deel van die tipiese mikroflora wat verantwoordelik is vir die kenmerkende prikkelende en verfrissende smaak, a.g.v. die produksie van koolstofdioksied. In verskeie ander gefermenteerde melkprodukte speel giste 'n belangrike rol in die metaboliese interaksies waardeur verseker word dat gewenste sensoriese eienskappe ontwikkel. In hierdie studie is giste uit kefir melk, wat deur sewe verskillende kefir korrels gefermenteer is, geïsoleer en gekarakteriseer om die spesie diversiteit te bepaal. Die kefir korrels is in volroom melk geïnokuleer en vir 18 h by 25°C geïnkubeer. Gistellings van tussen 2.00x108 en 3.00x108 kolonie vormende eenhede is bepaal. Kluyveromyces marxianus, Saccharomyces cerevisiae en Kluyveromyces laetis was die mees dominante spesies, terwyl Saccharomyces unisporus, Saccharomyces rouxii, Torulaspora delbrueckii en Debaryomyces hansenii in laer getalle voorgekom het. Vyftig verteenwoordigende giste uit 14 verskillende tradisioneel-gefermenteerde suurmelk monsters, wat in huishoudings in landelike gebiede vervaardig is, is voorts geïsoleer en identifiseer. Groeistudies is onder verskillende omgewingstoestande uitgevoer om die groeipatrone en eienskappe van die drie dominante giste nl. Kluyveromyces marxianus, Debaryomyces hansenii en Torulaspora delbrueckii te bepaal. 'n Kommersiële melksuurbakterie-kultuur (MSB) is in verskillende kombinasies met die giste gebruik in die groei- en fermentasie studies. Groei by verskillende pH waardes dui daarop dat dié giste, (veral T. delbrueckii), 'n metabolies-aktiewe rol speel gedurende en tot aan die einde van die melksuurfermentasie van die melk. T. delbrueckii het ook die beste groei getoon by 15°C maar was, inteenstelling met Kluyv. marxianus en D. hansenii, ni, ARC-Animal Nutrition and Animal Products Institute

English: The aim of the first part of the study was to investigate the ecological niche of mucoralean fungi in arid soil, with specific reference to the position these fungi occupy in the biogeochemical cycle of nitrogen. Consequently, selected mucoralean taxa occurring frequently in soil habitats, including strains from culture collections, as well as isolates obtained from a soil sample from arid Upper Nama Karoo, were used to evaluate in vitro growth to determine nitrogen sources and aw tolerances. Nine mucoralean fungal genera including 18 species were examined for the ability to utilise a series of nitrogen containing compounds and to grow at an aw of 0.955 on solid media. The nitrogen concentration in the media was 0.1 g.r1 and the series of nitrogen containing compounds were ammonium chloride, asparagine, sodium glutamate, sodium nitrite and potassium nitrate. The genera were Actinomucor Schostak., Backusella Hesselt. & J.J. Ellis, Cunningha'fnella Matr., GongronelIa Ribaldi, MortierelIa Coem., Mucor Fresen., Rhizomucor Lucet & Costantin., Rhizopus Ehrenb. and Thamnostylum Arx & H. P. Upadhyay. Thirty-nine fungal strains obtained from culture collections (CBS, MUFS and PPRI), as well as 12 soil isolates from the Karoo, were tested. All the species and strains tested in this study were able to utilise asparagine and glutamate. Strains belonging to CunninghamelIa, Mucor racemosus Fresen., Rhizopus microsporus Tiegh. and Rhizopus stolonifer (Ehrenb.: Fr.) VuilI. were unable to utilise ammonium chloride. Strains of CunninghamelIa, MortierelIa, Rhizomucor, Rhizopus microsporus and Rhizopus stolonifer were unable to grow on nitrate as sole nitrogen source. Nitrite was found to be toxic to species belonging to CunninghamelIa, MortierelIa, Rhizomucor, Rhizopus and Thamnostylum. Members of GongronelIa, MortierelIa, Mucor racemosus, Rhizomucor and Thamnostylum were unable to grow at an a, of 0.955. The aim of the second part of the study was firstly to get an indicatio, Afrikaans: Afrikaans: Die doel van die eerste gedeelte van hierdie studie was om die ekologiese nis van mucoraliese fungi in droë grond te bestudeer, met spesifieke verwysing na die posisie van hierdie fungi in die biogeochemiese siklus van stikstof. Uitgesoekte mucoraliese taksa wat gereeld in grondhabitatte voorkom, insluitend stamme vanuit kultuurversamelings en isolate verkry uit Ongrondmonster van die droë Boonste Nama-Karoo, is gevolglik gebruik om in vitro groei vas te stel, ten einde stikstofbronne en aw toleransies te bepaal. Nege mucoraliese fungusgenera, wat 18 species insluit, is ondersoek vir hul vermoë om ‘n reeks stikstofbevattende verbindings te benut en by ‘n aw van 0.955 op soliede media te groei. Die stikstofkonsentrasie in die media was 0.1 g.l-1 en die reeks stikstofbevattende verbindings was ammoniumchloried, asparagien, natriumglutamaat, natriumnitriet en kaliumnitraat. Die genera was Actinomucor Schostak., Backusella Hesselt. & J.J. Ellis, CunninghamelIa Matr., GongronelIa Ribaldi, MortierelIa Coem., Mucor Fresen., Rhizomucor Lucet & Costantin., Rhizopus Ehrenb. en Thamnostylum