Masters Degrees (Food Science)

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    The quest for safe irrigation water: investigating uv irradiation treatment of river water to reduce microbial loads
    (Stellenbosch : Stellenbosch University, 2022-04) Oosthuizen, Marco; Sigge, G. O.; Lamprecht, C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    ENGLISH ABSTRACT: Several studies have investigated the microbiological and physico-chemical characteristics of some Western Cape rivers used as sources of irrigation water for fresh produce. During this study, four Western Cape rivers were studied. The findings have shown that some of the rivers may pose a public health risk for consumers and jeopardise fresh produce safety, as tests indicated that Escherichia coli (E. coli) counts often exceeded the recommended irrigation water guidelines. As a water disinfection treatment, ultraviolet (UV) irradiation has proven to be effective and environmentally friendly, however, the application is still relatively novel in South Africa. Therefore, the aim of this study was to investigate UV irradiation treatment of river water to reduce microbial loads, for improved fresh produce safety. In the first research chapter (chapter 3), the variation in microbial and physico-chemical characteristics of a Western Cape river system over a longer distance (including sites that were after confluence points with other rivers) was investigated. The results showed that the water quality of one river system varies at different sampling sites, often exceeding guideline limits. Ultraviolet transmission (UVT %) and E. coli counts ranged from 28.00 to 90.40% and 2.322 to 3.913 log CFU.mL ̄¹, respectively. Several point and non-point pollution sources along the river could have resulted in the variations observed. Shiga toxin-producing Escherichia coli (STEC) and Extended spectrum beta- lactamase (ESBL) – producing Enterobacteriaceae were detected at certain water sites. These results suggested that, left untreated, water from this river could affect fresh produce safety as a result of microbial transfer that can occur during irrigation. The second research chapter investigated the effect of low-pressure, lab-scale UV doses (20, 40 and 60 ̄²) on the Heterotrophic Plate count (HPC) and Total Psychrotrophic Aerobic Bacteria Count (TPAC) populations. Results indicated that these populations showed UV resistance, and certain pathogens such as Bacillus cereus and Aeromonas hydrophila were identified from the surviving populations. It was also observed that UV irradiation eliminated most STEC and ESBL-producing strains, which is an important observation considering the advantages UV disinfection can have for fresh produce safety. In the third research chapter larger volumes of river water (1 000L) were treated in a medium- pressure UV disinfection pilot plant. Four different bag filters (5, 20, 50 & 100 μm) were evaluated as a pre-treatment step prior to UV disinfection, with the purpose of improving the water quality. Results showed slight improvements in suspended solids, with minimal reductions in dissolved and microbial content. However, bag filters with the smallest pore size of 5 μm showed best results. Medium-pressure UV treatment at pilot-scale was tested on large volumes (1 000 L) of water from three rivers. Results showed that the efficacy of the UV system is highly dependent on the water quality of the river. A single 20⁻² UV dose was applied, followed by a second UV dose of 20⁻² for each of the three rivers. The results indicated that E. coli, coliforms, STEC and ESBL- producing Enterobacteriaceae were inactivated with some HPC colonies showing UV resistance. In addition, other important pathogens such as Listeria monocytogenes that was detected in some the rivers, did not survive the lowest UV dose of 20 ̄². Overall, it was established in this study that the water quality varies in river systems, where untreated river water often exceeded irrigation water limits. The efficacy of both the low-pressure laboratory-scale, and medium-pressure pilot-scale UV systems are highly dependent on the initial physicochemical water quality of the river treated. The UV dose response of microorganisms differed, as some survived the UV radiation applied, which should be monitored for pathogenic bacteria. However, with proper pre-treatment and UV dose optimisation, UV irradiation can effectively reduce pathogenic microbial loads to acceptable levels. This method shows potential for upscaling to on- farm UV disinfection of irrigation water.
