Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 137-149). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 137-149). Also available on the Internet.

Submitted in fulfillment for the Degree of Master of Technology (Biotechnology) in the Department of Biotechnology and Food Technology, Durban University of Technology, Durban, 2009. / Information regarding the nutritional value of wild food plants in Africa and current information varies from source to source. Prior to commercialization of wild foods the nutritional, ethnobotanical, medical, chemical, anthropological and toxicity requires investigation. Plants from the Amaranthaceae family were chosen because the family is characterized by several species which are used by indigenous communities as a source of nutrition in different plants of the world. The focus of this study was to investigate the nutritional and biological activities of three plants from the Amaranthaceae family viz. Achyranthes aspera, Alternanthera sessilis and Guilleminea densa that are considered famine plants. This study aimed to determine the nutritional value (proximate, minerals and vitamins), biological activity, toxicity and potential of a tissue culture system for three species from the family Amaranthaceae. Nutritional analysis comprised of determining moisture, ash, protein, fat, carbohydrate, dietary fibre and energy. Mineral analysis of calcium, copper, iron, magnesium, manganese, phosphorus, sodium and zinc was performed by microwave digestion and then analyzed by ICP Spectrophotometry. Vitamin A, Vitamin B1, Vitamin B2, Vitamin B3 and Vitamin C were also analyzed. For biological and safety analyses aqueous and methanolic extracts were prepared. Anti-oxidative and anti-inflammatory properties of the extracts were tested; antimicrobial activity was tested by evaluating the bactericidal, fungal effect and minimum inhibitory concentration on selected bacteria and fungi using the agar disk diffusion method. Anti mosquito potential was determined by setting up repellency, larvacidal assay and insecticidal assay. The safety and toxicity analysis was carried out by measuring cytotoxicity, toxicity and mutagenicity. The potential of an in vitro tissue culture system of A. aspera, A. sessilis and G. densa was determined using micropropagation. A. aspera indicated significant amounts moisture, ash, dietary fibre, protein, vitamin B1, vitamin B2, magnesium and manganese. Plant extracts of A. aspera had antibacterial activity against the Gram negative bacteria Esherichia coli, Pseudomas aeroginosa and Salmonella typhi; Gram positive bacteria Staphylococcus epidermis and Staphylococcus aureus. The methanolic extract had antifungal activity against Sacchromyces cerevisiae and exhibited significant free radical scavenging activity as well as 85% repellency against Anopheles arabiensis. The aqueous extract stimulated the growth of the K562 (Chronic Myclogenous Leukaemia) cell line and the plant extracts showed no mutagenicity or toxicity. A. sessilis indicated significant levels of ash, dietary fibre, protein, energy, vitamin A, vitamin B1, vitamin B2, vitamin B3, iron, magnesium and manganese present. Plant extracts of A. sessilis had antibacterial activity against Gram negative bacteria P. aeroginosa and Gram positive bacteria S. epidermis. The plant also showed antifungal activity against the yeasts S. cerevisiae and Candida albicans. The methanolic plant extract showed excellent antioxidant activity. The aqueous plant extract stimulated the growth of the K562 cell line and the plant extracts possessed no mutagenicity or toxicity. This plant grew well in a tissue culture system where it was propagated from callus to a fully grown plant able to survive in environmental conditions. G. densa has ash and dietary fibre, vitamin B2, vitamin B3 and iron. The plant extracts had antibacterial activity against Gram negative bacteria E. coli, P. aeroginosa and Klebsiella. oxytoca; Gram positive bacteria Baccilus stereathermophilus and S. aureus. The plant also has antifungal activity against C. albicans and significant repellency activity against A. arabiensis where it showed 100% repellency. This plant was not found to be mutagenic or toxic. The results obtained from this study show promising potential for the plants to be exploited as famine food plants. The nutritional value, biological activity and ability to micropropagate A. aspera, A. sessilis and G. densa indicates a good potential for purposes of harnessing biotechnological products.