Arx & H. P. Upadhyay. Nege-en-dertig fungusstamme wat uit kultuurversamelings (CBS, MUFS and PPRI) verkry is, asook 12 grondisolate uit die Karoo, is getoets. AI die species en stamme wat in hierdie studie getoets is, kon asparagien en glutamaat benut. Stamme wat tot CunninghamelIa, Mucor racemosus Fresen., Rhizopus microsporus Tiegh. en Rhizopus stolonifer (Ehrenb.: Fr.) Vuill. behoort het, was nie in staat om ammoniumchloried te benut nie. Stamme van CunninghamelIa, MortierelIa, Rhizomucor, Rhizopus microsporus en Rhizopus stolonifer kon nie op nitraat as enigste stikstofbron groei nie. Nitriet is gevind om toksies te wees vir species wat behoort tot CunninghamelIa, MortierelIa, Rhizomucor, Rhizopus en Thamnostylum. Lede van GongronelIa, MortierelIa, Mucor racemosus, Rhizomucor en Thamnostylum kon nie by Ona, van 0.955 groei nie. Die doel van die tweede deel van die, National Research Foundation (NRF)

English: Cheese processed by traditional or modern methods inevitably produces large quantities of whey (approximately 84% of the volume of milk used). The disposal of whey is becoming a major industrial and environmental health problem and is difficult to separate from cheese technology. However, since a greater appreciation of the inherent nutritional value of whey constituents for both humans and livestock has become apparent, various new research projects have been initiated. In the light of growing global food shortages, the most logical use of whey would be to return it, in a palatable form, to the human food chain. The high salt content, low energy ratio and sweetening power of lactose, however, place constraints in the way of developing whey-derived food products. Single-cell protein, using deproteinized whey offer attractive new possibilities, not only from the standpoint of the current exhaustion of protein sources, but also because such food products have great potential for acceptance. The use of deproteinized whey offers attractive financial opportunities for the dairy industry by providing good quality whey protein on the one hand and by further processing of the deproteinized whey on the other. This can lead to even greater economic advantages if the deproteinized whey is enriched by means of suitable yeast strains to enhance the single-cell protein content. This protein enriched whey can primarily be applied for stockfeed with the envisaged development of a whey based food product for human consumption later. Fourteen lactose utilizing yeast strains, capable of fermenting lactose and producing high protein contents when grown on whey, were isolated from whey and its immediate environment. Priority selection studies were performed by growing each strain on whey, obtained during the processing of Cheddar cheeses, while monitoring their fermentative abilities, protein production capacity and the depletion of lactose. Based on these results, a yeast spec, Afrikaans: Kaas geprosesseer deur tradisionele en moderne metodes produseer 'n groot hoeveelheid wei, nagenoeg 84% van die volume van melk gebruik tydens kaasprosessering. Die storting van wei verskaf tans besoedelings probleme van groot omvang. Bewuswording van die voedingswaarde van wei vir beide menslike en dierlike gebruik het gelei tot talle nuwe navorsingprojekte. In die lig van die huidige voedseltekorte veral proteïen, bied die omskakeling van wei na bruikbare produkte soos enkelselproteïen-produkte 'n baie goeie alternatief. Die hoë soutkonsentrasie, lae energieverhouding en lae soetheid van laktose, plaas 'n demper op die ontwikkeling van nuwe weiprodukte. Die gebruik van gedeproteïeniseerde weipermeaat verskaf goeie finansiële vooruitsigte aan die suiwelbedryf deur die verskaffing van hoë kwaliteit weiproteïen aan die een kant en die benutting van gedeproteïeniseerde wei of permeaat aan die ander kant. Dit kan lei tot nog groter ekonomiese voordele indien 'n geskikte gisstam gevind kan word om sodoende die proteïen inhoud daarvan te verhoog. Hierdie proteïen verrykte weipermeaat kan aangewend word as veevoer met die oog op die ontwikkeling van 'n voedselproduk vir menslike gebruik in die toekoms. Veertien verskillende laktose benuttende gisstamme, wat in staat is om proteïen te produseer vanaf wei, is geisoleer vanaf 'n kaasfabriek en -fabrieksomgewing. 'n Seleksieprosedure is uitgevoer waartydens elke stam in gepasteuriseerde wei verkry tydens Cheddar kaasvervaardiging, geinokuleer is en hul fermenterende eienskappe asook proteïen produksie en uitputting van laktose gemonitor is. Gebaseer op hierdie resultate is 'n gisspesie naamlik Kluyveromyces marxianus var. lactis geselekteer vir verdere fermentasie studies. Hierdie gisspesie is gebruik om 'n gefermenteerde weiproduk met 'n hoë enkelselproteïen konsentrasie te produseer. 'n Hoë konsentrasie van proteïen naamlik 1.18 mg/ml is verkry tydens 'n fermentasieperiode van 22 uur sonder enige byvoegings tot p