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    Modelling the environmental, social, and economic implications of using fruit pomace as an alternative livestock feed resource: a system dynamic modelling approach
    (Stellenbosch : Stellenbosch University, 2022-04) Bakasa, Clinton; Mudavanhu, Shepherd; Sigge, G. O.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    ENGLISH ABSTRACT: This study assessed the joint dynamic environmental, social and economic implications of utilising wine grape pomace as an alternative livestock feed in South Africa. The specific study objectives were met using a systematic approach that was done through a 3-pronged research process consisting of a detailed literature review, a qualitative analysis and individual synthesis of information and the construction of a qualitative system dynamic model in the form of a causal loop diagram. This was done using the Vensim PLP software, in order to explicitly show the complexity, interactions between the modelled systems variables and the corresponding feedback loop relationships. The study results showed that the estimated amount of grape pomace produced ranged between 248 720 and 304 941 tons per annum. This shows that if wine grape pomace was to be exploited as an alternative livestock feed through incorporating it into commercial feed, there is a significant amount of it to serve as a feedstock for commercial livestock feed formulations. The research study also showed that the benefits of using wine grape pomace as a livestock feed in cattle and sheep by far outweigh the shortcomings posed by this type of fruit pomace. Lastly, the complexity associated with producing and using wine grape pomace as an alternative livestock feed was explicitly illustrated (in the form of a causal loop diagram), explained and discussed. The qualitative model developed explicitly illustrated the inter-relationships between the joint dynamic environmental, social and economic implications of producing and using wine grape pomace as an alternative livestock feed in South Africa. The insights coming out from this study could potentially assist decision makers in the future to come up proactive policies and initiatives that are tailored to encourage the commercial utilization of this waste by-product as a feedstock for commercial livestock feed.
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    An assessment of the potential contribution of micronutrient-enriched food products available from major food retailers to the micronutrient intake of South African adolescents
    (Stellenbosch : Stellenbosch University, 2022-04) Barkhuysen, Janine; Sigge, G. O.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    ENGLISH ABSTRACT: Recent global actions have brought attention to health and nutrition issues facing adolescents and the need to address adolescent malnutrition in all its forms. Malnutrition may include under- or overnutrition, and micronutrient deficiencies or excesses. Micronutrient fortification and enrichment of food products can assist in the prevention of micronutrient deficiencies. However, to protect against other forms of malnutrition, the healthfulness or nutritional quality of these food products should also be considered. Micronutrient-enriched food products are available in South Africa. However, limited information is available on the extent of micronutrient-enrichment and the potential of these food products to contribute to adolescent intake of micronutrients without adding to the burden of overnutrition and the risk of multiple non-communicable diseases (NCDs) later in life. This research assignment aims to add to the knowledge base in this area by assessing the potential contribution of micronutrient-enriched food products available in South Africa to the diet of adolescents. A cross-sectional study of the South African micronutrient-enriched packaged food and beverage supply during a three-month period (July to September) in 2021, was used to assess the potential contribution of these food products to the diet of adolescents in terms of micronutrient content and healthfulness. Primary data (involving ingredient lists and nutritional information) was collected online from the main food retailers in South Africa. The micronutrient-enriched food products were tabulated and categorised according to the Nutrient Profile Model for the World Health Organization African Region. A total of 422 food products were found to be enriched with vitamins and/or minerals. The beverage category had the most micronutrient-enriched food products in this study (46%), followed by the breakfast cereals category (24%). Vitamins were most frequently added, led by vitamin A (55% of micronutrient- enriched food products). Minerals were added less frequently, with iron being the most frequently added mineral (26% of micronutrient-enriched food products). The breakfast cereals category had the greatest range of enrichment, with some food products enriched with 13 vitamins (A, B1, B2, B3, B5, B6, B7, B9, B12, C, D, E and K) and eight minerals (calcium, chromium, iron, iodine, magnesium, phosphorus, selenium, and zinc). Micronutrient-enrichment levels varied between the food products, but most of the levels were high enough for South African nutrient content label claims. This indicates that the micronutrient-enriched food products in this study could potentially contribute towards the daily intake of micronutrients by adolescents. However, only 9.5% of the micronutrient-enriched food products are suitable for inclusion in a healthy diet for adolescents, as the rest may contribute towards the burden of overweight and diet-related NCDs. This presents a valuable opportunity to the South African food industry for product reformulation to contribute to the health and nutrition of adolescents.
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    Incorporating agricultural by-products as functional ingredients in the food industry to improve the nutritional properties of food items and investigating consumer perceptions regarding acceptability.