From a confit tomato and potato tumbleweed with buchu to a cured snoek terrine rolled in wilde kruie and Cape bobotie puff pastry with blatjang, chefs that mix indigenous plants and local cuisine with European inspiration and training have proved popular in Franschhoek’s restaurants. In this boland town, the particular constructions of heritage through food, not only showcases regional flavours, but gestures towards the search for an elusive place-based ‘South African’ cuisine that is seen to be rooted in the land. Harkening back to old culinary practices and drawing from their own heritages, Franschhoek’s chefs are foraging, butchering, gathering, growing, fermenting, pickling and cooking over open fires with renewed vigour as they attempt to ground their cuisine, and indeed, themselves, in the soil around them. This thesis considers how, through the culinary repertoire of chefs in Franschhoek, food is constructed as heritage. Within this I look at what heritages are considered desirable, how food’s sensory and symbolic properties are used to their full potential, and who is behind these constructions of culinary heritage. Following on from this, I explore postcolonial and post-apartheid anxieties of place and belonging, as well as desired and emergent identities that are expressed through this culinary heritage.

Cyclopia intermedia E. Mey is harvested from the wild to produce honeybush tea. The presence of a lignotuber and its slow growth seems to hinder the cultivation of this species and wild harvesting is likely to continue. Species distribution modelling indicated that C. intermedia has a climate envelope that spans from the Eastern Cape to the Western Cape along the Cape Fold mountains. This regional distribution is threatened under future climate change scenarios with a range loss and shift identified for climate conditions predicted for 2050. More specifically, its niche was identified as south-facing slopes with sandy to loamy sand soils and water holding capacity that is higher than the surrounding areas. Some keystone Fynbos species were found to share this niche: Leucadendron salignum, Leucospermum cuneiforme, Protea neriifolia, Protea repens, Elegia filacea and Rhodocoma fruticosa. Cyclopia intermedia grows throughout the summer with flowering buds developing in autumn. These enlarge during winter with the flowers opening in early spring. Pods develop in November and seed set occurs during December. Harvesting plants increases their fecundity with cut plants producing more than twice the number of pods and seeds compared to their non-harvested counterparts. This is because resprouting plants produce more flowering stems than uncut plants. Controlled harvesting or localised short-cycle burning could be considered as a management option to improve fecundity of declining Cyclopia intermedia populations in protected areas. C. intermedia harvesting could occur every third year and stem colour was identified as a measure of harvest maturity. Where at least 30 percent of the population has orange (RHS colour 163A) stems the population is suitable for harvesting.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xi, 114 leaves / Eighteen traditionally leafy vegetables consumed as food or medicinal compounds by a majority of people in the KwaZulu Natal province of South Africa were analysed for the presence of potentially harmful chemicals (antinutrients) and for their toxicity and mutagenicity. The purpose of the study was to determine whether leafy vegetables were safe for human consumption. Chemical analysis showed that none of the vegetables contained cyanogenic glycosides, however all the vegetables contained oxalic acid ranging from 24.1 mg/ml to 798.2 mg/ml with Solanum nigrum, Portulaca oleracea and Mormodica balsamina showing the highest concentrations. Most of the vegetables contained negligible amounts of phytic acid and saponins, except for Momordica balsamina (3.01 mg/ml and 1.83 mg/ml, respectively). Fourteen of the plants contained alkaloids with Portulaca oleracea having the highest content (1.53 g total alkaloids/5 g leaf material). Eight of the plants were found to inhibit trypsin activity. These chemical analyses were carried out in duplicate and the mean and standard deviation were used. The Ames test revealed that none of the leafy vegetables produced a mutagenic frequency above 1, except 10 000 µg/ml organic extract of Senna occidentalis (mutagenecity considered at mutagenic frequency above 2), thus none were considered mutagenic. All 18 organic extracts did not kill off more than 50% brine shrimp and were thus considered non-toxic. On the other hand the aqueous extracts of seven vegetables, namely, Physalis viscosa, Amaranthus dubius, Justicia flava, Bidens pilosa, Senna occidentalis, Chenopodium album and Ceratotheca triloba, killed more than 50% of the shrimp and are thus considered toxic above 100 µg/ml. The MTT assay carried out on the organic extracts indicated that 17 vegetables did not kill off more than 50% of HepG2 cells and were thus considered non-cytotoxic. The aqueous extracts of four vegetables, namely, Justicia flava, Asystasia gangetica, Momordica balsamin and Senna occidentalis, however killed more than 50% of the shrimp and were thus considered cytotoxic above 1 000 µg/ml. It may be concluded from the antinutrient analyses and the bioassays on the 18 vegetables that caution needs to be maintained with the consumption of certain leafy vegetables included in this study, especially Senna occidentalis.