    (Stellenbosch : Stellenbosch University, 2022-04) Pillay, Kalle Veronica; Sigge, G. O.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    ENGLISH ABSTRACT: Numerous studies have highlighted the negative impact agricultural and food waste contribute to the environment and have pursued alternative approaches to facilitate eco-friendly practices to promote sustainability. The brewery industry is considered a large contributor to environmental waste and many studies have highlighted the nutritional potential of reutilizing brewery by-products such as brewer’s spent grain (BSG) which frequently enter waste streams. Breweries ought to seek opportunities to foster sustainable practices which have the potential to reduce operational costs. A descriptive research study was carried out to investigate the potential of upcycling BSG. Participants were recruited to participate in the study through a combination of non-probability sampling techniques, purposive and snowball sampling utilizing an online survey questionnaire to gather information on brewery operations amongst 10 purposively selected breweries within KwaZulu- Natal, South Africa. Breweries and consumers have a role to play in ensuring environmental sustainability therefore consumer perceptions regarding waste reduction practices and repurposing agricultural by-products were investigated. Adults between the ages of 18 - 50 years who self- identified as health-conscious were recruited to participate in the study. The aim of the study was to quantify waste, in the form of BSG within the brewing industry and investigate the perceptions amongst consumers in regard to incorporating their agricultural by-products as functional ingredients in the modern-day diet to promote a circular economy. The circular economy approach builds resilient economies and through managing our limited natural resources it minimises environmental degradation and provides societal benefits. The objectives for the study included i) Determining the quantity of BSG produced by breweries within KwaZulu-Natal ii) Determining the current practices for disposal of BSG amongst these breweries iii) Determining the perceptions amongst the general population regarding repurposing food waste and whether health considerations influence food consumption decisions. The data was analysed using descriptive and inferential statistics. The findings from the study revealed the predominant by-product in beer manufacturing was BSG and 90% of the breweries disposed their BSG as animal feed. Eighty percent of the breweries had shown interest in perusing upcycling methodologies. Significant results were obtained in relation to gender and high-fibre food purchases with more females 73% purchasing high-fibre foods in comparison to males. Age, food price, monthly income and high-fibre food purchase decisions had also revealed significant results p < 0.05. The varying income levels amongst study participants had a significant influence on food choice decisions and barriers to adopting healthier food choices such as those high in fibre. Results revealed consumers within the lower income bracket were more attentive to the price of food and 94% of consumers were in support of purchasing upcycled food products to reduce the environmental impact. The results reinforce the idea that innovative nutritious functional food product development supported by upcycling brewery by-products should consider the varying income levels of consumers as these value-added product formulations have the potential to contribute to food security and environmental sustainability.
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    Changing childcare demands due to Covid-19 regulations: Impact on maternal employment and household food security, in South Africa
    (Stellenbosch : Stellenbosch University, 2022-04) Barlow, Vine; Boatemaa, Sandra; Sigge, G. O.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    ENGLISH ABSTRACT: Background: Women traditionally bear the brunt of unpaid care work, however, with the ever- increasing population and struggling economy, their role in the economy has become more significant. Despite more women entering the labour market, they are still responsible for the majority of unpaid care work. The Coronavirus disease of 2019 (COVID-19) pandemic has led to the restriction of childcare services and school closures around the world, the increased childcare demands have fallen disproportionately on women. Women play an integral role in household food security through their reproductive and productive responsibilities. Their reproductive responsibilities refer to their care and domestic duties such as sourcing, preparing and serving food and caring for children. Their productive responsibilities refer to their paid work in the community which has an effect on their household resources for food. Methods: This study investigated the association between the government responses of COVID-19 and childcare, maternal employment, and household food security in South Africa, during June 2020 using data from the National Income Dynamics Study – Coronavirus Rapid Mobile Survey (NIDS-CRAM) . The NIDS-CRAM is a nationally representative sample of the South African population, that focusses on the socio-economic effects of the pandemic. Descriptive and multivariate analyses were conducted with a sample of 1664 women who had at least a child (<18 years old) in their care during June 2020. Results: More than a third of the mothers did not work in June 2020 (68%). Forty three percent of the mothers had increased childcare demands which impacted their ability to work. About 1 in 2 households ran out of money to buy food (45%). Mothers who reported that they were unemployed, and childcare affected their ability to work had increased odds of running out of money to buy food in June 2020 (OR=1.60, p=0.000). Women who reported that government grants were their main source of income, had increased odds of running out of money for food (OR=1.57, p=0.001). The number of children in the household also increased the odds of the household running out of money for food (OR=1.10; p=0.030) Conclusion: Increased childcare demands limited women’s ability to work or search for work during the lockdown. We established that mothers whose work was affected by increased childcare demands were more likely to run out of money for food. Therefore, we can conclude that childcare demands impact household food security. The risk of household food security increased with the age and number of children in care. Women who reported that government grants were their main source of income have increased odds of running out of money for food. We can therefore conclude that social protection grants are insufficient to protect household food security. Recommendation: The gender policy framework should incorporate programmes directly targeted at men, as a pathway for gender mainstreaming. Education and training on the importance of sharing the burden of unpaid care work can affect change in traditional gender roles. Furthermore, we also recommend that food security be prioritised in social development policies and that more resources are put towards social protection.