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2007 xi, 114 leaves / Eighteen traditionally leafy vegetables consumed as food or medicinal compounds by a majority of people in the KwaZulu Natal province of South Africa were analysed for the presence of potentially harmful chemicals (antinutrients) and for their toxicity and mutagenicity. The purpose of the study was to determine whether leafy vegetables were safe for human consumption. Chemical analysis showed that none of the vegetables contained cyanogenic glycosides, however all the vegetables contained oxalic acid ranging from 24.1 mg/ml to 798.2 mg/ml with Solanum nigrum, Portulaca oleracea and Mormodica balsamina showing the highest concentrations. Most of the vegetables contained negligible amounts of phytic acid and saponins, except for Momordica balsamina (3.01 mg/ml and 1.83 mg/ml, respectively). Fourteen of the plants contained alkaloids with Portulaca oleracea having the highest content (1.53 g total alkaloids/5 g leaf material). Eight of the plants were found to inhibit trypsin activity. These chemical analyses were carried out in duplicate and the mean and standard deviation were used. The Ames test revealed that none of the leafy vegetables produced a mutagenic frequency above 1, except 10 000 µg/ml organic extract of Senna occidentalis (mutagenecity considered at mutagenic frequency above 2), thus none were considered mutagenic. All 18 organic extracts did not kill off more than 50% brine shrimp and were thus considered non-toxic. On the other hand the aqueous extracts of seven vegetables, namely, Physalis viscosa, Amaranthus dubius, Justicia flava, Bidens pilosa, Senna occidentalis, Chenopodium album and Ceratotheca triloba, killed more than 50% of the shrimp and are thus considered toxic above 100 µg/ml. The MTT assay carried out on the organic extracts indicated that 17 vegetables did not kill off more than 50% of HepG2 cells and were thus considered non-cytotoxic. The aqueous extracts of four vegetables, namely, Justicia flava, Asystasia gangetica, Momordica balsamin and Senna occidentalis, however killed more than 50% of the shrimp and were thus considered cytotoxic above 1 000 µg/ml. It may be concluded from the antinutrient analyses and the bioassays on the 18 vegetables that caution needs to be maintained with the consumption of certain leafy vegetables included in this study, especially Senna occidentalis.

This work is a school-based case study conducted amongst learners of a rural High School and the immediate community in Whittlesea in the Eastern Cape where I teach. The research was conducted by using different research methods such as worksheets, questionnaires, interviews, practical activities and observations as well as photographs to investigate three indigenous wild local vegetable food plants (imifino). The fundamental assumption of the research is that, imifino can be looked after and cared for, to become valuable vegetable food plants which can be used as supplements to the cultivated vegetable food plants (umfuno). The question was: How could this concept be brought into the curriculum? It had also been assumed that bringing knowledge of imifino into curriculwn contexts could be of benefit to South African learners. The study produced a variety of findings: • There is a general feeling that those who eat imifino are the poor. • There is a lack of interest among women interviewed in the preparation process, for example going to pick the food plants from the fields, washing them and preparing the leaves as food. • AmaXhosa males look upon eating imifino with contempt. • Some males among the younger generation are beginning to overlook tradition and are eating imifino. • Inclusion of indigenous agricultural knowledge in the curriculum was supported by learners and community members. Learners have interest in knowing about indigenous food plants. • Learners feel as Africans that they must learn about the indigenous food plants in school in order not to lose knowledge of these plants completely. • The study also identified that interpretation of learning outcomes with an indigenous knowledge focus, requires careful attention to socio-cultural factors, and not just technical/ practical factors. Previous knowledge of learners and community members about imifino was mobilized to develop a sample OBE learning programme unit (LPU /Lesson plan) for the Grade 10 FET of Agricultural Science curriculum. The case study illustrates that Learning outcome 3 of the Agricultural Science subject can be achieved if educators involve learners and community members in developing learning programmes.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy